W2A021K
<#/><I> <h> Examples of indigenous health practices: </h>
<#/><h> Positive aspects </h>
<#/>Indigenous health practices affect the way cosmopolitan medical services are perceived and used by indigenous people. <#/>For those conditions which have been shown to be amenable to indigenous treatment, cosmopolitan medicine may not be readily used. <#/>For conditions which are seen to be better treated using cosmopolitan methods, for example those requiring surgery with anaesthesia, indigenous practices are readily discarded. <#/>The most common situation, however, is that which requires the utilization of both indigenous and cosmopolitan services in a complementary fashion. <#/>Various indigenous health practices, both curative and preventive, will be discussed with a view to showing that some may be useful, others harmful and still others neither useful nor harmful. <#/>Understanding this distinction is critical in the attempt to utilize indigenous resources in health development. <#/>In this chapter, useful indigenous practices are discussed while in the next some negative practices are considered. <#/>
<#/><h> Curative services </h>
<#/>Through trial and error, indigenous communities discover and adopt practices which are efficacious in the management of different illnesses. <#/>Examples of such practices existing among Abagusii and Marakwet are presented here.
<#/>Herbal therapies of various kinds are effective in the management of indigestion problems, worms and cuts in both communities. <#/>The exact efficacy of the herbs is difficult to assess since some of it may be due to the placebo effect. <#/>Marakwet use herbal mixtures to prevent cuts and wounds from becoming septic. <#/>The herbs seem to work very well. <#/>There are, however, several serious problems pertaining to dosage, preservation and poisoning in the use of herbs. <#/>These issues are not dealt with effectively in indigenous medicine because of the few technological options available.
<#/>Child delivery with the assistance of TBAs is another positive practice common among both the Abagusii and Marakwet. <#/>Even where the delivery itself occurs in a hospital setting, the mother receives the bulk of her prenatal and postpartum care from TBAs. <#/>TBAs have a very good understanding of the birth process and, where they have received appropriate retraining, are able to refer clients with problems to the relevant specialists. <#/>The TBAs provide the psychological support and counselling which are not always available in cosmopolitan health facilities. <#/>Retrained TBAs can identify anaemia and other complications and provide relevant advice. <#/>The TBAs, however, still face a number of problems such as the lack of basic instruments with which to monitor the mother's blood pressure and foetal condition. <#/>There is also the common problem of infection developing from the use of contaminated materials and instruments.
<#/>Psychological support is a useful element in indigenous health practice, especially in the management of chronic conditions.
<#/>The Marakwet carry out a number of psychosocial procedures aimed at enhancing individual or community health or preventing illness. <#/>Some are also aimed at treating existing illnesses. <#/>Such practice is based on their broad conceptualization of health and the causation of illness. <#/>A number of rituals, <ea/>ayebisio (pl.), are performed to achieve one or more of the three purposes mentioned earlier—reinforcement, prevention and treatment.
<#/>The commonest <ea/>ayeba is that performed when it is thought that the patient or his family are in some way responsible for an illness, for example, through theft, abusing others or quarrelling. <#/>The <ea/>ayeba performed in such a case involves a prayer for the family conducted by elders. <#/>After prayers to <ea/>Asis, the elders bless the sick person by covering him with green leaves, a symbol of life for Marakwet. <#/>The ceremony is cathartic.
<#/>Other <ea/>ayebisio are performed to enhance health in general. <#/>This happens when an individual thinks that because of past behaviour he is not liked by other community members. <#/>The condition of unpopularity is believed to exacerbate even minor ailments so the appropriate <ea/>ayeba has to be performed.
<#/>Another type of psychosocial procedure carried out by Marekwet is called <ea/>lyopso. <#/><ea/>Lyopso is a cleansing ceremony aimed at preventing interpersonal and ritual forces from affecting an individual's health. 
<#/>Among Marakwet, ritual impurity is believed to be brought about by types of homicide or a ritual oath, <ea/>muma. <#/>If a person has committed homicide or sworn a ritual oath falsely, he needs <ea/>lyopso to cleanse his impurity.
<#/>Among Abagusii, various rituals and ceremonies are performed to heal patients whose illnesses are thought to involve interpersonal and/or spiritual forces. <#/>The ritual that is most commonly performed among Abagusii is <ea/>ekeng'wanso, literally, sacrifice. <#/><ea/>Ekeng'wanso is performed both to cure and to prevent illness.
<#/>All these rituals are performed to relieve the people involved from fears and to restore the confidence and courage needed to face life's challenges. <#/>Such procedures have one major common feature—they are performed by and for the group, the community. <#/>This feature reveals the communal nature of illness as perceived in the African setting.
<#/>Traditionally, Abagusii believe that <ea/>ekeng'wanso is essential for good health to prevail and for the prevention of all sorts of calamities. <#/>The <ea/>ekeng'wanso is offered to Engoro, creator, and <ea/>chisokoro, ancestors. <#/>Basically, <ea/>ekeng'wanso involves the killing of an animal of prescribed colour, age and sex. <#/>The meat is consumed by kin members and sometimes close friends are invited. <#/>The performance of <ea/>ekeng'wanso does not usually require the presence of a specialist. <#/>Any adult household head can lead the performance of <ea/>ekeng'wanso. <#/>The ceremony provides the occasion where past quarrels, unpaid debts, dishonoured oaths and other interpersonal problems are discussed. <#/>The ceremony is aimed at healing existing illnesses and preventing others from occurring. <#/>Treatment with materia medica precedes <ea/>ekeng'wanso and continues after it where necessary.
<#/><ea/>Ogoosia is another ceremony performed by Abagusii in their health seeking process. <#/><ea/>Ogoosia means literally "to cool down". <#/>The ceremony is performed when it is suspected that somebody with malicious intent is afflicting a family member by exacerbating what would otherwise be a simple illness. <#/>The ceremony involves the killing of a sheep and the use of leaves and flowers to bless the afflicted person. <#/>Kin and neighbours attend and appropriate songs are sung. <#/>An appeal is made anonymously but publicly to the individual who may be causing the affliction to stop his malice.
<#/><ea/>Ogokorerana is a ceremony performed when several misfortunes including, but not restricted to, illness, strike a family and it proves difficult to apportion responsibility. <#/><ea/>Ogokorerana is prescribed by a diviner and he may be present to direct the performance. <#/>The ceremony takes various forms and involves the eating of a meal in which family members and neighbours participate. <#/><ea/>Ogokorerana is a prayer to the ancestors to protect the family from misfortune and illnesses in particular.
<#/>Among families which no longer believe in the efficacy of traditional rituals and ceremonies, Christian fellowships and prayers replace the traditional forms. <#/>The multi-faceted causation of illness, requiring multi-dimensional therapy, is fully understood and accepted. <#/>In a number of instances, there is a quasi-Christian performance with traditional trappings. <#/>This is true especially among Abagusii, many of whom profess one or another form of Christianity.
<#/>In Africa illness is never merely a physical phenomenon. <#/>Social and spiritual factors are seen to be involved in some, especially chronic, illnesses. <#/>For the individuals and families concerned, the social and spiritual factors need to be dealt with before complete healing is achieved. <#/>Efficacy of treatment procedures, therefore, goes beyond the removal of physical symptoms and signs.
<#/><h> Preventive services </h>
<#/>Some scholars have erroneously portrayed non-western indigenous societies as lacking an understanding of both the concept and practice of prevention. <#/>This portrayal seems to be due to a superficial study of indigenous medical systems, even before these came into contact with western civilizations. <#/>Studies in several Kenyan communities have shown that traditionally all these societies believed that certain diseases could be prevented while others could not. <#/>Belief in the possibility of preventing illness led to a number of practices aimed at achieving this objective. <#/>These involved the use of both materia medica and appropriate ceremonies or rituals.
<#/>The Kikuyu, for example, believed a wide range of procedures and prohibitions to be essential for the prevention of illness. <#/>In cases where an individual was believed to be suffering from an infectious illness such as <ea/>ohere, scabies, or <ea/>ruhayo, severe cough, people avoided, or at least limited, close contact with the individual. <#/>If the head of a family suspected that family members, and especially children, were malnourished, he made attempts to procure the appropriate foods so as to prevent illnesses resulting from lack of adequate food. <#/>If an illness was associated with <ea/>Ngai, God, appropriate ceremonies were performed to treat a particular patient but just as importantly to prevent the illness from afflicting others. <#/>Charms and amulets were and are still worn by children and even adults to protect them from getting illnesses whose causation was thought to result from interpersonal problems, such as <ea/>kurogwo. <#/>(getting cursed). <#/>People who have been cursed perform the relevant ceremonies to prevent the negative effects of the curse.
<#/>The Pokot perform elaborate procedures in which both materia medica and ceremonies are believed to be important to prevent illness. <#/>Periodically the head of a family organizes the performance of the <ea/>ighat, a preventive ceremony. <#/>During <ea/>ighat, a set concoction of about ten herbs is prepared and a goat slaughtered. <#/>All family members drink the herbal mixture and plenty of soup prepared from the slaughtered goat. <#/>The aim of <ea/>ighat is to strengthen family members, both physically and spiritually, so that they can repel any attacks of illness. <#/><ea/>Ighat has existed among Pokot for as far back as they can remember.
<#/>Abagusii have several ways of preventing the physical, interpersonal and spiritual aspects of illness. <#/>Babies and young children are routinely given a mixture of herbs to prevent a wide range of illnesses. <#/>The herbs are administered orally with food or drink, applied as ointment or rubbed onto incisions made on the skin.
<#/>To prevent the interpersonal and spiritual aspects of illness, Abagusii use a process called <ea/>ogokireka omochie, "protecting the homestead". <#/>The process involves spraying the homestead with <ea/>amanyansi, some of which is then prepared as a drink and given to all family members to drink. <#/><ea/>Amanyansi is a herb believed to possess both medicinal and mystical powers of preventing illness. <#/>A sheep is also slaughtered and its stomach contents sprayed around the homestead.
<#/><ea/>Ogotakera is another procedure which Abagusii use to protect a baby from harmful interpersonal or spiritual agencies. <#/>If a baby is sickly and seems threatened by death, the mother and a group of elderly ladies take the baby to a cross-roads point, and lay him by the road side. <#/>Anybody passing through the place has to pray for the baby's good health and survival. <#/>The prayer and well wishes are accompanied with the presenting of gifts to the baby. <#/>The gifts may not have material value but are believed to show that the giver wholeheartedly wishes that the baby be protected by God from all kinds of illness. <#/><eaf>Ogotakera is completed by a prayer said at sunrise by the baby's mother. <#/>The mother holds the baby towards the rising sun and says "<ea/>Erioba onderere" which means "Sun (God), rear this baby for me". <#/>
<#/>Due to the spread of Christianity and western ideas, these procedures may not be acceptable to all members of a given community. <#/>Some members, because of Christianity or the wish to appear modern, may opt for Christian prayers and the laying on of hands in place of the indigenous practice. <#/>Even individuals who normally would not go to church may ask for prayers to be said for them to be healed.
<#/><h> Implications for health service delivery and development </h>
<#/>A number of positive health practices exist among Kenyan societies. <#/>Practices such as the use of herbal treatment, psychosocial support and indigenous child delivery need to be studied in detail with a view to encouraging those which are useful.
<#/>Concern for effective indigenous health practices will go a long way in facilitating more effective use of cosmopolitan medicine. <#/>Kenya's 1989-1993 Development Plan calls for more research to collect information on appropriate traditional diagnostic, therapeutic and rehabilitative technologies which could become part and parcel of formal health research and programmes 
</I>
W2A022K
<#/><I> <h>Clinical Aspects and Diagnosis of Hydatid Disease </h>
<#/>Section I
<#/><h> CLINICAL ASPECTS </h>
<#/>The clinical diagnosis of hydatid disease depends on a high index of suspicion. <#/>This is especially important in areas with sporadic cases. <#/>The classical case of advanced abdominal hydatid disease usually looks well despite having extreme distension of the abdomen . <#/>However, cysts appearing in rare sites such as in the orbit will often be missed. <#/>In the past enucleation of the eyeball was undertaken under the mistaken belief that it was due to neoplasm. <#/>Epilepsy may be the initial sign of intracranial hydatid cysts. <#/>A goitre with a cystic feel on palpation may be due to a hydatid cyst of the thyroid gland. <#/>The patient is usually euthyroid clinically. <#/>The vast majority of hydatid cysts are in the liver (about 70%) followed by the lung (20%). <#/>But Okelo has seen cysts in nearly every organ in the body.
<#/><h> Hepatic Cysts </h>
<#/>Following the ingestion of the eggs by man, the liver is the first filter from the portal circulation. <#/>The masses feel cystic with gross but painless abdominal distension. <#/>The masses feel cystic and are typically non-tender. <#/>Some large cysts may contain several litres of fluid. <#/>Irregular hepatomegaly is usually present. <#/>Both kidneys may be enlarged and hydronephrosis may occur. <#/>The case shown in Fig. 22 was seen in 1986 and the hydronephrosis resolved following albendazole therapy. <#/>Some of the patients seen were found to have several litres of hydatid cyst fluid.
<#/>In early 1986 a young Masai female was admitted with acute abdominal pain. <#/>She had two very large cysts, one of which had ruptured. <#/>This is an unusual case. <#/>Another interesting case was of an adult Turkana female who had obstructive jaundice.
<#/><h> Pulmonary Cysts </h>
<#/>These account for about 20% of all our cases. <#/>They are usually asymptomatic, although the authors have seen pulmonary cysts as cough and haemoptysis. <#/>Pulmonary cysts may co-exist with pulmonary tuberculosis. <#/>An adult male nurse who had fever, cough, crepitations and the sputum expectorated, showed plenty of protoscoleces. <#/>The classical pulmonary cyst is easy to diagnose radiologically. <#/>An interesting case was seen by Okelo in a child who had two large pulmonary cysts, one in each lung, both compressing the heart. <#/>The child preferred to rest in a head down position. <#/>Spontaneous rupture of a cyst during chemotherapy rarely occurs; but broncho-pulmonary distula may occur.
<#/><h> Bone Cysts </h>
<#/>These are rare. <#/>A young female, referred to Okelo, had a spontaneous pathological fracture of the right tibia . <#/>At operation, she was found to have multiple cysts at the fracture site. <#/>It healed on albendazole therapy. <#/>A young Turkana man was presented to French with a fracture below the left knee following a kick from a donkey. <#/>The fracture failed to unite and the unfortunate man had to have the leg amputated. <#/>This was before albendazole was available. <#/>In this case the tibia was also found to be full of cysts.
<#/><h> Orbital Cysts </h>
<#/>A high index of suspicion is necessary to avoid unwarranted and unjustified enucleation of the eyeball. <#/>In the past some of the eyeballs removed were discovered to be due to hydatid cysts, at histology. <#/>Orbit cysts often appear with proptosis which may be very gross. <#/>All the cases seen by Okelo have had gross papilloedema. <#/>The proptosis was unilateral in all of them. <#/>In one of the cases, the eyeball was right outside the orbit and when an operation was done the ectocyst was found to be very thick. <#/>It was excised and the eyeball replaced back into the orbit. <#/>She had been on chemotherapy with albendazole prior to surgery. <#/>The protoscoleces removed were all dead. <#/>Due to the long standing papilloedema the patient lost her sight from secondary optic atrophy. 
<#/><h> Cysts at Other Sites </h>
<#/>In the last nine years we have seen cysts in nearly all organs of the body including skin, heart, pericardium, kidney, ribs, ovaries, urinary bladder, brain, post-operative scars, gall bladder, spinal cord, thyroid gland and old scars.
<#/><h> DIAGNOSIS </h>
<#/><h> Immunodiagnosis </h>
<#/>Diagnosis of most cestode infections involves parasitological examination of biological samples like stool for the presence of the parasite. <#/>Infection of man with hydatidosis represents the larval stage of the worm. <#/>The nature of this infection precludes parasitological diagnosis of the disease. <#/>Thus hydatid disease is diagnosed through procedures which rely on the detection of an immune response directed at the parasite, E. granulosus.
<#/>Parasite derived components with capacity to induce an immune response include the egg (oncosphere), protoscoleces and secretory/ excretory products of the germinal membrane. <#/>Hydatid cyst fluid is enriched with the parasite antigens and is commonly used as the source of hydatid antigen. <#/>A person infected with hydatid is sensitized or primed to the antigens which pass through the cyst wall and subsequently enter the blood circulation. <#/>This leads to the induction of anti-echinococcus antibodies and primed T-lymphocytes. <#/>A number of immunological techniques have been developed based on the detection of hydatid antibodies. <#/>The major specific antibody detected is IgG and IgA while IgM, are present in low rates. <#/>IgE levels are usually raised. <#/>Although testing for antibody has been the practice, major emphasis is now focused on methods designed to detect circulating parasite antigens or parasite specific immune complexes. <#/>This offers better advantages of distinguishing active infection from past experience or recovered cases. 
<#/>In addition, monitoring the antigen is of tremendous value in evaluating a successful surgical operation and the efficacy of antihydatid chemotherapy. <#/>While the determination of T-cell function is an attractive diagnostic procedure, there are at present no reliable, reproducible or simple and rapid cell-mediated response tests for hydatid disease. <#/>Hence serological methods are the mainstay of hydatidosis diagnosis.
<#/>The most widely applied serological tests include:
passive haemagglutination (PHA)
immunoelectrophoresis, based on arc-5 band (IEP-5)
enzyme-linked immunosorbent assay (ELISA)
radioimmunoassay (RIA)
double diffusion (DD)
latex agglutination (LA) and
complement fixation test (CFT).
<#/>Of these, based on the experience of the authors in Turkana District, the choice of method in the Kenyan situation comprises of IEP-5, IHA (PHA) and DD. <#/>With the use of highly purified E. granulosus antigens, ELISA systems should increasingly complement or replace some of these tests particularly in detecting and measuring circulating antigens, non-specific and specific circulating immune complexes.
<#/><h> Double Diffusion (DD) </h>
<#/>This is one of the immunoprecipitation methods. <#/>Soluble antigen and antibody are allowed to combine in a solid support. <#/>Both diffuse towards each other and where the two meet, an immune complex is formed and precipitated if the proportions of antigen and antibody are optimal for cross-linking. <#/>The test is performed using purified agar such as Noble agar, iron agar and agarose in small petri dishes or on glass slides. <#/>Two wells are punched in the agar using DD template.
<#/>Hydatid cyst fluid antigen (HCF/Ag) is placed in one of the wells, while serum from a suspected E. granulosus infected patient is put in the other. <#/>Diffusion is allowed to occur in a moist chamber at room temperature. <#/>Between 24-48 hours later, precipitin arcs are formed if the serum contains anti-echinococcus antibodies.
<#/>The test is very simple to set up and reasonably cheap. <#/>Specificity to E. granulosus is enhanced by purification of hydatid antigens and both "arc-5" and "arc-4" precipitin bands can be demonstrated.
<#/><h> Immunoelectrophoresis (IEP-5) </h>
<#/>Immunoelectrophoresis based on "arc-5" precipitin band is a modification of the conventional electrophoresis and immunodiffusion test. <#/>The test is performed with agarose on glass slides. <#/>Complex hydatid antigens are placed in wells made with the aid of IEP template and separated according to their overall surface charge, and molecular sized by applying a <-/pontential> voltage difference across the slide. <#/>Antigenic components thus migrate depending on their physical and chemical properties. <#/>After separation of the hydatid antigens, serum containing suspected anti-echinococcus antibodies is introduced into the trough made in the agarose. <#/>Immuno-diffusion is allowed to proceed in a moist chamber for 24-48 hours or more. <#/>Reactivity against the hydatid antigens is demonstrated by the formation of a characteristic precipitation band designated "arc-5". <#/>This is due to reaction between antigen 5 (one of the key diagnostic hydatid antigens) and specific Echinococcus antibodies. <#/>The precipitin band has a well defined morphology that is associated with hydatid infections and to a less extent crossreactivity with cysticercosis and certain myeloma conditions. <#/>However, IEP-5 is considered the only reliable technique and provides a confirmatory test for E. granulosus infections.
<#/>A major drawback of the technique is a relatively high incidence of false negative reactivity. <#/>Work carried out by Chemtai and Okelo in Turkana District showed that IEP-5 test can only detect <-/upto> 60% of surgically confirmed hydatid patients. <#/>Several explanations have been given by the authors for this anomalous sensitivity reaction. <#/>As hydatid cysts among Turkana patients are enormous, it is conceivable that there is a continuous release of excess antigen into blood circulation. <#/>This leads to the formation of immune complexes and mopping up of anti-echinococcus antibodies leaving very low free antibodies in circulation. <#/>Alternatively, it is thought that infection with E. granulosus leads to profound specific and generalized immunosuppression. <#/>This parasite-induced immunodepression could lead to diminished antibody production due to perturbation in the immune-regulatory mechanisms. <#/>While it was not well demonstrated in the studies conducted in Turkana, false-negative results may also be associated with the site and viability of the cyst. <#/>Pulmonary cysts have been reported to show low immunoreactivity.
<#/>Finally, a general appraisal of serological tests reveals that conventional IEP has an inherent sensitivity of 5-10mg/dl which could also contribute to the poor performance of the test. <#/>Together, these factors account for the discrepancy of high incidence of sero-negative reactive hydatid patients detected using IEP-5 test.
<#/><h> Passive Haemagglutination Test (PHA) </h>
<#/>This represents one of the most sensitive agglutination-based serological tests. <#/>It is carried out using human or sheep red blood cells. <#/>The former are preferred as they are devoid of heterophile antibodies which interfere with the performance of the test. <#/>Cells can be preserved with formalin or pyruric aldehyde to prolong their use.
<#/>Hydatid antigen is coupled chemically to the red blood cells. <#/>The coating is effected through treatment of the cells with either tannic acid, chromium chloride or glutaraldehyde. <#/>Excess antigen is washed off and the sensitized red blood cells are reacted with hydatid patients serum sample. <#/>Cross-linking of the antigencoated red blood cells by the specific anti-echinococcus antibodies leads to agglutination or clumping together of the cells.
<#/>PHA is a highly sensitive test which detects more than 80% of surgically confirmed hydatid patients. <#/>This value is based on the experience of Chemtai and French with sera derived from Turkana district patients. <#/>However, specificity is dependent on the level of purity of the hydatid antigen. <#/>The use of the crude hydatid cyst fluid antigen gives false positive reactions against other taeniid worm infections, filariasis and fascioliasis.
<#/>The greatest application of PHA rests with its use in seroepidemiological studies. <#/>Sensitized red blood cells are lyophilised or freeze-dried and the test can be performed in the field without elaborate laboratory facilities.
<#/><h> Enzyme Linked Immunosorbent Assay (ELISA) </h>
<#/>This is an enzyme immunoassay which has increasingly been developed and applied in the immunodiagnosis of parasitic diseases. <#/>The system is adapted for detection of-specific antigen or antibody, specific and non-specific circulation immune complexes and rheumatoid like or anti-immunoglobulins. <#/>The test is performed in a variety of modifications. <#/>They all rely on the ability of either the antigen or antibody to adhere to plastic material e.g. polystyrene or polyvinyl chloride. <#/>After absorption of the protein, excess antigen is removed and the microtitre plates are incubated with enzyme-labelled antibody such as peroxidase-conjugated antihuman Ig (IgG, IgM or IgA). <#/>Excess conjugate is washed off and the plates are further incubated in the presence of an enzyme substrate. <#/>The product of the latter interaction develops as a colour that is visible or can be measured spectrophotometrically. <#/>The sensitivity and specificity of ELISA are high, but dependent on the purity of the antigen used.
<#/>The technique has been applied in the diagnosis of human hydatidosis and found to be particularly useful in the detection of circulating parasite specific antigens and immune complexes among free antibody false-negative reactive hydatid patients.
<#/></I>
W2A023K
<#/><I> <h> DRUG ABUSE AND DEPENDENCE (IN MEDICAL TERMS) </h>
<#/><h> PSYCHO-ACTIVE DRUGS </h>
<#/>Man has used and abused drugs since the beginning of civilization. <#/>During the last few decades of the twentieth century, there has been a marked increase in the use of psycho-active or mind-altering drugs.
<#/>Concurrent with the use of such drugs, however, has come their misuse. <#/>Virtually all drugs that produce dependence can cause:
- varying degrees of social and health problems
- economic problems
- subsequent poor national development.
<#/>The degree of harm produced in general depends on: 
- quantity of the drug consumed per occasion 
- frequency with which that quantity is consumed 
- duration of consumption (months or years) 
- methods of administration.
<#/>Other factors include age, sex, body size, personality and speed at which it is taken and whether it is used simultaneously with other drugs.
<#/>The harmful consequences of drugs and drug abuse can be short term (appearing rapidly after a single dose) or long term following repeated use over a long period. <#/>Dependence on drugs can be:
i) psychological
ii) physical
iii) both psychological and physical.
<#/>When dependence on a drug occurs it is characterised by: 
<#/>a. craving (obsessive - compulsive) for the drug, no matter which means is used to get it.
<#/>b. drug tolerance - that is need to increase the dose steadily to reach the desired effects.
<#/>c. withdrawal symptoms in case of abstinence (withdrawal syndrome or abstinence syndrome).
<#/>d. suffering ultimately caused to the drug addict or abuser and to the society as a whole.
<#/><h> SOURCES OF DRUGS </h>
<#/>Drugs are either obtained naturally or synthetic (man made).
<#/><h> Natural sources </h>
- animals 
- moulds and fungi 
- microbes.
<#/><h> Preparation </h<
<#/>Drugs are prepared and packed in several forms:
- powders
- tablets and capsules, lozenges (pills) 
- creams and lotions, ointments 
- liquids and solutions 
- pessaries and suppositories.
<#/><h> WAYS OF ADMINISTRATION </h>
<#/>Drugs enter the blood stream through several routes. <#/>The following are the major ones:
<#/>1. Oral or through the mouth: These drugs are ingested and take some time to act.
<#/>2. Injections through muscles or straight to the veins: The effect is felt in seconds or minutes after administration.
<#/>3. Topical: This route is simplest and safest. <#/>It is just applied on the skin or part of the skin needing treatment. <#/>They take longer to act (days or weeks).
<#/>4. Inhalation: Some drugs are inhaled through the respiratory tract and the effect is as sudden as that one of injecting through the vein. <#/>Such drugs are like volatile gases, cigarette smoke, chemicals, for example petrol and glue.
<#/>5. Rectally or vaginally: Suppositories are inserted rectally while pessaries are inserted through the vagina but these are rare cases.
<#/><h> EFFECTS OF DRUGS IN OUR BODIES </h>
<#/>When we take drugs, some physiological or pharmacological effects occur (immediate or acute effects). <#/>When a drug enters the blood stream, it reacts with our body cells. <#/>Either the cells are stimulated to act or they are blocked from acting. <#/>Their function is changed and this influences our feelings, emotions and behaviour.
<#/><h> USE OF DRUGS </h>
<#/>Drugs are important in our day to day life. <#/>They are either used as:
<#/>1. Stimulants or blockers for example when there is hyposecretion or underfunction
<#/>2. Antagonists or blockers for example pain killers
<#/>3. Replacement therapy for example iron, vitamins.
<#/>When drugs are used as medication the process is known as therapeutic. <#/>But when an individual uses a prescribed drug for purposes other than the one intended, it is known as drug misuse, for example using piriton tablets in higher dosage to induce sleep. <#/>When one uses drugs for non medical purposes persistently and for his own intended reasons, it is known as drug abuse. <#/>When this occurs beyond the will and control of the individual and is used persistently and excessively for non-medial purposes, then this condition is known as drug addiction or drug dependence.<#/><h> DRUGS COMMONLY ABUSED </h>
<#/>Drugs which are commonly abused by people are drugs of addiction. <#/>These are drugs which are habitually taken by individuals for non-medical purposes and with imminent craving. <#/>They are basically classified into five categories:
<#/><h> a. Sedatives </h>
<#/>These are drugs which reduce excitement or functional activities. <#/>They make one drowsy without actually inducing sleep. <#/>Examples are alcohol, barbiturates and peps.
<#/><h> Psychotropic Drugs </h>
<#/>The psychotropic drugs are generally defined to include the antipsychotics (major tranquillisers, neuroleptics), antidepressants, anxiolytics (minor tranquillisers) barbiturates and non-barbiturate hypnosedatives. <#/>It has now been widely recognised that the introduction of these drugs in clinical practice has played a major role in the positive revolution which has taken place all over the world in the last forty years in the care of the mentally ill. <#/>This revolution has been of enormous benefit to all mankind. <#/>Unfortunately the easy availability of these drugs has also led to widespread use, misuse and abuse, not only as a result of illicit use, but also as a result of legitimate medical use. <#/>It was in fact the recognition of these dangers which led to the drafting of the United Nations Convention on the psychotropics in 1971.
<#/>Of the psychotropic drugs, the antipsychotics, though widely used and frequently prescribed for a long period when used in treatment of schizophrenia, have little or no tendency to produce dependence and tolerance. <#/>Moreover, many of them do produce some nasty side effects even in small doses. <#/>For these reasons, the neuroleptics are currently not presenting significant problems of addiction. <#/>However, the minor tranquillisers and the barbiturate sedatives which have been used in the past or are currently widely used legitimately and illicitly have been shown to produce severe dependence, tolerance and serious withdrawal reactions. <#/>In small doses, both barbiturates and benzodiazepines relieve anxiety and tension resulting in calmness (tranquillity) and sleep. <#/>But in higher doses, barbiturates produce a state of drunkenness and a high feeling similar to the effects of alcohol. <#/>At these doses, toxicity occurs and this is characterised by slurring of the speech, staggering gait, sluggishness and impairment of memory. <#/>With prolonged use of high doses, barbiturates produce severe dependence, tolerance and cross tolerance with other cerebral depressants (alcohol, benzodiazepines). <#/>Unlike alcohol, the lethal dose of barbiturates does not increase as tolerance develops. <#/>The barbiturates addicts are therefore at great risk of sudden possible inadvertent overdose which may result in death. <#/>Barbiturates withdrawal syndromes which are initially characterised by anxiety, depression, insomnia, weakness and irritability may progress to confusion, delirium and convulsions. 
<#/>The benzodiazepines produce similar complications during dependence though slowly and less dangerously. <#/>But even at therapeutic doses, they may cause agitation and release of aggressive tendencies instead of tranquillity. <#/>Withdrawal symptoms are very similar to those of the barbiturates. <#/>Furthermore, because of the widespread use and easy availability of these drugs, they are frequently used in suicide attempts.
<#/>Certain related compounds such as glutethimide (Doriden) and Metha-qualone produce dependence syndromes and withdrawal reactions half way between barbiturates and benzodiazepines in terms of severity.
<#/><h> b. Stimulants </h>
<#/>These are the drugs which stimulate the C.N.S., altering many brain functions, for example, perception, reasoning and judgement, emotions and feelings, intelligence. <#/>Examples of these are amphetamines, cocaine and <ea/>miraa. 
<#/><h> (i) <afr/>Khat </h>
<#/>Most people living in the north, west and southern part of Africa, and indeed many other parts of the world, have probably not heard of the word <afr/>khat, and yet in eastern Africa and parts of the Arabian Peninsula, the word is as familiar as tea, cocoa, tobacco or beer. <#/>In these regions <afr/>khat has been used for many years because of its psychological effects, particularly among the Muslims who normally do not take alcohol for religious reasons. <#/><afr/>Khat (Catha edulis) or <ea/>miraa, <ea/>mairungi, as it is known in Kenya, is a tree of the family celestraceae which grows at high altitudes in East Africa and Yemen. <#/>It has fresh leaves and young shoots which when chewed produce a stimulating effect similar to amphetamines but milder. <#/>The active ingredients which have been isolated so far are cathine and cathinone.
<#/>Although traditionally it was mainly used by Muslim populations in these countries, its use has recently spread outside the traditional population to include young Non-Muslims who combine its use with alcohol or other drugs. <#/>When chewed, it produces mild or moderate
<#/>euphoria, suppresses appetite, sustains alertness, and abolishes sleep. <#/>It is therefore used as a means of relaxation, to facilitate communication during social events and to suppress sleep and fatigue in work situations which require sustained alertness and attention. <#/><afr/>Khat is among the three or four leading drugs of abuse in East Africa. <#/>It produces dependence, tolerance and mild withdrawal symptoms. <#/>Its use is associated with marked socio-economic problems such as family instability, economic strain, prolonged absence of the fathers from the family, malnutrition and poor educational performance in children, some of whom become frankly delinquent.
<#/>Established <afr/>khat addicts spend a considerable proportion of their salaries and time on the habit. <#/>The twenty four hour life cycle of the <afr/>khat addict consists of eight hours of searching for the drug, eight hours in chewing it and eight hours of sleep! Some of the medical problems that have been associated with frequent heavy use of <afr//>khat include tooth decay, gastritis, constipation and in men spermatorrhoea and impotence.
<#/><h> The Controversy on <afr/>khat use </h>
<#/>Currently, there is a lively debate going on in the <afr/>khat producing countries for and against khat chewing. <#/>That excessive <afr/>khat use is associated with significant health and social-economic problems is no longer in dispute especially among health personnel. <#/>What remains unclear is the amount that constitutes abuse and which leads to harm. <#/>In economic terms, the cultivation of <afr/>khat as a crop is without doubt a profitable business that has surpassed other cash crops such as coffee in some countries. <#/>In Kenya for instance, the export of <afr/>khat brings into the country the much needed foreign exchange earnings! In any case there has not been any major local study to date which has conclusively established the association of <afr/>khat use with health and socio-economic problems serious enough to warrant prohibition. <#/>There is an urgent need for such a study which may assist the governments to define the position of <afr/>khat cultivation and trade.
<#/><h> (ii) Psychostimulant Drugs (Cocaine and Amphetamines) </h>
<#/>The health consequences of the use and abuse of these drugs are similar. <#/>Taken in small doses they produce a sense of exhilaration (euphoria), increased alertness and reduction of fatigue and hunger. <#/>Larger doses intensify these feelings and may lead to bizarre, erratic behaviour, hostility and violence. <#/>These behavioural disturbances are accompanied by physical symptoms of over-stimulation of the sympathetic nervous system, such as accelerated heartbeat, raised blood pressure and temperature and fast breathing. <#/>Taken in even higher doses, as may occur in an overdose, acute toxic reactions will occur. <#/>These consist of <-_agitations><+_agitation>, restlessness, delirium, hallucinations and even delusions and in serious cases tremors, lack of muscle coordination, spasms and convulsions. <#/>Death may even result from respiratory arrest, cerebral haemorrhage and <-/hyperthermia>.
<#/>When used repeatedly over long periods, dependence (physical and psychological), tolerance and withdrawal symptoms will occur. <#/>Chronic use may also produce typical hallucinations, <-/formication> or cocaine bug (a sensation as of ants crawling over the body) and delusions of persecution. <#/>States of fluctuation between periods of induced elation and drug free periods of depression and apathy with suicidal ideas and behaviour are also common. <#/>Chronic amphetamine dependence is very frequently associated with weight loss, malnutrition, vitamin deficiencies and increased susceptibility to infections. <#/>Chronic cocaine snorting is associated with stuffiness and running nose and perforation of the nasal septum. <#/>Severe psychotic illness indistinguishable from paranoid schizophrenia occurs with heavy use of both drugs. <#/>Withdrawal symptoms, which are more severe in amphetamine than in cocaine dependence, initially consist of craving, fatigue, prolonged disturbed sleep, hunger followed by irritability, depression and suicidal behaviour. <#/>Intravenous cocaine use is further associated with increased risk of abscesses, hepatitis, septicaemia, AIDS and tetanus.
<#/><h> (iii) Cannabis (<afr/>bhang) </h>
<#/>Harmful consequences of cannabis use may result from the dependence syndrome, tolerance, withdrawal phenomena and possibly direct toxic effect. <#/>However the nature, frequency and severity of its harmful effects have been demonstrated mainly in animals. <#/>Evidence of serious damage caused to human health is also accumulating. <#/>Immediate consequences of cannabis use (observed within a few minutes after taking the drug) are feelings of being 'high', that is, mild to moderate euphoria, and some relaxation. <#/>At a higher dose, cannabis may cause distortion of time and other perceptions. <#/>Thus a time interval may appear prolonged, sound and colour perceptions may also be sharpened or distorted. <#/>At a still higher dose, cannabis may interfere with attention, concentration, memory and logical thinking, so that an individual's ability to perform complex actions or to make sound judgements becomes impaired. <#/>Such a person can therefore become violent and run into serious problems such as accidents if driving or operating a machine. <#/>At an even higher dose, a cannabis user may develop a psychosis characterised by restlessness, confusion, excitement, panic, paranoia and hallucinations. <#/>At the time of writing it is not known whether such psychosis is due directly to the toxic effect of the drug or to the unmasking of psychosis in a predisposed individual. <#/>Cannabis psychosis is a short-lived illness in the majority of people, but it constitutes between five and ten percent of acute cases admitted into mental hospitals in Africa. <#/>A small proportion of chronic heavy users of cannabis may develop the 'amotivational syndrome' which is characterised by slow, progressive loss of energy and drive, apathy, memory impairment, poverty of ideas and deterioration in personal hygiene. <#/>These complications can disappear after several months if drug use is discontinued. <#/>Other reported health consequences among heavy cannabis users are lung diseases, chromosome abnormality, carcinogenic effects, suppression of the immune system and interference with male reproductive functions. <#/>Recently clear evidence has linked heavy and chronic cannabis use with damage to the respiratory system, especially in the occurrence of bronchitis, inflammatory change, reduction in gas diffusion and lung cancer.
<#/>c. Hard drugs or narcotics 
<#/>These are very strong pain-killers and sleep-inducing drugs, for example heroin, opium, morphine, pethidine, which produce physical and psychological dependence. <#/>They are mostly injectables and are very dangerous. <#/>The sleep induced is unnatural.
<#/>Opiates (Heroin, opium, morphine, pethidine etc) 
<#/>Among these drugs, the one which is currently causing a lot of concern in Africa is heroin. <#/>Available information indicates that the use and abuse of heroin, which until recently was confined to only one or two African countries, seems to be spreading very fast. <#/>Newspaper reports of seizures of heroin in transit as well as arrests for possession have become frequent. <#/>The use and abuse of opiates is associated with some of the most serious health hazards. <#/>The immediate effect of these drugs is pain relief and induction of a pleasant, dreamy, detached euphoria. <#/>But restlessness, nausea and vomiting may also occur. <#/>With moderate and high doses the body feels warm and extremely heavy, with dry mouth, and the user may go into 'nod' - an alternating wakeful and drowsy state during which the world is forgotten. <#/>At a still higher dose, breathing becomes progressively shallower as the respiratory centres get depressed and drowsy. <#/>On physical examination at this stage there is contraction of the pupils (miosis), cold moist skin, intense constipation, and death may occur as a result of respiratory failure.
<#/>Other dangers of short term use of heroin in particular result from the mode of administration, which is mostly done illegally, and the composition of the dose is not well known, as the dealers tend to dilute it with other substances. <#/>Thus a fatal overdose or severe abstinence syndrome can occur. <#/>Furthermore the material used for 'cutting' may be active drugs such as strychnine, barbiturates, amphetamines or inactive substances such as talcum powder, or even household cleaners. <#/>The presence of large insoluble particles constitutes an additional danger if injected intravenously, by obstructing the small vessels in the eyes or brain. </I>
.
W2A024K
<#/><I> <h> CHAPTER ONE </h>
<#/><h> 1.10 INTRODUCTION </h>
<#/>Most diets in developing countries are deficient in protein. <#/>The total protein consumed in developing countries per person is 56 grams compared to 90 grams in economically developed countries. <#/>It has been recommended that for good health each person needs at least 70 grams of protein per day . <#/>Some of the relatively cheap food crops that can help alleviate this protein crisis are the grain legumes of which the common bean Phaseolus vulgaris L. <#/>has been reported to play a vital role in most developing countries .
<#/>The common bean is one of the main grain legumes grown in the tropics and is grown extensively in East Africa and Asia. <#/>Singh and Van Emeden (1979) estimated the world hectarage under beans as 2.4 million. <#/>As was noted above, beans as a source of protein can play an important role in the predominantly cereal diets in tropical countries such as Kenya because of their high food value (table 1). <#/>The protein content of beans has been reported to be in the range of 16 - 33 % depending on bean variety and environmental conditions under which they are grown .
<#/>Nutritionally beans are 2 - 3 times richer in protein content than cereal grains , and are therefore often incorporated into livestock feed; and this has improved livestock production and inland fish production . <#/>Furthermore, beans require little additional nitrogenous fertilizers for average growth because they have the capacity to provide their own nitrogenous compounds through bacterial nitrogen fixation in their root nodules. <#/>The bacteria convert nitrogen gas from the air into nitrogenous compounds which are utilized by beans for growth and development. <#/>In Kenya, the common bean is the major grain legume in terms of production and consumption . <#/>It provides the cheapest source of protein, being about four times cheaper than animal protein. <#/>It is cultivated in various parts of the country along with other crops (Table 2). <#/>Mostly it is intercropped with other crops especially maize.
<#/>However, there are a number of factors that limit production of beans which include plant diseases, unreliable rainfall, high temperatures, inadequate plant nutrients in the soil and above all, pests. <#/>Pests cause damage to the beans in the field as well as in the store. <#/>In the store, damage is caused by bruchids, of which the common bean bruchid Acanthoscelides obtectus Say causes considerable damage due to the feeding behaviour of their larvae. <#/>Once attacked by the bruchids the quantity and quality of the stored bean seeds are greatly reduced.
<#/>The extent of economic losses due to insect attacks on stored beans are known to be substantial in various countries. <#/>Thus, in Mexico and other Central American countries economic losses have been estimated as 35 per cent and in Brazil as 13 per cent . <#/>In Kenya, it has been reported that 50 - 75 per cent of bean farmers experience crop loss to insects despite using various insect control methods .
<#/>A. obtectus has been controlled using insecticides such as lindane, gamma B.H.C. <#/>and malathion. <#/>However, the control of stored product insects using malathion and lindane has been reported to have failed in several countries due to emergence of resistant strains . <#/>Insect pests resistant to common insecticides are rapidly increasing . <#/>Moreover, insecticide residues in stored products could be more hazardous than in field crops. <#/>This is because in the store, insecticides are not exposed to weathering processes which reduce the hazardous effects of insecticides in field crops.
<#/>Therefore, there is need to develop more effective and safe control measures for A. obtectus. <#/>One of these seem to be the breeding and selection of new varieties of beans that are resistant or less susceptible to attack by A. obtectus . <#/>However, little has been done about it. <#/>Plant resistance as a method for insect pest control offers many advantages. <#/>In some cases it is even the only method that is effective and practical . <#/>For crops grown in developing countries, perhaps the most attractive feature of using pest resistant varieties of crops including beans is that virtually no skill in pest control or cash investment is required at the grower level .
<#/>Furthermore, a major advantage of using resistant varieties is the induction of a constant level of suppression on pest population growth. <#/>The number of pests which attack resistant varieties usually decline over time making control with insecticides easier. <#/>Resistant varieties are also highly compatible with biological control since both methods usually do not greatly affect natural enemies of the pest species . <#/>Breeding and selection of plant varieties resistant or less susceptible to insect attack is based on insect-host plant relationships. <#/>Therefore before embarking on the breeding and selection programmes, it is of vital importance to know the characteristics of the plant and more so the behavioural and physiological characteristics of the pest.
<#/>Many varieties of beans are cultivated in Kenya and in fact some are grown in localized areas. <#/>Moreover, some of the varieties were recently bred and selected by researchers to suit various growing zones of the country. <#/>Furthermore, some selected varieties have been bred for their high yield and short growing season. <#/>However, although various control methods have been used to control A. obtectus in Kenya, it is still a major pest of stored beans. <#/>In this study, it was considered important to study the behavioural relationship between A. obtectus and bean varieties under cultivation in Kenya. <#/>In particular, it was considered of scientific interest to establish how bean varietal differences affect the oviposition behaviour of the bruchids. <#/>It was hoped that certain bean varietal characteristics, physical or otherwise which significantly interfere with the bruchids oviposition behaviour would be useful to plant breeders in breeding and selecting varieties that are reasonably resistant to attack and damage by the beetles.
<#/><h> 1.20 LITERATURE REVIEW </h>
<#/>The common bean Phaseolus vulgaris has been domesticated for many years and records of its domestication date up to 700 years ago. <#/>Its origin has been attributed to Mexico ; and archeological records show that varietal characteristics have remained remarkably stable for a long time .
<#/>P. vulgaris is a polymorphic species which includes several cultivated varieties. <#/>It has thus been known by many names depending on the locality where it is cultivated. <#/>This polymorphic characteristic is dependent on physical characters such as growth habit, flower colour, size and colour of pods and seeds. <#/>It is a twining or erect annual herb with fibrous roots .
<#/>It has been cultivated in Central and South America for many centuries and is known to have reached Europe by the 16th century and was probably spread to the coastal parts of Africa by the portuguese explorers. <#/>It became established as a food crop in Africa before the colonial era . <#/>Beans grow well in most soil types from light sands to heavy clays . <#/>They also do well in areas of medium rainfall from the tropics to the temperate regions. <#/>However, excessive rain causes flower drop and increases the incidence of disease. <#/>Dry weather is required for harvesting dry shelled beans.
<#/>Beans supply edible immature pods and seeds, ripe seeds and some times leaves are used as vegetables. <#/>They are known for their high protein content as a source of food. <#/>Thus, Purseglove (1968) reported the chemical composition of beans to be 85.2 % water, 6.1 % protein, 0.2 % fat, 6.3 % carbohydrates, 1.4 % fibre and 0.8 % ash. <#/>This prompted Max Milner (1975) to recommend P. vulgaris for urgent and immediate attention by all concerned agencies and institutions as possessing the potential for significant contribution to the diets of people in major ecological zones of the developing regions.
<#/>Apart from agronomic factors, insect pests also greatly reduce bean yields. <#/>Beans are attacked by many species of insect pests, both before and after harvest. <#/>Field infestation may be contained by the plants through compensatory effects but damage in the store is often terminal. <#/>Some of the major field pests that infest beans are the bean fly Ophiomyia phaseoli and the black bean aphid Aphis fabae . <#/>While in the store, the bean seeds are further damaged by coleopterans from the family Bruchidae that results in qualitative and quantitative losses. <#/>The main bruchid species that cause severe damage are Acanthoscelides obtectus Say and Zabrotes subfaciatus Boheman (. <#/>However, of these two, A. <#/>obtectus has been shown to be the major pest of stored dry beans and it has been reported to destroy beans in various parts of the world . <#/>Although the bean bruchid is reported to have originated from central and South America, it is now cosmopolitan in distribution . <#/>It attacks beans starting from the field upto the store. <#/>Both species occur in Kenya, but A. <#/>obtectus is more widespread than the latter .
<#/>The general life cycle of A. obtectus has been studied by Hereford (1935), Davies (1935), Howe and <orth>currie (1964) and Centro Internacional de Agricultura Tropical (1986). <#/>These authors showed that females lay eggs on green bean pods or through cracks in the drying pods. <#/>The eggs may also be laid among beans in the store. <#/>Eggs are white in colour and ovoid in shape (plate 1). <#/>Fecundity per female depends on among other factors host plant, humidity and temperature. <#/>Hill (1975) found that a female bruchid laid 40-60 eggs in her life time at 28 oC and 70 % relative humidity. <#/>The eggs hatch into first instar larvae after 5 days. </I>
<#/><I> <h> MATERIALS AND METHODS. <#/></h>
<#/><h> GENERAL MATERIALS AND METHODS. <#/></h>
<#/>Six bean varieties were used for the study namely: red haricot (plate 5), <ea/>mwitemania (plate 6), rose coco (plate 7), <ea/>nyayo (plate 8), Canadian wonder (plate 9) and <ea/>mwezi <ea/>moja (plate 10). <#/>These were obtained from the local market. <#/>The varieties were identified with the help of the Horticultural Research Centre, Kenya.
<#/>Since bean varieties are known by many names depending on the locality in which they are grown, the varieties used in this study were given code names commonly used by plant breeders in Kenya and their physical appearances described (Table 3).
<#/>Bean seeds were pre-conditioned to the experimental conditions for one week before being used. <#/>Before the start of the experiments it was necessary to determine moisture contents of the seeds, to obtain proper experimental conditions and to obtain enough bruchids. <#/>Methods dealing with specific experiments are described under specific headings.
<#/>Determination of the moisture content of the bean seeds was considered important because moisture content affects growth and development of bruchids that feed on stored seeds. <#/>For average growth and development, most of them prefer seeds with about 7 -12 % moisture content . <#/>Moisture contents of the seeds were determined using the oven method . <#/>Fifty grams of bean seed of each variety was ground using an electric grinding machine at constant speed for three minutes. <#/>The ground powder was then placed in watch glasses. <#/>Each variety had six replicates. <#/>The ground powder was weighed and dried in an oven at 60 degrees centigrade for 48 hours. <#/>The watch glasses and contents were removed, cooled in a dessicator and re-weighed. <#/>The difference in weight was calculated as the percentage moisture content. <#/>The percentage moisture content of the seeds ranged between 8.85 % and 10.24 %. <#/>Temperature of the experimental room was maintained at 27 +/- 1 degree centigrade using a heater  and a lamp  (150 watts). <#/>Relative humidity was maintained at 70 +/- 5 % using s fan and a water bath.
<#/>Samples of A. obtectus used were obtained from National Agricultural Laboratories Nairobi, Kenya. <#/>Strong's (1968) method was used to rear A. obtectus for the experimental tests. <#/>The beetles were reared in a mixture of the six varieties to ensure that they did not get conditioned to one variety. <#/>750 g of the mixture and 200 unsexed one day old beetles were placed in four 1000ml plastic containers and kept in the experimental room. <#/>Beetles were left for two weeks after which they were removed by sieving, leaving larvae to develop. <#/>Four such containers were established at intervals of one month to maintain a supply of young beetles for the experiment.
<#/>For the purpose of the experiments, plastic containers (250, 500, and 1000 ml) and pill boxes were used. <#/>These were obtained from commercial suppliers. <#/>Small holes were made on the lids of the containers to allow for free circulation of air.
<#/><h> EXPERIMENT 1: INVESTIGATION OF THE EFFECTS OF BEAN VARIETIES ON OVIPOSITION SITE PREFERENCE BY A.obtectus. <#/></h>
<#/>
W2A025K
<#/><I> <h> How does a Giraffe avoid fainting or Cerebral Blackout? </h>
<#/>Having <-/succeded> in demonstrating the location and structure of the baroreceptor structure in the giraffe, we then turned our attention to the first of the three questions raised above namely, how does the giraffe sustain an adequate blood flow to the brain despite its long neck. <#/>It may be recalled that other workers had already demonstrated that the animal has a relatively high central arterial pressure in the range of 350/250 mm Hg. <#/>The blood pressure profiles noted when the tip of the catheter is progressively <-/withrawn> from the heart cephalad, shows a gradual drop so that at the level of the brain the pressure is about 12O/9OmmHg. <#/>Apparently this is fairly close to the brain perfusion pressure in man. <#/>For this reason, the type of high pressure in this animal, has been referred to as adaptive or gravitational hypertension.
<#/>These earlier studies led to the conclusion that the pressure generated by the giraffe heart is adequate to maintain blood supply to the brain without recourse to any <-/auxillary> mechanisms, such as a siphon effect or a peristaltic wave along the arteries of the neck. <#/>In the course of our studies we came across some evidence, though subtle, suggesting that a rise in pressure of only 50 mm Hg when the head of a recumbent anaesthetised giraffe was raised for a vertical distance of 150 cm above the heart level, could not suffice to maintain blood pressure at the brain level within limits against a calculated hydrostatic pressure of 110 mm Hg . <#/>This indicated to us that some other mechanisms yet to be fully elucidated may come into play.
<#/>Faced with this dilemma, we were led to believe that some of the mechanisms by which the giraffe ensures an adequate cerebral perfusion pressure, and protection of the brain when it lowers its head to drink, may be a function of the hypertrophied wall of the left ventricle, the morphology of the blood vessels and appropriate barostatic reflexes. <#/>Our studies revealed that the carotid arterial system of the giraffe has a unique structure which other workers had failed to appreciate in explaining the adaptive mechanisms to gravitational stresses in the giraffe . <#/>For example, near the root of the neck, the carotid arteries have the structure of an elastic artery in the luminal third and a prominent muscular structure in the outer <-/twothirds>. <#/>Towards the head, the luminal elastic zone diminishes and is replaced by smooth muscle. <#/>Furthermore, the smooth muscle in the outer part of the tunica media is organized in form of conspicuous bundles, separated by septa of fibrous tissue. <#/>These septa continue into the tunica adventitia and bring small vessels with them that nourish the muscular tissue in the tunica media. <#/>This mode of transition of the vessel wall from an elastic artery to a muscular artery is at variance with the classical textbook accounts, in which it is stated that elastic tissue persists on the outer side and smooth muscle appears on the luminal side.
<#/>Electron microscopy revealed a close apposition of the smooth muscle cells in the outer layer of the vessel wall and sometimes formation of nexuses . <#/>The latter are areas of electrotonic coupling between adjacent cells, so that membrane depolarisation can pass from one cell to another. <#/>The individual cells showed a large content of myofilaments and paucity of synthetic organelles. <#/>This suggested to us that these cells have a preponderantly contractile function and diminished fibrosynthetic function. <#/>It is generally believed, that the smooth muscle cell is the only type of cell found in the tunica media of arteries. <#/>As such, it must be the cell responsible for the production of the extracellular components, such as collagen and elastic fibres in addition to its contractile function . <#/>In support of this dual function of the vascular smooth muscle, is the demonstration in numerous studies that vascular smooth muscle cells in elastic arteries contain both myofilaments and synthetic organelles. <#/>Consequently, these cells have been referred to as myofibroblasts. <#/>In the giraffe carotid arterial system, myofibrofiblast-like cells are found only in the luminal elastic zone, where they occur between the elastic lamellae, while typical smooth muscle cells occupy the outer layers of the tunica media . <#/>Another cell with fibroblastic characteristics occurs in the outer two-third of the tunica media, particularly within the connective tissue septa between the bundles of smooth muscle .
<#/>Our findings on the giraffe made two important contributions to knowledge: first, that the statement that the smooth muscle cell is the only cell type in the tunica media of blood vessels is no longer tenable; and second, that in the giraffe carotid artery, the mode of arterial transition from elastic to muscular arteries differs from that described in many classical textbooks of histology. <#/>Our study revealed also another notable feature of the giraffe arteries; i.e., the endothelium is anchored to the underlying tissues through a multilaminated basement membrane which we thought, is an adaptation to elevated luminal shearing . <#/>Related to this is the fact that a similar, but poorly organized fibrillar material forms the earliest noticeable structural component in the subendothelial zone of the vessels of spontaneously hypertensive rats . <#/>Though this material had been regarded as a pathological change, its natural appearance in the giraffe may indicate otherwise- it forms part of the functional adaptation of the arterial wall to elevated luminal shearing in conditions of raised blood pressure.
<#/>We kept on wondering whether there are any structural differences between the adult and fetal giraffe carotid arteries and other vessels. <#/>This is because whereas fetal giraffes develop in a quasi-weightless <-/mileu>, postpartum giraffes must contend with increasing load bearing in their dependent tissues as they grow to heights over 5 metres and to weights over 1000 kilograms. <#/>We were not allowed to kill pregnant mothers during our numerous culling expeditions. <#/>Our anxiety was, however, rewarded one day when someone from the Nairobi National Park turned up in the department with the magical specimen- a full term fetal giraffe whose mother had died in "labour" at the Zoo. <#/>A detailed histological analysis of material obtained from the common carotid arterial system revealed that the proximal part of the common carotid artery has the features of a typical elastic artery . <#/>The tunica media consists of uniformly arranged and alternating elastic lamellae in its entire thickness. <#/>This is in sharp contrast to the transmural zonation observed in the adult vessels, in which elastic lamellae are only confined to the luminal <-/onethird>, while the outer two-thirds contain a large amount of smooth muscle. <#/>This suggests that the smooth muscle in the outer <-/twothirds> of the tunica media appears postnatally.
<#/>The question remained, however, whether the large content of smooth muscle noted in the giraffe carotid arteries is a unique adaptation to the attendant haemodynamic stresses. <#/>To answer this question we decided to study the vertebral artery, which is another artery found in the neck. <#/>In humans, this vessel is one of the two main sources of blood supply to the brain. <#/>Gross anatomical studies in the giraffe and other members of the Artiodactyla group had shown that this artery does not supply the brain . <#/>It had also been noted that the first branch of the common carotid artery at the base of the head sends a branch which establishes a direct anastomosis with the vertebral artery . <#/>Lawrence and Rewell (1957) were the first to describe this artery in the giraffe and <-/contrigued> that it constituted the major difference between the giraffe and other Artiodactyls. <#/>The question has been raised in our studies whether the function of this artery is to establish a direct anastomosis, and therefore a collateral circulation between the carotid and vertebral arteries. <#/>It seems to us that under normal circumstances, this artery is responsible for the vascular supply of the upper one third of the neck. <#/>The evidence pertinent to this conclusion stems from three important findings: first, this artery gives off a prominent muscular branch before entering through the alar foramen of the atlas; second, the internal vertebral branch after passing through the alar foramen makes a sharp turn and descends caudally within the vertebral canal to anastomose with the internal branch of the vertebral artery; and third, the vertebral artery terminates at the junction between the second and third cervical vertebrae by dividing into an internal and an external branch. <#/>The internal branch enters through the intervertebral foramen and runs horizontally within the vertebral canal before giving off an ascending branch that anastomoses with the internal vertebral branch of the first dorsal branch of the carotid artery. <#/>For this reason, this branch of the carotid artery may be more appropriately named "accessory vertebral artery." Thus, in the giraffe, as in most other Artiodactyls, the vertebral blood does not participate in the supply of cephalic structures because it is confined to the neck-region by the pressure barrier in the carotid-vertebral anastomosis. 
<#/>Histological studies revealed that the proximal part of the vertebral artery has the features of an elastic artery, while its cranial segment has the features of a typical muscular artery . <#/>Compared with the carotid artery, the vertebral artery has a thinner wall conceivably on account of its smaller calibre. <#/>The transition zone from elastic to the muscular parts lies at the level of the sixth cervical vertebra. <#/>Here the tunica media shows a transmural differentiation into a luminal muscular zone and an outer elastic zone. <#/>This is in contrast to the pattern observed in the common carotid artery in which the muscular tissue occupies the outer portion of the tunica media and elastic tissue the luminal portion. <#/>It resembles, however, the mode of arterial transition from elastic to muscular arteries described in many classical textbooks of histology . <#/>These findings led us to conclude that vertebral and carotid arteries in the giraffe may be subjected to different haemodynamic demands. <#/>It is conceivable that whereas the pressure developed by the heart is adequate for perfusion of the areas supplied by the vertebral arteries, a peripheral <-/auxillary> mechanism may be necessary in the case of the carotid arterial system; and this may be reflected in its mural remodelling process during the postnatal growth and development which is characterized by appearance of smooth muscle on the outer part of the vessel wall.
<#/>The camel is another animal with a long neck just like the giraffe. <#/>In fact the generic name of the giraffe - camelopardalis means the camelleopard. <#/>This is in reference to its long camellike neck, and reticulated leopard-like skin. <#/>However, whereas the giraffe's neck is held vertically as it browses on trees, that of the camel undulates horizontally. <#/>Hence, under normal circumstances, the camel's brain is more or less at the same height as the trunk and hence the heart. <#/>We wondered whether there are any structural differences between the common carotid arteries of the giraffe and camel in view of these postural differences of their necks. <#/>In particular we wanted to know how the structure of the blood vessels in the neck of the camel change from the heart peripherally. <#/>To our delight, we noted that in the camel, the change from elastic to muscular parts of the carotid artenes is quite the opposite of the pattern observed in the giraffe, but resembles the latter's vertebral artery. <#/>Therefore, the area of transition shows a transmural zonation into a luminal muscular segment and outer elastic segment.
<#/>The above observations made in the camel brought us fairly close to what we thought was a unique and significant finding in the giraffe: that the large content of smooth muscle noted within the carotid arteries could, in deed, be a special adaptation to gravitational stresses. <#/>However, there was one missing piece of evidence in this puzzle, i.e., does this smooth muscle have an autonomic or motor nerve supply to trigger its contraction? <#/>Other studies based on the small laboratory animals had confirmed that autonomic nerves on blood vessels maintain a basal tonic state so that when an innervated vessel is subjected to sudden stretch, it responds in a more myogenic fashion unlike a <-/dennervated> vessel which acts more like a flaccid tube. . .
<#/></I>W2A026K
<#/><I> <h> ACHIEVING SUSTAINABLE FOOD PRODUCTION IN AFRICA: ROLES OF PESTICIDES AND BIOLOGICAL CONTROL AGENTS IN INTEGRATED PEST MANAGEMENT </h>
<#/><h> INTRODUCTION </h>
<#/>Between 1980 and 1986, Africa's population grew by slightly over 3% per year, while food production rose by 2.3% and total agricultural production by 2.4 % . <#/>There is therefore a wide gap between food demand and supply and the gulf between starvation and adequate feeding continues to widen. <#/>Estimates have shown that Africa's grain deficit could rise from 6 M tons in 1975 to 44 M in the year 2000, representing decline in self sufficiency from 86 to 61 % . <#/>The factors responsible for low food productivity in Africa are numerous. <#/>They include drought, low fertility soils and agricultural pests, as well as vectors of diseases, such as tsetse and ticks, which spread devastating diseases to livestock. <#/>Only 3-6% of the landmass in eastern and central Africa receives more than 1250 mm of rainfall per year. <#/>However, this rainfall is highly variable both in timing and duration . <#/>In west Africa, for instance, high fertility soils represent only 10.5 M ha. <#/>compared with 180 M ha. <#/>of low-to-medium fertility soils, and 243 M ha. <#/>of very low fertility soils. <#/>Another serious problem restricting food productivity is insect pests; this paper focuses primarily on this problem and its solutions. <#/>It is estimated that although 80% of all animals are insects, less than l % of insects are pests .
<#/>Insect pests attack agricultural crops, in the field and in storage, causing considerable losses of agricultural produce. <#/>Ever since the dawn of cropbased agriculture, control of pests, diseases and weeds has been a central objective of crop production practices. <#/>Thus, pest management is an ancient problem. <#/>For instance, over 2500 years BC, the Sumarians used sulphur compounds to control insects and mites; crude wooden implements, including hoes, were used to control weeds. <#/>The Chinese controlled insect pests by adjusting crop planting times, and by exploiting natural enemies several centuries before the birth of Christ . <#/>On worldwide basis, crop losses to all pests (insects, diseases and weeds) are estimated to be nearly 48%; this includes 35 % preharvest and 20% postharvest losses, whereas in USA alone preharvest and postharvest losses are estimated to be 33% and 9%, respectively.
<#/>The losses of major agricultural crops caused by field pests are estimated to average 42% in Africa and 43% in Asia; these are conservative overall estimates, because in some tropical developing countries, losses of 94-97% have been reported. <#/>Cowpea yield losses at Samaru in Northern Nigeria for instance, were estimated at 92%, 94% and 97% in 1971, 1972 and 1973, respectively ). <#/>Approximately 30% of rice in Sierra Leone and 25-45% of maize in Ghana are destroyed by pests during storage, whereas in Northern Nigeria 50-60% of stored cowpea is destroyed after only 6 months of storage. <#/>These losses <-/aggrevate >the food deficit situation in Africa and drastically reduce the financial returns to farmers and the export earnings of the countries concerned.
<#/>Vectors of livestock diseases such as tsetse also limit food productivity. <#/>Tsetse affects 10 M km 2 in 36 African countries, an area equivalent to one third of the continent's total land mass or half of its inhabited area. <#/>The downward trend in food productivity which became apparent in early 1970s has now made almost half the members of the Organization of African Unity dependent on food aid . <#/>Sustainable agricultural development aimed at increasing food productivity, while at the same time preserving the environment, should therefore be a priority for Africa. <#/>Sustainable agricultural development has been defined as "The development that will enable mankind to meet the needs of today without compromising the ability of future generations to meet their own needs" .
<#/>Insecticides have been used in Africa primarily for the control of pests of cash crops and vectors of human and animal diseases. <#/>Compared to developed countries, however, the quantities of pesticides used in Africa are relatively small, although even in Africa there is an upward trend in the importation and use of pesticides . <#/>It is estimated that importation of pesticides into Africa has risen by at least 100% over a period of 15 years prior to 1989 . <#/>Now is therefore the right time to warn farmers of the hazards of overuse of pesticides, so that Africa can avoid repeating past mistakes of other countries. <#/>The solution is the development of integrated pest management (IPM), an excellent example of a biological approach to sustainable agricultural production. <#/>This paper deals with the problems associated with heavy use of chemical pesticides, and how they can be avoided through adoption of IPM.
<#/><h> THE ERA OF CHEMICAL PESTICIDES </h>
<#/>The era of synthetic pesticides began just after World War II when DDT was introduced to the world market in 1946. <#/>Since DDT and similar compounds were used successfully in pest control, more and more pesticides were introduced into the world market. <#/>The United States is the world's largest pesticide consumer utilizing 35-45% of total world production of these chemicals. <#/>Western Europe uses 23%, Eastern Europe 15%, Japan 8% and all developing countries 7-8% . <#/>It is estimated that there are about 1000 chemical pesticides in the world market and that more than 250,000 tons are sold annually. <#/>Estimates from 38 developing countries show that of all pesticides, insecticides are the most used. <#/>The proportions of pesticides used in 1973 were 12.2% insecticides, 30.4% fungicides and 3.4% herbicides . <#/>The average amount of pesticide used annually in terms of weight is about a pound for every man, woman and child living on earth. <#/>However, only about one fifth of this amount is used for every person in third world countries . <#/>In USA, about 1 billion pounds of pesticides are used each year.
<#/>Pesticides are used in developing countries mainly for the control of agricultural pests, e.g. <#/>locusts, armyworm, cocoa, coffee or cotton pests, and to a much lesser extent (approx. <#/>10%), for the control of insect vectors, e.g. <#/>mosquitoes, tsetse, blackflies, ticks, etc . <#/>Indeed, pesticides brought about the promise of an effective weapon against pests that devastate crops and insects that spread diseases. <#/>In Britain, for instance, where food production relies heavily on pesticides, these chemicals have helped to increase production by more than 2% a year for the past two decades , . <#/>It is estimated that removal of all pesticides from US agriculture would raise crop losses caused by pests from 33 to 42% . <#/>In the third world, chemical pesticides have also improved crop production significantly. <#/>For instance, chemical weeding of groundnuts, 2 and 4 weeks after sowing has been reported to increase yields by as much as 179%. <#/>Similarly, experiments at IRRI, Philippines, showed that rice plots protected by insecticides yielded an average of 2.7 tons/ha. more than unprotected plots, almost doubling the yield. <#/>In Ghana, the use of chemical pesticides to control cocoa pests increased yield by up to 244% in 1960 and saved 70,000 tons from destruction . <#/>This "Chemical Era of Crop Pest Management" therefore, has seen great strides in crop production in certain countries. <#/>Indeed, the achievements of this era have been called "The Green Revolution" and are responsible for the current food surpluses in many countries of the world . <#/>In the field of public health, especially in malaria control, chemical pesticides have achieved wonderful results. <#/>A global malaria eradication policy adopted by the WHO in 1955 is estimated to have prevented 2000 M cases of malaria and saved 15 M lives by 1970 . <#/>In spite of all these achievements, serious problems started to emerge after about one decade of heavy and widespread use of chemical pesticides.
<#/><h> THE PROBLEMS CAUSED BY CHEMICAL PESTICIDES </h>
<#/><h> Pest resistance to chemical pesticides </h>
<#/>Individuals resistant to pesticides do not simply arise as a result of exposing insects to sublethal doses of insecticides, nor through mutation; a very small number of resistant individuals already exist in populations before any insecticide use. <#/>When insecticides are applied, resistance confers selective advantage to resistant individuals; their susceptible neighbours are killed, but genetic selection favouring the increase of resistant individuals and at some point the population, is said to have developed resistance.
<#/>Resistance to DDT appeared in houseflies as soon as DDT was introduced in 1946. <#/>Four years later resistance appeared in mosquitoes, and by 1980, there were 432 species of arthropods resistant to at least one pesticide (171 of medical and veterinary and 261 of agricultural importance). <#/>The current figure must be much higher, considering that the resistant arthropod species more than doubled between 1960 and 1980. <#/>By 1976, at least seven species of rats had developed resistance to rodenticides and by 1984, 150 species of plant pathogens and 50 weed species had developed resistance to pesticides . <#/>Unfortunately, pests seem to develop resistance much faster than their natural enemies. <#/>Out of 225 resistant arthropod species documented until 1971, only four were natural enemies of pests. <#/>In the Gezira cotton scheme in Sudan, the quantities of pesticides used and the number of spraying per season have steadily increased, e.g. from one spraying per year in 1959 to 9.3 in 1978, consequently, production costs quadrupled in 10 years, while yields fell by 40%. <#/>In the 1950s, pesticides in cotton fields in Central America were applied eight times per season, but with the development of resistance, applications increased to 40 times by the early 1970s . <#/>It is estimated that crop losses from insect pests in USA increased nearly twofold from 1940s to 1970s in spite of a tenfold increase in insecticide use .
<#/><h> Cost of chemical pesticides </h>
<#/>The average price of common insecticides has increased by over 20% per year since 1970. <#/>Developing countries are finding it increasingly difficult to afford them, especially because they are bought in foreign currency. <#/>In the Gezira cotton scheme in Sudan, for instance, the cost of importing insecticides from 1966/67 to 1980/81 increased by over 1400% .
<#/><h> Pest resurgence </h>
<#/>Widespread use of pesticides upsets the equilibrium between pests and their natural enemies, thereby allowing pests to multiply without natural checks. <#/>Natural enemies of insect pests often take longer to recover than target pests. <#/>Hence, populations of target pests tend to explode to unprecedented numbers after pesticide application. <#/>This is partly because natural enemies suffer two blows; the mortality caused by pesticides and the stress due to reduced food (pest) supply . <#/>With this danger in mind, the famous insect physiologist, Sir Vincent Wigglesworth suggested as early as 1945 that an insecticide killing 50% of a pest population might well be better than one killing 95% plus its natural enemies .
<#/><h> Secondary pest outbreaks </h>
<#/>Pesticides may kill large numbers of natural enemies of a species other than the target pest. <#/>It is estimated that apart from the 5000-15,000 recorded pest species, there are perhaps 10 times as many potential "unnoticed" pests. <#/>When these pests, previously unnoticed because their numbers were kept low by natural enemies, reproduce unhindered, they may lead to "secondary pest outbreaks", the opposite of the desired effect. <#/>When cotton production started in Central America during the first quarter of the twentieth century, there were only three pests: the red boll weevil a major problem, the leafworm, and the desert locust. <#/>The farmers controlled them using natural methods. <#/>In the 1950s, intensive use of machinery began and chemical pesticides were applied eight times per season to increase crop yield. <#/>By the mid 1950s, three new pest species had appeared due to increased pesticide use. <#/>In response, farmers used 28 applications per season, and also used an increasing number of pesticides. <#/>Two pests ceased to be important, but were replaced by four new ones, including armyworm and whitefly. <#/>The combination of new pests and pest resistance, forced farmers to increase pesticide application till pest control accounted for 50% of the cost of cotton production, and even then, yields started falling. <#/>By the 1970s cotton farmers had to deal with important pest species. <#/>Likewise, in the Gezira cotton scheme in Sudan, several new pests have emerged due to heavy insecticide use. <#/>Another example is in the Ahero rice irrigation scheme in western Kenya, where the organophosphate Dimecron was sprayed against rice stem borers. <#/>Dimecron also eliminated larvae of Anopheles gambiae and their predators, so that the next peak of A. <#/>gambie was much higher than before spraying .
<#/></I>
W2A027K
<#/><I> <h> INTRODUCTION </h>
<#/>Malaria remains the leading public health problem in many tropical countries. <#/>Nearly 90 million people were estimated to be affected by malaria in 1981. <#/>In 1974, malaria ranked third among the leading causes of death in Kenya . <#/>Malaria ranges from hyper- to holoendemic in Western and coastal regions of Kenya and spleen rates above 75% among children under 10 years of age are common .
<#/>It has been noted that only about 1-5% of children develop severe, life-threatening disease in areas where all children will be infected during infancy and childhood. <#/>The mortality of severe malaria is high, and many patients die shortly after receiving treatment . <#/>The clinical characteristics of malaria differ between different geographical areas and within each area, being influenced by factors such as seasonal variation in transmission, age of the infected patients, species and intensity of parasitemia, access to antimalarial treatment and other probably unknown variables . <#/>It is therefore important that the factors which contribute to the severity of infection be examined. <#/>In addition, the level of community education and cultural values may contribute toward the development of severe disease .
<#/>In this regard, the important questions to be considered include:- (a) What are the vector-related factors associated with the severity of malaria as a disease attacking a population which is exposed to intense transmission? <#/>(b) Is there any association between severity of disease and vector infectivity? <#/>(c) Are individuals residing in households with higher entomological inoculation rates more likely to develop severe clinical malaria? <#/>In order to answer the above questions a stepwise series of field studies to examine natural variation at different micro-environmental levels (house to house) will be conducted at selected sites. <#/>Kilifi District is an area with many differing ecotypes. <#/>It is served by 2 government hospitals, 6 health centres and 40 dispensaries. <#/>Malaria vector control has not been attempted in this area to date.
<#/>A KEMRI-Oxford University team has established that the distribution of severe and non-severe cases of malaria come from large area surrounding Kilifi district hospital and normally cluster in time and space. <#/>Most of the cases occur from June to September and from December to January . <#/>It is believed that there are geographic differences in levels of malaria transmission. <#/>Attempts will be made to relate entomological variables to clinical and parasitological findings in order to identify risk factors at the household level according to ecological zones. <#/>The knowledge gained should be helpful in designing more effective control measures.
<#/>A KEMRI-Oxford University team in 1985-86 reported parasite rates of about 50.7% (N= 4,654), with P. falciparum predominating (P. falciparum: P. malariae: P. ovale, 79.5% : 20.8% : 1.6%). <#/>P. falciparum infections rates ranged from 4% to 92% in children 2-9 years of age, demonstrating considerable variation among villages. <#/>Studies of Bancroftian filariasis conducted in rural site near Kilifi more than ten years ago indicated that Anopheles fauna inside houses consisted of 95% of An. funestus and 5% An. gambiae s.l. .
<#/>The purpose of this study is to measure vector specific inoculation rates and vector dynamics as it relates to the severity of disease. <#/>These studies will be closely integrated with the clinical epidemiological and entomological studies currently being conducted in Kilifi District.
<#/><h> LITERATURE REVIEW </h>
<#/>Malaria transmission rates can be influenced by a number of factors including innate host preferences, host numbers, and host accessibility to mosquitoes. <#/>Human contact with mosquitoes may be altered through cultural practices which affect the abundance and location of both human and domestic animals. <#/>For example, seasonal migrational habits bring humans into closer contact with vectors and have been correlated to differences in malaria parasite prevalence in Thailand . <#/>MacCormack (1984) reported a diminished mosquito attack rate on humans when domestic animals are impounded near or in houses in <-/savanna> Africa, while Coluzzi (1984) reported higher human blood indexes (HBIs) and sporozoite rates for An. gambiae s.s and An. arabiensis in villages with a higher ratio of humans to cattle. <#/>Personal protective measures (i.e screening, bednets, repellants and tightly constructed houses) have been found to lower the HBIs, sporozoite rates, entomological inoculation rate and biting rates of vectors with a corresponding drop in the incidence of P. falciparum in children .
<#/>Considerable information about malaria transmission exists for Western Kenya around the shores of Lake Victoria. <#/>However, only limited information is available for the coast region . <#/>An. gambiae s.l and An. funestus are the two main <-/anthrophopilic> malaria vectors throughout Kenya. <#/>Generally, An. gambiae is associated with seasonal rainfall and transmission by An. funestus is associated with drier periods. <#/>Endemicity level of malaria in the coastal zone of Kenya range between hyper- to holoendemic. <#/>There are variations of the vectorial capacity and transmission patterns by season and micro-ecology. <#/>Besides the An. gambiae complex and An. funestus, studies done on the Kenya coast about three decades ago revealed that several other Anopheles species not considered to be malaria vectors are present . <#/>More recently, Mosha and Mutero (1982) and Mosha and Petrarca (1983) carried out ecological studies on the examination of An. merus a salt-breeding species of the An. gambiae complex. <#/>Currently there is an on-going study on vectors whose overall goal is to identify vector-related factors affecting malaria transmission and the clinical severity of malaria in children. <#/>The proposed study will thus be integrated into the current study.
<#/><h> Anopheles gambiae complex. <#/></h>
<#/>There is considerable evidence that malaria in Africa is primarily transmitted by the An. gambiae complex and An. funestus . <#/>An. gambiae Giles, formerly regarded as a single species has been recognized through genetic techniques as comprising of six, morphologically indistinguishable sibling species . <#/>These include An. merus, An. gambiae s.s, An. arabiensis, An. melas, An. quadriannulatus, and An. bwambae. <#/>Three sibling species of An. gambiae complex have been identified in Kenya . <#/>These include An. gambiae s.s., An. arabiensis and An. merus. <#/>An. merus, a salt-water breeding species occurs mainly in some coastal areas .
<#/>The distribution of the An. gambiae complex is well known in Western Kenya, whereas there is very limited information for coast region. <#/>Generally, its distribution is based on relatively few chromosome identifications from adult females.
<#/><h> Sporozoite infection rates </h>
<#/>The three sibling species of An. gambiae complex found in Kenya show considerable variation in their vectorial capacity . <#/>In Western Kenya, Service et al (1978) reported higher malaria infection rates in An. gambiae s.s than for An. arabiensis, while Mosha and Petrarca (1983) hardly found any sporozoite infections in An. merus. <#/>White et al (1972) reported sporozoite rates of 4.23% in An. gambiae s-s and 0.32% in An. arabiensis at Sengera, Tanzania (13.2 times more frequent in An. gambiae s.s). <#/>In Kenya, Highton et al (1979) reported sporozoite rates of 5.33% in An. gambiae s.s and 0.33% in An. arabiensis. <#/>However, Joshi et al (1975) reported sporozoite rates of 8% in An. gambiae s.s and 7.8% in An. arabiensis at Ahero, Kano plains, Kenya. <#/>These rates were not significantly different. <#/>Beier et al (1987) recorded sporozoite rates of 10.9% and 10.2% in An. gambiae s.l and An. funestus respectively.
<#/>Infection ratios among the three sibling species of the complex on the Kenya coast have not been examined, hence the purpose of this study.
<#/><h> Human blood index </h>
<#/>Although the three sibling species can reach high vectorial capacities for malaria, the host choice behaviour of the species is quite different and varies from village to village depending on the ratio of animals to humans. <#/>For instance, in areas where cows outnumber men, An. gambiae s.s tends to show higher human blood indices and develop higher malaria sporozoite rates than An. arabiensis (Coluzzi, 1984). <#/>In Western Kenya, studies on precipitin tests indicate that 95.8% of An. gambiae s.s and 92.4% of An. arabiensis obtain blood meals from man , while Elisa tests  indicated 87.2% of An. gambiae s.I and 99% of An. funestus to have fed on man.
<#/><h> Seasonality </h>
<#/>An. gambiae s.s and An. arabiensis are closely associated with rainfall. <#/>In Western Kenya, Joshi et al (1975) reported that the proportion of An. arabiensis increased in the dry season although its absolute population decreased. <#/>The proportion of both species can change drastically from year to year due to climatic changes . <#/>There is no information about seasonality of vectors on the <-_Kenya><+_Kenyan> coast.
<#/><h> JUSTIFICATION </h>
<#/>In areas of stable malaria endemicity, the prevalence of malaria infection approaches 100%. <#/>There is clinical progression from uninfected to infected to clinically ill to severe illness to death. <#/>Thus:-
<#/>Uninfected ------ > infected ----- > clinically ill ----- > severe illness ----- > death.
<#/>Most epidemiological studies focus on understanding the first two of these transitions. <#/>Less is known about causes of subsequent transitions in the development of clinical malaria and more so as it relates to vector-related causes. <#/>The relationships between parasite, vector, and man have been applied in developing antimalarial strategies. <#/>However, difficulties have been encountered in using such applications owing to the <-/inadequancy> of baseline data and/or the lack satisfactory estimates of some factors governing transmission of the disease. <#/>In the proposed study, vector related epidemiological factors considered as potential determinants of severe malaria will be evaluated.
<#/>The risk of infection for individuals living in an endemic area depends upon exposure to infected Anopheles and therefore, it hypothesized that the distribution of clinically severe malaria cases should be related to the distribution of infected Anopheles vectors.
<#/>The epidemiological situation of malaria in a country or locality is by no means uniform and so the number of clinical episodes of malaria experienced by an individual in a household should be related to exposure levels to infected Anopheles.
<#/><-_To><+_For> most effective control it is essential to identify epidemiological factors in terms of the following parameters; vector characteristics (relative <-/abudance> of species, gonotrophic cycles and survival rates), feeding patterns, sporozoite rates, and house factors. <#/>These factors are of considerable epidemiological significance in the transmission of disease.
<#/><h> OBJECTIVES </h>
<#/>1. <#/>To determine anopheline species composition and abundance in relation to malaria transmission intensity and illness at two ecologically distinct sites.
<#/>2. <#/>To assess the relationship between the entomological inoculation rates in households with children having severe malaria and households with children having mild malaria.
<#/>3. <#/>To identify vector related features of households which contain cases of severe and non-severe malaria.
<#/><h> EXPERIMENTAL DESIGN AND METHODS </h>
<#/>The current WHO funded case control study has documented clinical disease in certain households, therefore defining households as generating degrees of severe illness. <#/>These will be used as sampling households within an area which has been accurately mapped and enumerated as part of a study to identify socioeconomic and behavioural factors in the determination of severe disease . <#/>Prospective recruitment of severe, non-severe and community controls will continue until May 1992, and thus carrying out the study in these selected areas will generate further households. <#/>Prospective parasitological screens for malaria parasites and active morbidity surveillance in both adults and children will be carried out monthly in the identified households. <#/>In the same households sampling for vector dynamics will be done. <#/>The Principal investigator will be trained in the development of immunological techniques for vector field studies.
<#/><h> Study area </h>
<#/>Studies will be conducted in Kilifi District, Coast province. <#/>Kilifi borders the Indian ocean and lies about 400 km south of the equator between latitudes 3 and 4 degrees. <#/>There is dense forest vegetation as well as savannah; elevation ranges from 0 to 400 m above sea level. <#/>Rainfall averages >1,000 mm per year with a long rainy season from April to June and a short rainy season in September and October. <#/>It is hot and humid all the year round with daily temperatures ranging from 22 to 30 degrees centigrade. <#/>Within the study area there are an estimated 50-70,000 people, mostly subsistence farmers growing mangoes, maize, cassava, cashew and coconut. <#/>The predominant ethnic group is the Mijikenda of which about 70% belong to the <-/Giriyama> tribal group. <#/>This area was selected based on accessibility to Kilifi town where there is a district hospital; about 75% of in-patients with severe malaria reside within the study area. <#/>Most are referred from out-patient facilities in the district. <#/>In the same area the KEMRI-OXFORD team is carrying out clinical epidemiological studies on the severity of malaria in children.
</I>
W2A028K
<#/><I> <h> Discussion of abortion </h>
<#/><h> Definitions </h>
<#/>With the advances in medical science and health care delivery systems in many parts of the world, there has been a corresponding improvement in various <-/morbidities> and <-/mortalities>. <#/>Most notable is the improved survival of new-born babies, especially the preterm. <#/>As a result, the definition of abortion and viability of a foetus has undergone continuous revision, from the original 28 weeks of gestation cut-off point down to 24 weeks and then down to 20 weeks of gestation or a foetal weight of 500 grams.
<#/>This means that studies done in the same place over different periods (say, 1975 and 1985) may not be comparable in all aspects since their cut-off points are different. <#/>Secondly, even studies done recently may employ different definitions of abortion because the researchers were not familiar with the changes or for some other reasons. <#/>As evidenced from the studies done in Kenya so far, some workers have continued to use the 28-week cut-off point, while others have used the 20-week or 500-gram foetal weight.
<#/>Most of the earlier studies used the older definition. <#/>However, some of the more recent studies have continued to use the same cut-off point. <#/>One may appreciate the dilemma faced by researchers working within the community in as far as the cut-off points are concerned, especially in remote places where most of the abortions are done very late in pregnancy. <#/>It is not clear, however, why the hospital-based ones have continued to use it. <#/>Looking at the studies done in Kenya with regards to definition of abortion, one notes a lot of disparity. <#/>While they may not all be comparable in a number of aspects, they have nevertheless helped in highlighting abortion, its potential magnitude and related problems. <#/>Only a few of the more recent studies have used the latest definition of 20 weeks or 500-gram foetal weight. <#/>Some of the studies did not specify the gestational ages, either because they were not specifically looking at this aspect of abortion, or all of their study population were of low gestational periods because of the type of technique or study.
<#/>The larger the gestational age at the time of termination, the higher the chances of serious complications such as haemorrhage, perforation of the uterus and sepsis. <#/>Also, the wider the gestational age range the higher the incidence will appear to be. <#/>
<#/>Definitions help in standardizing methodology and ensuring comparability of results (data). <#/>These points are worth taking into consideration when looking at the different study results, otherwise there may be a lot of bias and wrong conclusions being drawn.
<#/><h> Magnitude and regional variations </h>
<#/>The actual magnitude of abortion is not and may never be known. <#/>It is difficult if not impossible to establish it on a hospital or local let alone national level. <#/>Abortion is still regarded as secret by most people, mainly because of its social, moral and legal connotations. <#/>Even when spontaneous, very few people talk openly or even privately about it. <#/>Secrecy becomes even more pronounced when the abortion is induced.
<#/>Abortions are usually induced or done secretly and do not get on to any record in hospitals, clinics or the community. <#/>The cases that normally get to the hospital are considered the tip of the iceberg. <#/>They are the few women who sustain some form of complication — severe haemorrhage with or without shock, sepsis, organ injuries — which may compel them to seek medical attention (if they survive the ordeal long enough to reach a health facility). <#/>A majority of the induced and some of the spontaneous abortions do not sustain any complications warranting medical attention. <#/>Some of the abortion cases may be admitted with other diagnoses such as urinary retention, acute renal failure acute cardiac failure, severe anaemia, pelvic abscess, tubo-ovarian mass, tetanus, pneumonia, subphrenic abscess, deep venous thrombosis, malaria, pyrexia of unknown origin or dysentery. <#/>Since the patients may not give or may not be able to give appropriate histories, the truth may never be known. <#/>Abortion cases may also be missed in a very busy medical institution, or when the attending doctors overlook the possibility of induced abortion leading to the patient's presenting symptoms. <#/>These omissions are not unusual even in the best of institutions. <#/>The results are inaccurate figures and incidence/proportions of abortions as well as misrepresentation of the related complications. <#/>
<#/>There may also be considerable arbitrary regional variations (either hospital to hospital, or location to location) because of record-keeping or because there are different numbers of women in the sexually active bracket (15 - 45 years) in some areas. <#/>There may be more induced abortions, and since the techniques used are more hazardous more women sustain serious complications and go to hospital. <#/>The availability and accessibility of a medical facility is another factor as are the different values attached to fertility, marital customary values/practices, sexual relations and taboos, or educational level of the woman. <#/>There may also be more abortion service providers in the larger urban centres.
<#/>While it is generally accepted that abortion and especially induced abortion is more common among young single urban women, recent studies have shown that this is not invariably so.
<#/>Some of the hospital-based studies have shown that the incidence of abortion varies considerably even in the same institution. <#/>Nyakeri found an incidence of 43.3%, Aggarwal et al. reported it to be 60.5% of all gynaecological admissions, while Fomulu had 51.9%. <#/>Mutungi obtained a figure of 50.2% of all acute gynaecological admissions and Omuga got an incidence of 61.4% of all gynaecological emergency admissions. <#/>Mati stated that the total number of abortion admissions rose from 1,838 in 1971 to 3,048 in 1975 at the same institution. <#/>Variations have also been noted in the studies done elsewhere. <#/>Njuki reported an incidence of 62.5% of all acute gynaecological admissions at the Nakuru Provincial General Hospital, while Lema et al. had different incidences in the eight hospitals under study: 13.4% at Kisii District Hospital, 28.1% at Kitui, 35.0% at Bungoma, 42.3% at Kajiado, 51.6% at Chogoria and 74.5% at Malindi District Hospital.
<#/>The denominator used in these studies varied from acute/emergency gynaecological to total gynaecological admissions. <#/>Furthermore, the number and types of gynaecological admissions vary depending on the location and availability of services and expertise to treat them. <#/>The more equipped the hospital is in terms of specialized facilities and expertise, the more and varied the admissions. <#/>This may lead to lowering of the incidence of any particular condition.
<#/>The period of study may also influence variation in incidence as there are some peak and low seasons for abortions, e.g. <#/>a few months or weeks following festival seasons or during school holidays when conjugal relations are more likely to occur for those who are restricted at other times. <#/>Ferguson found that most of the pregnancies responsible for drop-outs were conceived during school holidays. <#/>Therefore, studies done around these peak times may lead to a higher incidence, and those done during the low seasons may give low incidence. <#/>The studies covering longer periods may give a relatively more realistic incidence. <#/>All these facts must be taken into account when comparing various study results or referring to a particular one.
<#/>Notwithstanding these shortfalls, the studies have shown that abortion is one of the most common reasons for admission into Kenyan hospitals. <#/>As Mati pointed out, the acute gynaecological ward of Kenyatta National Hospital admits about one-sixth of all admissions to the hospital out of whom an average of 60.0% are due to abortion. <#/>Njuki stresses further that out of the four theatres available at the Nakuru General Hospital, one is reserved wholly for evacuations.
<#/><h> Types of abortion </h>
<#/>Much emphasis has been placed on attempts to categorize abortion as either induced or non-induced (spontaneous), based on various criteria. <#/>This effort reflects the desire to identify the magnitude/proportion of induced abortion, the reasons for termination, characteristics of women concerned, methods used and their outcomes (complications). <#/>The desire for categorization came about as a result of observations made in day-to-day life and in hospital settings: some of the women who have had abortions volunteer a history of interference, while those who deny such a history reveal tell-tale signs suggestive of probable interference and when pressed further sometimes admit to the fact. <#/>Secondly, there is something peculiar about the socio-demographic characteristics, reproductive histories and complications of the women with induced abortion compared with those with non-induced abortion.
<#/>The proportions of induced abortion have been quite variable for several reasons. <#/>Very few women will admit to a history of interference, even when there are obvious signs. <#/>On the other hand, some induced abortions leave no tell-tale indicators so that even to the most experienced doctor, and depending on the presentation of the patient, such a woman may pass unnoticed. <#/>Thirdly, the criteria used are not uniform and are indeed very subjective. <#/>Fourthly, the complications which may compel one to seek medical attention are also quite variable. <#/>Some of the induced may have none at all, whereas some of the non-induced (spontaneous) may have very serious complications and may therefore be labelled otherwise.
<#/>Variations also reflect the criteria used which have included definite history of interference by the woman; finding of foreign bodies in the uterus, vagina or cervix; evidence of sepsis either local or generalized; purulent vaginal discharge; injury to the genitalia; unwantedness of a pregnancy; being single and/or in school/college; or non-contraception at conception of the index pregnancy. <#/>While these may all contribute, they are not invariably causal factors. <#/>An additional cause of variation in the proportion of induced abortion is the differences in the study populations used e.g. the denominators.
<#/>Aggarwal et al. reported that 35.6% of the study group volunteered a history of interference, while a further 26.7% had features suggestive of probable interference such as unwanted pregnancy and sepsis. <#/>Baker and Khasiani based their categorization on history as the women were either known to the interviewers or some of the interviewees. <#/>Lema et al. based their categorization on the patient's history and the attending doctor's opinion which was based on finding foreign bodies in the uterus, genital injuries or social history of the woman such as being a student or a prostitute. <#/>Many relied on the history of the respondents, while others did not specify the criteria used in their studies.
<#/>Based on these criteria, the proportion of induced abortion has varied from 10.7% to 62.5% of all abortions. <#/>Also, there is a lot of variation from one district hospital to another. <#/>Proportions of 62.3%, 28.0% and 17.6% were all noted at the same institution, Kenyatta National Hospital.l
<#/>The experiences of most workers is that induced abortions are more frequent than have hitherto been reported in the literature. <#/>It therefore means that when considering induced abortion as reported in studies, one has to be aware of all these facts and give an allowance for possible under-reporting. <#/>Secondly it perhaps calls for a design of more elaborate criteria which may have less "false-negatives".
<#/>Abortion is regarded as being induced when there has been a deliberate attempt by the woman to terminate the pregnancy either by herself or by another person. <#/>Most workers believe that induced abortions form the majority.
<#/>Induced abortion has existed from far back in history. <#/>It has been used as a method of regulating fertility either in the absence of contraception or as an <-/adjuvant> to it in cases of failure. <#/>For some people and societies around the world it is the only method of fertility regulation, while for others it is used in conjunction with some form of contraception.
<#/>Though previously thought to be the problem of the young single urban "educated" women, studies done in Kenya so far have shown that induced abortion is not limited to them. <#/>All the studies which have been done in the rural communities of Kenya have shown that induced abortion has been and continues to prevail in the rural areas as well. <#/>Apart from the 1989 study by Lema et al., the other hospital-based studies did not specify the residence of the woman at the time of conception of the index pregnancy or of the abortion. <#/>While this may be so, we should not also lose sight of the fact that a good proportion of abortions, especially those among the urban/working class elite, are being done privately and fairly early, as shown by Oyieke, where all the study population had gestational ages of 8 weeks or less, with 87.7% being between 5 and 7 weeks. <#/>This indicates that most of those done privately and early may not have any major complications and may not be on any record.
</I>
<&/>W2A029K

<#/><I> <h> INTRODUCTORY </h>
<#/><h> 1:1 GENERAL INTRODUCTION </h>
<#/>In March 1990, a pest that was causing the drying up of cypress trees was reported in Kiserian area, Ngong Division of Kadiado District. ). <#/>The pest known as the cypress aphid Cinara cupressi Buckton attacks the twigs and branches of host trees resulting in their dieback and drying up of heavily infested trees in Cupressaceae family. <#/>It affects cedar, cypress and callistries trees.
<#/>The cypress aphid is an exotic pest whose natural habitat is in Europe where it feeds on species of Cupressus, Juniperus and Thuga ). <#/>Mills N.J. (1990) reported it as a paleartic species, while the executive (Feb. 1991) reported it as a pest indigenous to the Mediteranean. <#/>It is not well known how or when the pest found its way to Africa. <#/>It has been positively recorded from cypress plantations in the Southern highlands of Tanzania, Burundi and Rwanda where extensive damage has been reported from all plantations of susceptible species
<#/>First reports of the cypress aphids in Africa came from Malawi in 1986 where it is now widespread on Cupressus lusitanica, C. torulosa and Widdringtonia nodiflora. <#/>It was noticed in Rwanda and Burundi in late 1988  <#/>The pest has also been reported in Zaire and Uganda 
<#/>Cedar and cypress trees are very important in Kenya. <#/>They are used mainly for building timber, poles, veneers, plywood, pulp, paper, furniture, woodfuel and charcoal.
<#/>Very little about the cypress aphid is know and extensive research work needs to be done before control can be <-_/implented>. <#/>This should be in the field of lifecycle and reproductive biology, mode of dispersal and migration, epidemiology, fecundity of alatae and apterae, physiological effect on host trees, population dynamics, genetics and its predators and parasitoids among many. <#/>Effect of the abiotic environment on the aphids should also be studied.
<#/><h> 1:2 Statement of the Problem </h><#/>Forests and trees are of varied important benefits to our lives. <#/>They provide benefits such as improving the climate, regulating stream and river flows, conserving and preserving the soil mantel, catchments for lotic and lentic ecosystems, hydrologic cycling, stable habitats for wildlife, nutrients sources as they are primary production ecosystems. <#/>They are also the backbone of many important economic activities of production of paper and industrial timber.
<#/>About 3% of Kenya is reserved forest estate, the bulk (2 million ha) of which supports indigenous forests. <#/>Plantation forests (about 0.15 million ha) provide the bulk of wood demand for domestic and commercial needs. 
<#/>Cypress in Kenya comprises 45 % of the total 168,000 hectares of plantation forest. <#/>Thus some 75,000 hectares of the forest estate is threatened by the cypress aphid 
<#/>Cupressus lusitanica which was introduced into Kenya in 1910 has become an important industrial tree in plantation forests. <#/>It has a relatively high resistance to pests and diseases in Kenya. <#/>From 1952 when C. macrocarpa was dropped as a plantation crop due to its high susceptibility to monochaetia canker, Cupressus lusitanica has remained an important species of the industrial plantation programme. <#/>It currently <-/consitutes> 44 % of the 167,000 hectares of industrial plantations and about 10,000 hectares equivalent dispersed in individual farms as shelter belts, live fences, shade trees etc. <#/>The only known disease of economic importance is armillaria root rot caused by the fungus Armillaria mellea. <#/>This has caused deaths <-/upto> 14 % in some plantations
<#/>Trees in the family Cupressaceae suffer from attacks by insect pests and pathogens just like any other crops. <#/>The cypress aphid is the latest threat to the survival of the trees. <#/>The control of any insect pest demands thorough knowledge of its biology, ecology, fecundity and mode of reproduction, response to changing abiotic environment, dispersal and migration and its susceptibility to natural enemies. <#/>The cypress aphid is largely unknown in this part of the world and even where it originated from as it isn't a serious pest their. <#/>As such there is a great lack of knowledge about its biology and behaviour. <#/>For this reason its biology and behaviour needs to be investigated thoroughly to bring an understanding and hence implement an effective control strategy, chemical, biological, silvicultural or an integration of these.
<#/>It is for this reason that this research project was initiated. <#/>It is hoped that the results will contribute towards an environmentally sound control strategy for this pest.
<#/><h> LITERATURE REVIEW AND OBJECTIVES </h>
<#/><h> 2:1 LITERATURE REVIEW </h>
<#/><h> 2:1:1: The Biology of Aphids </h>
<#/><h> 2:1:1:1 Morphology </h>
<#/>Aphids are an extremely successful group which occurs throughout the world with the greatest number of species in the temperate regions. <#/>Individually they are inconspicuous and small but they can become quite numerous. <#/>Many species are agricultural pests and tree dwelling aphids can severely retard their host plants. <#/>Aphids originated from the Archescytinidae in the carboniferous era, or early permian, 280 million years ago 
<#/>Aphids are small soft bodied insects frequently found in large numbers sucking sap from stems, twigs and leaves of plants hence termed plant lice. <#/>They also affect roots. <#/>A conspiuous evolution of aphids was later associated with the appearance of flowering plants, the angiosperms and the host plants of most present day aphids are angiosperms although some aphids live on gymnosperms and a few species attack ferns and mosses
<#/>They are members of the order Homopotera, Family Aphididae. <#/>They have piercing and sucking mouthparts comprising of four stylets made up of two mandibles enclosing two maxillae. <#/>Within the stylet complex are a salivary channel and a food channel ). <#/>Females and usually also males have functional mouthparts. <#/>All aphids feed on sap. <#/>Most aphids obtain food from the sieve tubes. <#/>pressure of phloem cells to force sap up the very fine food canal in the styles but for aphids feeding on artificial diets they probably use the cibarial pump to suck up their food. 
<#/>Aphids have four wings if alatae. <#/>The forewings are uniform in texture being <-/mebranous> throughout or slightly <-/leatherly>. <#/>The hind wings are always <-/mebranous>. <#/>Forewings are larger than hindwings. <#/>The wings are held rooflike at rest with inner margins overlapping slightly at the apex. <#/>Winged condition is not always observed with some groups having winged and wingless individuals of the same or different sex. ). <#/>Typically there are many structurally different morphs in a species including both sexual and asexual forms. <#/>Polymorphism, which is the development within a species of several different adult forms is characteristic of aphids. <#/>Winged forms can usually be recognized by the venation and relative size of the front and hind wings.
<#/>The winged condition is thought to be more primitive condition in aphids and the apterous condition to have been a later evolutionary development probably through brachypterousness. <#/>Usually, apterae are more fecund than alatae. <#/>Alatae being colonizers are subject to different selection pressures from those acting on apterae. <#/>This may account for alatae producing small offspring and also a larger proportion of their offspring soon after maturation than do apterae As such they can maintain a rapid rate of increase <-/equaling> that of apterae in certain species. <#/>The initial advantage of apterousness was an increase in fecundity because the development and maintenance of wing musculature possibly competes with development of embryos for the limited amount of nitrogen available to the aphid. 
<#/>Aphids are also characterised by a pear-shaped body with a pair of cornicles (siphunculi) at the posterior end of abdomen situated dorsally on the fifth or sixth abdominal segments. <#/>They have fairly long antennae and tarsi are two segmented with two claws. <#/>Aphids are notably relatively inactive 
<#/><h> 2:1:1:2 Reproduction and lifecycles </h>
<#/>The life cycles of many aphids are rather unusual and complex. <#/>Aphids are distinguished from other groups in the Aphidoidea in that the females of at least a few generations do not require fertilization for the development of their embryos and also in that these asexual females are viviparous. <#/>they may possess or lack wings. <#/>Aphids are parthenogenetic and viviparous for most of the year but are also capable of sexual reproduction with the production of fertilized eggs. <#/>The gonads of the female consist of two ovaries, each composed of from 4 to 6 ovaries. <#/>At the distal end of each ovariole is a germarium from which the eggs are ovulated. <#/>In virginoparae eggs begin development without fertilization. <#/>Ovaricles of newly born parthenogenetic females contain embryos. <#/>Thus a mother can have in its ovarioles embryos which in turn have developing embryos, the future grand-daughters. <#/>Embryos or eggs pass to the exterior via an oviduct.
<#/>Aphids appear to show diploid parthenogenesis i.e. no reduction division and development starts from a cell containing a full complement of chromosome including 2x chromosomes. <#/>Males are produced by the loss of an x chromosome at the first division and they produce haploid sperm which contain an x chromosome only.
<#/>Fertilization of haploid eggs of sexual females result in diploid cells with 2x chromosomes thus aphids hatching from fertilized eggs are all females. <#/>Parthenogenesis enables those aphids that survive adverse conditions to produce others like themselves, also capable of surviving in that environment and thus rapidly increase in numbers
<#/>Most species overwinter in egg stage, eggs hatching in spring into females. <#/>Several generations may be reproduced parthenogenetically The first generations usually consist of apterae but later alatae appear. <#/>These may migrate to different host plant and reproductive process continues and later in the season they migrate back to the original host type and a generation of both sexes appears. <#/>This is for aphids that show host alternation. <#/>For aphids with only one host type no migration occurs and different sexes mate, females produce eggs which overwinter 
<#/>Some aphids never produce sexuals and thus no eggs. <#/>They exist parthenogenetically throughout the year and are termed anholocyclic. <#/>Still some host alternating species have both holocyclic and anholocyclic clones 
<#/><h> 2:1:1:3 The Winged Condition </h>
<#/>Winged aphids may be fundatrices, virginoparae, oviparae and males.
<#/>Some factors have been implicated in the development of alate forms. <#/>These are crowding, quality of the host plant, ant attendance, temperature and photoperiod and intrinsic factors. <#/>Crowding seems the most important factor. <#/>The juvenile hormone affects the development of wings and pigmentation during nympal development. <#/>It comes from the corpus allata. <#/>Embryos can also be induced to develop into sexual forms after birth by a hormone produced by neurosecretory cells in the brain. 
<#/><h> 2:1:1:4 Migration and Flight </h>
<#/>Aphids migrate great distances, <-/upto> 1300 <-/kilometers>. <#/>Aphids move from plant to plant most conspicuously by flight. <#/>During the day the air just above the ground is warmest and tends to rise. <#/>Aphids flying during the day are likely to be carried into the upper air by convention currents. <#/>Consequently most flying aphids are at heights in excess of 30 metres. <#/>At sunset, the air above the ground becomes cooler than the air above and convection ceases. <#/>Thus aphids are likely to be carried to high altitudes and brought back to ground level by atmospheric circulation alone. <#/>Atmospheric circulation dominates the aphids' movements because of their low flight speeds, 1.6 to 3.2 km/h relative to the speed of air. <#/>As the air in which aphids fly usually moves faster than 3 km/h the aphids have scarcely any control over where they are going and can be carried for great distances. <#/>They can settle only if they stop flying or if air movement brings them to the ground. 
<#/>Many aphids show bimodal flight periodicity with a peak in numbers in mid-morning and another in the early afternoon. <#/>Number flying each day is governed by number moulting to the adult stage; the length of the teneral period of the adult alate aphid and the weather affecting take off. <#/>Usually tree dwelling aphids fly in very calm conditions. 
<#/>Energy for flight is obtained from respiration of glycogen first then fats. <#/>In fat respiration water is released enabling maintenance of aphid's water content even after prolonged flight. <#/>Aphids do not fly to exhaustion before alighting and they take flight again if they settle on a non-host plant. <#/>On landing, aphids invariably probe the surface and this initial probe, taking less than a minute determines whether an aphid will settle or leave. <#/>However not all aphids settle indiscriminately with regard to plant species. <#/>Aphids taking off for the first time show a strong attraction to short wave light which take them up into the sky, and away from plants. </I>
<#/>W2A030K
<#/><I> <h> INVESTIGATIONS INTO PHLEBOTOMINE SANDFLIES IN THE NAIROBI AREA </h>
<#/>Abstract — Studies were commenced to collect and identify the phlebotomine sandflies found in Nairobi. <#/>These studies were also aimed at determining their numbers as well as assessing the effects of seasonal changes on the sandfly population. <#/>Four trapping methods, namely, light traps, sticky traps, aspiration and human bait were employed. <#/>Eight species and one undescribed species were recorded over a period of 6 months. <#/>The identified species included Phlebotomus guggisbergi (Kirk and Lewis), P. <#/>rodhaini (Parrot), Sergentomyia adleri (Theodor), S. harveyi (Heisch, Guggisberg and Teesdale) and S. bedfordi (Newstead) and an undescribed species. <#/>Most of the sandfly species trapped showed seasonal prevalence. <#/>The seasonal variation was closely related to the weather conditions. <#/>Sandflies were found in termite mounds, animal burrows, caves and dugouts some of which were near human habitations. <#/>Termite mounds and animal burrows were the most preferred habitats.
<#/><h> INTRODUCTION </h>
<#/>Sandflies are haematophagus insects which makes them important medical vectors. <#/>Species of the genera Phlehotomus and Sergentomyia are restricted to the old world, being common in Africa, the Indian subregion and Central Asia. <#/>Lutzomyia species occur in the new world, especially in the forested areas of Central and Southern America.
<#/>Sandflies are known vectors of leishmaniasis caused by different species of the genus Leishmania. <#/>There are over 20 known species of Leishmania of which over a dozen are associated with various forms of leishmaniasis . 
<#/>Clinically, there are two types of leishmaniasis in Kenya, visceral leishmaniasis or kala-azar caused by Leishmania donovani and cutaneous leishmaniasis caused by L. aethiopica, L. major and L.tropica. L. donovani also causes post kala-azar dermal leishmaniasis. <#/>Leishmania major has been isolated only from rodents
<#/>Resting places of sandflies are numerous micro habitats ranging from crevices in tree, to cracks and fissures in the soil. <#/>Different species of sandfly are associated with different habitats <#/>Sandflies show seasonal prevalence and in most cases exhibit a more or less marked seasonal variation in numbers <#/>The objectives of this study were firstly to identify the phlebotomine sandflies found in Nairobi. <#/>Secondly, to assess their abundance and relate the effects of seasonal changes on sandfly population, and thirdly to determine if sandfly species existing in the Nairobi area may be potential vectors of leishmaniasis. <#/>Nairobi is closely situated to the Athi River Plain foci of visceral leishmaniasis.
<#/><h> MATERIAL AND METHODS </h>
<#/><h> Study sites </h>
<#/>Three study sites namely, Langata, Kibera and Roysambu in the Nairobi area were selected. <#/>The sites were identified through a preliminary survey to determine areas where sandflies were abundant and where there were reports by inhabitants of bites by flies other than mosquitoes.
<#/><h> Trapping methods </h>
<#/>The sticky trap method. <#/>Castor oil traps adapted from the devices used by Petrisheva (1935) and Blasova (1932) both cited by Kirk and Lewis (1940) were used. <#/>Transparent polythene sheets
<#/>1 x 1 m and 0.25 mm thick devised by Mutinga (1981), were coated with castor oil on both surfaces and fixed near resting sites of sandflies as described by Mutinga (1981). <#/>These sheets were held by strings in and outside houses, in the forest near tree trunks, caves and near termite mounds.
<#/>The sandflies were expected to be trapped as they flew in and out of their habitats or as they came into houses to feed. <#/>Similar sheets measuring 20 x 30 cm were also used. <#/>These sheets were fixed on forked sticks and inserted into small animal burrows on cracks in the ground. <#/>The sheets were also rolled and placed in the ventilation shafts of termite mounds and sandflies were trapped as they hopped in and out of the shafts. <#/>A total of 30 traps were placed at the sites in the evening at 1830 hr and removed in the morning at 0700 hr, three nights a week for a period of 6 months (November 1989 to April 1990). <#/>The trapped sandflies were then picked from the transparent sheets since they were easily distinguished from other dipterans. <#/>A fine camel hair brush (No. 2) was used to remove the sandflies from the sheet. <#/>The sandflies were then placed in specimen tubes which were well labelled and contained detergent saline.
<#/>The light trap method. <#/>Light traps used were a modification of the Smith and Downes' (1970) CDC light traps consisting of a plexiglass body, a horizontal screen mesh, a torch bulb (three volts), a plastic fan and a removable collecting sandfly net. <#/>The light traps were operated at a height of 1-1.5 m above the ground for three trap nights a week for 3 months (November 1989-December 1989 and January 1990). <#/>Sandflies were sorted out from other dipterans caught in the net the following morning.
<#/>Human bait method . <#/>This method was developed by Kerr (1933). <#/>It is an important method of sampling anthropophilic sandflies and this was the main reason why the method was employed in this study. <#/>An assistant sat on a stool around the termite hills late in the evening from 1830 to 0700 hr in the morning when sandflies were very active. <#/>The assistant exposed his legs and arms. <#/>It was hoped that unfed anthropophilic species would be attracted to the human bait for a blood meal. <#/>This exercise was carried out three times a week for 2 months (March and April 1991).
<#/>Aspiration. <#/>Aspirators used were similar in design to those described by Peffiliev (1968) and Rioux et al. <#/>(1969). <#/>Sandflies were aspirated from crevices in trees, cracks and fissures in soil and other apertures in rocks. <#/>Torches were used to limit the resting flies in their habitats. <#/>Flies caught were blown into a sandfly cage then processed for identification.
<#/><h> Processing the sandflies for mounting </h>
<#/>Sandflies were processed in the conventional way. <#/>They were thoroughly washed in 10% detergent saline to remove castor oil and excess hair using a fine camel hair brush (No.2). <#/>The sandflies were then rinsed in physiological saline and preserved in 70% alcohol in well-labelled specimen tubes. <#/>The mounting procedure used was that of Lewis (1973).
<#/>Identification
<#/>Identification of the sandflies was done using the already developed entomological keys of Kirk and Lewis (1951) and a pictorial key developed by Mutinga (unpubl. for Kenyan sandflies).
<#/><h> RESULTS </h>
<#/><h> Sandfly species recorded </h>
<#/>In total nine species of sandflies were recorded during this study. <#/>The sandflies were collected from various microhabitats in the three sites as shown in Table 1. <#/>The sandfly species varied from one microhabitat to another; P. guggisbergi occurred only in caves and rock crevices, while the unidentified species although predominantly in the ventilation shafts of termite mounds was found resting in animal burrows and dugouts.
<#/>The sandflies also varied in numbers and species composition over the 6 month period, showing seasonal variation. <#/>This could be attributed to varying weather conditions prevailing during a particular month, such as temperature, rainfall and relative humidity from one locality to another (Figs 1a, b, c; 2a, b, c; 3a, b, c).
<#/>The most interesting result during the six month survey was the observation of a previously unidentified Sergentomyia s p., caught in the Roysambu site in February and March 1990 (Fig.4). <#/>This unidentified species also constituted the greatest number of sandflies caught in the three study sites, Roysambu being the site showing the greatest variation in species composition (Table 1). <#/>Only males of this species were caught. <#/>Although these sandflies were found to belong to the sub-genus Neophlebotomus of the genus Sergentomyia, they were found to possess five spines on the style instead of the usual four that occur in this genus. <#/>The male terminalia of this species on the style differed from known male terminalia of this genus in the arrangement of the spines on the style, shape of the penis sheath, paramere and aedeagus shape. <#/>In addition, the cibarial armature and shape of teeth were found to be distinctly different from any of the known species.
<#/><h> DISCUSSION </h>
<#/>There have been reports of minor epidemics of visceral leishmaniasis in the Athi River valley Foci and the isolation of L. major from a naturally infested vervet monkey, Cercoptithecus aethiops from Kiambu district area adjacent to Nairobi District. <#/>It was important to carry out a survey of existing phlebotomine sandflies in Nairobi and to determine their vector potential. <#/>Two genera of sandflies namely, Phlebotomus and Sergentomyia were recorded during this study. <#/>Vector studies in Kenyan foci have shown that termited-welling sandfly species of the genus Phlebotomus, namely two representatives of the Synphlebotomus group, P. vansomerenae and P. martini, are vectors of visceral leishmaniasis and which are cave dwellers, P. Iongipes, P. pedifer,P. elgonensis and P. duboscqi, are vectors of cutaneous leishmaniasis respectively 
<#/>Phlebotomus guggisbergi and P. rodhaini were found in the Nairobi area in the leishmaniasis foci, but P. rodhaini have been caught in small numbers at kala-azar case sites in Baringo District, Rift Valley Province, but they do not bite man. <#/>P. guggisbergi, also occurring in small numbers, have been reported to bite humans in cutaneous leishmaniasis foci in Central Rift Valley Province (Lawyer et al. Unpublished report). <#/>Sergentomyia clydei and S. adleri found in Nairobi, are known to bite humans in kalaazar case sites in Baringo District S. harveyi, S. teesdalei, S. squamipleuris and S. bedfordi found in Nairobi, have also been reported in the Central Rift Valley and Baringo District leishmaniasis foci, but have not been observed to bite man. <#/>The above observations suggest that none of the phlebotomine sandflies in the Nairobi area are likely to be potential vectors of visceral and cutaneous leishmaniasis. 
<#/>The undescribed species which was found to be the most abundant has also been encountered in Machakos District and is under study. <#/>Since only males were caught and they do not require bloodmeals, they do not pose any health hazard to humans. <#/>However, greater efforts need to be made in locating the habitat of the female undescribed species in order to rule out its vector potential.
<#/>The results of this study indicate that termite mounds constitute an important breeding site for sandflies followed by animal burrows in the Nairobi Area. <#/>Similar findings on breeding sites of sandflies have been reported by Heisch et al. <#/>(1956) and Minter (1964). <#/>The observation on seasonal variation in the number of sandflies occurring during the 6-month study period are similar to those reported by Basimike (1988), who reported P. rodhaini, S. bedfordi, S. adleri and S. clydei to be "non seasonal" species. <#/>Wijers and Minter (1962) had earlier reported S. clydei to be a "non seasonal" sandfly.
<#/>This survey clearly confirms the presence of several species of sandflies in Nairobi, some of which could be a biting nuisance to humans, including an undescribed species. 
<#/>Efforts are now being concentrated in locating the microhabitat of females of the species. <#/>Identification of the males caught is being carried out with assistance from the British Museum. 
</I>