Factors associated with strongylida infections in sheep on farms in peri-urban Nairobi, Kenya.

Gastrointestinal parasite infections are among the major limitations to production in sheep in many parts of the world. It is important to continually assess their levels of infection in order to institute control measures and reduce the impact. This study determined the factors associated with the strongylida egg counts in sheep on selected farms in peri-urban Nairobi, Kenya. This was a cross-sectional study in which farm and animal-level data, including faecal samples, were collected from 1640 sheep from 30 purposively selected farms in Ruai, and Kamulu wards in Kasarani sub-county and Utawala and Mihango wards in Embakasi East Sub-County, in Nairobi County Kenya. The faecal samples were subjected to coprological examination using a modified McMaster technique to determine counts of strongylida eggs and coccidia oocysts with a detection level of 100 egg or oocyst per gram (EPG or OPG) of faeces. The positive faecal samples for strongylida eggs were pooled per farm and cultured for morphological identification of larval stage three. Descriptive statistics and multilevel mixed-effect logistic regression analyses were used to determine factors associated with strongylida egg count ≥600 EPG (p < 0.05). The receiver operating characteristics curve was used to assess the overall diagnostic performance in the final model. Strongylida eggs were detected in 45.5% (746/1640) of the sheep, and the mean EPG was 486.0± 858.9 with a median of 200 and a range of 0-16,700. The coccidia oocysts were detected in 49.4% (810/1640) of the sheep with a mean OPG was 341.7± 1782.4, a median of 0 and a range of 0-60,000. In the coprocultures, the nematode genera identified (% differential count of L3) were Haemonchus (90%), Trichostrongylus (5%) and Oesophagostomum (5%). In the final multivariable regression model, the odds of detecting EPG ≥ 600 was 1.44 times higher for sheep shedding coccidia oocysts than those that did not. The odds for detecting EPG ≥ 600 was 4.01 times for sheep in Ruai ward compared with those in the combined Kamulu, Utawala and Mihango wards. The receiver operating characteristic curve area was 73.1%, suggestive of good model performance. The results suggest that gastrointestinal strongylida and coccidia infections are common in sheep and farmers should be educated on the importance of appropriate control measures.

Isolation, Characterization, and Quantification of Bacteria from African Sausages Sold in Nairobi County, Kenya.

African sausages are local popular delicacies in Kenya. Demand for these sausages has resulted in this delicacy's vendors being on the increase. However, health risk posed to unsuspecting consumers of African sausages sold in informal, unhygienic make shift road-side kiosks in major cities of Kenya is largely unknown. A descriptive study was designed to isolate, characterize and quantify bacteria from African sausages sold in Nairobi County. A total of hundred (100) African sausages (62 roasted and 38 nonroasted) were conveniently collected from three meat eatery points of Westlands, Kangemi slum, and Pangani estates. Five genera of bacteria, namely, Staphylococcus spp. at 50.4%, Bacillus spp. at 19.5%, Streptococcus spp. 9.8%, Proteus spp. 2.4%, and E. coli spp. at 1.6%, were isolated from 80 African sausage samples. The total aerobic bacterial count range was between 1.0-9.9x101 and 1.0-9.9x107 log cfu/g with 37 samples having total aerobic bacterial count of between 1.0-9.9 x104 and 1.0-9.9 x107 log cfu/g. There was no significant difference (p>0.05) in distribution of isolates and total aerobic bacterial count across geographical sites studied among the roasted and nonroasted African sausages. This study has demonstrated presence of bacteria in African sausages which are potentially zoonotic to humans. Comprehensive study is needed to sample more eatery meat points in Nairobi and other areas in order to demonstrate pathogenic attributes of these isolates and establish the respective total aerobic bacterial count. There is also need to establish the sources of bacteria due to high total aerobic bacterial count determined in the current study.

Effect of four rounds of annual school-wide mass praziquantel treatment for schistosoma mansoni control on schistosome-specific immune responses.

This study evaluated potential changes in antischistosome immune responses in children from schools that received 4 rounds of annual mass drug administration (MDA) of praziquantel (PZQ). In a repeated cross-sectional study design, 210 schistosome egg-positive children were recruited at baseline from schools in western Kenya (baseline group). Another 251 children of the same age range were recruited from the same schools and diagnosed with schistosome infection by microscopy (post-MDA group). In-vitro schistosome-specific cytokines and plasma antibody levels were measured by ELISA and compared between the 2 groups of children. Schistosome soluble egg antigen (SEA) and soluble worm antigen preparation (SWAP) stimulated higher IL-5 production by egg-negative children in the post-MDA group compared to the baseline group. Similarly, anti-SEA IgE levels were higher in egg-negative children in the post-MDA group compared to the baseline group. Anti-SEA and anti-SWAP IgG4 levels were lower in egg-negative children in the post-MDA group compared to baseline. This resulted in higher anti-SEA IgE/IgG4 ratios for children in the post-MDA group compared to baseline. These post-MDA immunological changes are compatible with the current paradigm that treatment shifts immune responses to higher antischistosome IgE:IgG4 ratios in parallel with a potential increase in resistance to reinfection.

Global phylogenetic relationships, population structure and gene flow estimation of Trialeurodes vaporariorum (Greenhouse whitefly).

Trialeurodes vaporariorum (Westwood, 1856) (Greenhouse whitefly) is an agricultural pest of global importance. It is associated with damage to plants during feeding and subsequent virus transmission. Yet, global phylogenetic relationships, population structure, and estimation of the rates of gene flow within this whitefly species remain largely unexplored. In this study, we obtained and filtered 227 GenBank records of mitochondrial cytochrome c oxidase I (mtCOI) sequences of T. vaporariorum, across various global locations to obtain a final set of 217 GenBank records. We further amplified and sequenced a ~750 bp fragment of mtCOI from an additional 31 samples collected from Kenya in 2014. Based on a total of 248 mtCOI sequences, we identified 16 haplotypes, with extensive overlap across all countries. Population structure analysis did not suggest population differentiation. Phylogenetic analysis indicated the 2014 Kenyan collection of samples clustered with a single sequence from the Netherlands to form a well-supported clade (denoted clade 1a) nested within the total set of sequences (denoted clade 1). Pairwise distances between sequences show greater sequence divergence between clades than within clades. In addition, analysis using migrate-n gave evidence for recent gene flow between the two groups. Overall, we find that T. vaporariorum forms a single large group, with evidence of further diversification consisting primarily of Kenyan sequences and one sequence from the Netherlands forming a well-supported clade.

Prevalence, pathology and risk factors for coccidiosis in domestic rabbits (Oryctolagus cuniculus) in selected regions in Kenya.

BACKGROUND: The potential for rabbit production in Kenya is high. However, high morbidity and mortality of domestic rabbits were reported. OBJECTIVE: The aim of the study was to determine the pathology, prevalence and the predisposing factors to coccidiosis in domestic rabbits in selected regions in Kenya. ANIMALS AND METHODS: A total of 61 farms keeping rabbits in six different counties were visited in the survey. A total of 2680 live rabbits were examined and 61 rabbits and 302 fecal samples were randomly collected from the farms and examined for coccidian oocysts by ante-mortem and post-mortem methods. The predisposing factors to coccidiosis were assessed through questionnaires and direct observation. Chi square (χ(2)) statistics was used with P values < 0.05 considered statistically significant. RESULTS: Of the 302 fecal samples, 85% (P < 0.001) contained coccidian oocysts and 2% harbored nematode eggs (Passalurus ambiguous). The overall prevalence of Eimeria spp. infestation was 85.1% in the study area and 90.2% in the individual rabbits, while prevalence of intestinal coccidiosis and hepatic coccidiosis was 29.5% and 11.5%, respectively. Higher counts of coccidian oocysts per gram of feces were recovered in weaners than in growers and adults rabbits (P < 0.001), rabbits that were kept in high density group housing (P < 0.05) and housing with more than two tiers. CONCLUSION: This study identified group housing of rabbits of different ages and inadequate control of concurrent infections as the major risk factors associated with coccidiosis in domestic rabbits in Kenya.

COMMUNITY PERCEPTIONS OF SCHISTOSOMIASIS TRANSMISSION, PREVALENCE AND CONTROL IN RELATION TO AQUATIC HABITATS IN THE LAKE VICTORIA BASIN OF KENYA.

BACKGROUND: Intestinal schistosomiasis caused by Schistosoma mansoni and urinary schistosomiasis caused by Schistosoma haematobium are widely distributed parasites in several localities of the Lake Victoria basin of Kenya, the former being more prevalent. In Kenya, transmission of the intestinal form of bilharzia (S. mansoni) tends to be closely confined to narrow zones along the shores of large bodies of water such as Lake Victoria where it is endemic and the intermediate host is found. The prevalence of S. mansoni along the Kenyan Lake Victoria basin ranges between 40% and 80%. OBJECTIVE: To assess the community's knowledge and perceptions of schistosomiasis prevalence, transmission and control in relation to aquatic habitats in the Lake Victoria basin of Kenya. DESIGN: Community-based cross-sectional study. SETTING: The Kenyan Lake Victoria basin. SUBJECTS: Two hundred and forty three individuals (both women and men residing in the beaches and surrounding areas) were interviewed about their knowledge and perceptions regarding schistosomiasis. RESULTS: The community regarded schistosomiasis as a naturalistic disease not caused by supernatural forces but by an agent of contamination in water. Knowledge on schistosomiasis transmission and control was low, with 42% of the respondents having no idea on how schistosomiasis is contracted, while 22% and 18% of the respondents mentioned contact with contaminated water and drinking / eating dirty water / food, respectively. Most respondents were familiar with the snails' habitats, but had poor knowledge on aquatic plants harbouring snails, as 57% of the respondents did not know about aquatic plants being associated with schistosomiasis snails. Only 3% of the respondents associated snails with schistosomiasis transmission. Sixty percent (60%) of the respondents mentioned use of tablets and injections as means of treating schistosomiasis, while 38% had no idea how it is treated and 2% mentioned use of local herbs and services of medicine men. CONCLUSION: Majority of Kenyan Lake Victoria basin inhabitants had little awareness about schistosomiasis despite high prevalence of the disease in the region. There is need to adapt prevention and control strategies to the people's livelihoods. There is also need to target the less advantaged members of the community such as women, uneducated and subsistence farmers for intense health education strategies aimed at increasing participation in the control of schistosomiasis. Study to elicit divergence between biomedical and local understandings of schistosomiasis/bilharzia is suggested.

Community perceptions of schistosomiasis transmission, prevalence and control in relation to aquatic habitats in the Lake Victoria Basin of Kenya

Background: Intestinal schistosomiasis caused by Schistosoma mansoni and urinary schistosomiasis caused by Schistosoma haematobium are widely distributed parasites in several localities of the Lake Victoria basin of Kenya; the former being more prevalent. In Kenya; transmission of the intestinal form of bilharzia (S. mansoni) tends to be closely confined to narrow zones along the shores of large bodies of water such as Lake Victoria where it is endemic and the intermediate host is found. The prevalence of S. mansoni along the Kenyan Lake Victoria basin ranges between 40. Objective: To assess the community's knowledge and perceptions of schistosomiasis prevalence; transmission and control in relation to aquatic habitats in the Lake Victoria basin of Kenya. Design: Community-based cross-sectional study. Setting: The Kenyan Lake Victoria basin. Subjects: Two hundred and forty three individuals (both women and men residing in the beaches and surrounding areas) were interviewed about their knowledge and perceptions regarding schistosomiasis. Results: The community regarded schistosomiasis as a naturalistic disease not caused by supernatural forces but by an agent of contamination in water. Knowledge on schistosomiasis transmission and control was low; with 42of the respondents having no idea on how schistosomiasis is contracted; while 22 and 18of the respondents mentioned contact with contaminated water and drinking / eating dirty water / food; respectively. Most respondents were familiar with the snails' habitats; but had poor knowledge on aquatic plants harbouring snails; as 57of the respondents did not know about aquatic plants being associated with schistosomiasis snails. Only 3 of the respondents associated snails with schistosomiasis transmission. Sixty percent (60) of the respondents mentioned use of tablets and injections as means of treating schistosomiasis; while 38 had no idea how it is treated and 2 mentioned use of local herbs and services of medicine men. Conclusion: Majority of Kenyan Lake Victoria basin inhabitants had little awareness about schistosomiasis despite high prevalence of the disease in the region. There is need to adapt prevention and control strategies to the people's livelihoods. There is also need to target the less advantaged members of the community such as women; uneducated and subsistence farmers for intense health education strategies aimed at increasing participation in the control of schistosomiasis. Study to elicit divergence between biomedical and local understandings of schistosomiasis/bilharzia is suggested

You cannot prevent a disease; you only treat diseases when they occur: knowledge, attitudes and practices to water-health in a rural Kenyan community.

OBJECTIVE: Almost 1 billion individuals lack access to improved water supplies, with 2.6 billion lacking adequate sanitation. This leads to the propagation of multiple waterborne diseases. The objective of this study was to explore local knowledge, attitudes and practices to understand the mechanisms and pre-conditions for sustainable uptake and use of these facilities. METHODS: Data collection took place in a rural Kenyan community in September 2009. A qualitative approach was taken, with 4 focus groups and 25 in-depth interviews conducted. Participant characteristics varied by age, gender, education, marital status, employment and community standing. RESULTS: Few participants reported current access to improved water and sanitation facilities. Though they expressed desire for latrines and water sources, barriers including lack of funds and social capital, decrease the ability for installation. Participants understood that there was a link between the quality of water and their health, however, perceived benefits of current contaminated sources outweigh the potential health impacts and proliferate their continued use. CONCLUSION(S): While water-health links are understood to varying degrees within the community, contextual (physical environment), compositional (individual) and collective (community) factors interact to influence health. Community challenges, such as lack of unity, lack of education and lack control were identified as the main barriers to initiating change, despite a desire for increased access to safe water and sanitation.

The prevalence of gastrointestinal helminth infections in pigs in Kenya.

The prevalence of helminth infection, species spectrum and worm burdens in Kenyan pigs was examined. A total of 115 gastrointestinal tracts (GIT) from 61 growers and 54 adult pigs were examined between February 2005 and January 2006. Seventy eight (67.8%) had one or more helminth parasites, of which thirty six (31.3%) were mixed infection. Ten types of helminth parasites encountered in descending order of prevalence were, Oesophagostomum dentatum (39.1%), Trichuris suis (32.2%), Ascaris suum (28.7%), Oesophagostomum quadrispinulatum (14.8%), Trichostrongylus colubriformis (10.4%), Trichostrongylus axei (4.3%), Strongyloides ransomi (4.3%), Hyostrongylus rubidus (1.7%), Ascarops strongylina (1.7%) and Physocephalus sexalutus (0.9%). Oesophagostomum dentatum was the most prevalent species (51.9%) in the adult pigs, while Trichuris suis was the most prevalent species (44.3%) in growers. The highest worm counts were recorded in the out door production system. Oesophagostomum quadrispinulatum, Trichostrongylus colubriformis, Trichostrongylus axei, Hyostrongylus rubidus, Ascarops strongylina and Physocephalus sexalutus were recorded in Kenya for the first time. The high prevalence and wide spectrum observed in the present study suggests that helminth infection may be a constraint to economic pig production in the country and there is need to institute control measures.

Cellular immune responses of schistosomiasis patients are altered by human immunodeficiency virus type 1 coinfection.

In vitro studies suggest that CD4(+) cells with a T helper 2 (Th2) phenotype better support human immunodeficiency virus type 1 (HIV-1) replication than do cells of the Th1 phenotype. As a result, Th2-type immune responses may be substantially affected by HIV-1 coinfection. To test this hypothesis, a comparison was done of proliferation and cytokine production by peripheral blood mononuclear cells from patients with schistosomiasis who were positive or negative for HIV-1. Patients with schistosomiasis with HIV-1 coinfections had significantly lower interleukin (IL)-4 and IL-10 production than did HIV-1-negative individuals. In contrast, interferon-gamma production levels were similar between the 2 groups. Furthermore, in patients with HIV-1, a decrease in CD4(+) T cells was correlated with an increased Th1:Th2 cytokine production ratio. The effect of praziquantel treatment on proliferation and cytokine responses also differed between HIV-1 infection groups. Thus, HIV-1 infection affects immune response patterns of patients with schistosomiasis.

Progressive atrophic rhinitis in a medium-scale pig farm in Kiambu, Kenya.

Forty-two pigs in a herd of 117 displayed various clinical signs of progressive atrophic rhinitis. The main signs included sneezing, coughing, lachrymation, serous to mucopurulent nasal discharge, and nasal bleeding in 1 pig. Three pigs had lateral deviation of the snout, while 4 had brachygnathia superior with obvious deformation of the face. Four acutely affected weaner pigs appeared weak, while the 7 chronically-affected pigs appeared smaller than their apparently unaffected penmates of the same age. Treatment of the acutely affected pigs with long-acting oxytetracycline at 20 mg/kg body weight intramuscularly, repeated once after 7 days, reduced the severity but did not clear the sneezing from all the pigs. Fifteen pigs were slaughtered 2 months after the clinical diagnosis was made. The carcasses of the chronically affected pigs were about 15% lighter than those of the apparently normal pigs of the same age and from the same pen, which translated to a loss of 921.00 Kenya shillings per pig (US$13.7). Diagnosis of progressive atrophic rhinitis was confirmed by sectioning the snouts of randomly selected slaughtered pigs with obvious deformation of the snout. Sections were made at the level of the 1st/2nd upper premolar tooth. Varying degrees of turbinate atrophy, from mild to complete, were noted. Histopathology of the turbinates revealed metaplasia of nasal epithelium and fibrosis in the lamina propria.

The effect of treatment of schistosomiasis on blood plasma HIV-1 RNA concentration in coinfected individuals.

OBJECTIVE: To determine whether drug treatment of Schistosomiasis mansoni infection leads to a reduction in plasma HIV-1 RNA concentration in coinfected individuals. METHODS: Stool and plasma samples were obtained prospectively from a cohort of HIV-infected persons (n = 30) in Kisumu, Kenya, before and after treatment of schistosomiasis with praziquantel (mean follow-up, 5.6 months; range 1-15 months). Schistosomal circulating cathodic antigen (CCA) concentrations in plasma were determined by ELISA and fecal egg counts were determined by microscopy. HIV-1 RNA concentrations were measured in pre- and post-treatment plasma samples obtained from the patients whose stool samples remained free of schistosomal eggs for the great majority of the follow-up period. RESULTS: Comparison of pretreatment and follow-up samples revealed that mean +/- SD fecal egg burden was reduced by 96.7% (481.5+/-803.5 versus 16.1+/-24.4 eggs/g feces) and mean plasma CCA concentration decreased by 90.1% (3.22+/-3.26 versus 0.32+/-0.38 microg/ml). In contrast, mean plasma HIV-1 load increased from 3.60+/-0.90 to 3.93+/-0.95 log10 RNA copies/ml (P< 0.001). Although no correlation was found between changes in HIV-1 load and changes in schistosomal burden, there was a significant correlation between changes in plasma HIV load and the time interval between pretreatment and follow-up samples (r = 0.41; P = 0.027). CONCLUSIONS: Treatment of schistosomiasis was not associated with a reduction in plasma HIV-1 load. This study does not, however, exclude the possibility of an adverse effect of helminthic infections on HIV-1 pathogenesis.

Knowledge and attitudes to malaria control and acceptability of permethrin impregnated sisal curtains.

OBJECTIVES: The objectives of this study were to conduct a survey on the knowledge and practices relating to malaria prevention and treatment in two rural communities in Western Kenya, and to determine the acceptability of specially designed permethrin impregnated sisal strands curtains previously introduced into one of the study communities as barriers to mosquito biting. DESIGN: A knowledge, attitudes and practices (KAP) survey was conducted by pre-trained interviewers using a pre-tested questionnaire. SETTING: The study was conducted in two communities located 15 km northwest of Kisumu town, and next to the swamps bordering Lake Victoria in Kisumu District, Western Kenya. PARTICIPANTS: Adult individuals from 50 houses selected from the intervention, and 50 houses from the control sites were included in the study. RESULTS: Both communities had a clear conception of malaria and its symptoms, and of the mosquito as its vector. Malaria was recognised as a potential cause of death by 44% and 72% of the participants in the intervention and control sites respectively. Sixty two per cent to 74% of the people interviewed in both sites named mosquitoes as the causative agents of malaria. Chloroquine was still the drug of choice for malaria treatment, with over 70% usage among the study population. Mention of pyrimethamine/sulfadoxine and pyrimethamine/sulfalene as alternative therapy was below five per cent. Despite a high level (86%) of awareness of bednets as effective barriers to mosquito biting, they were reported in use by less than 35% in both communities. Sisal strand curtains were considered effective and acceptable to more than 80% of the community. CONCLUSIONS: The results of this study underscore the existing need for affordable means of mosquito control, such as sisal strand curtains, for such rural communities which may be acutely aware of the problems associated with malaria, but are constrained from taking any action by lack of resources.

Studies on schistosomiasis in western Kenya: II. Efficacy of praziquantel for treatment of schistosomiasis in persons coinfected with human immunodeficiency virus-1.

Praziquantel is the drug of choice for schistosomiasis chemotherapy. Although the exact mechanism of how praziquantel kills schistosomes remains poorly understood, the immune response of the host is an important factor in drug efficacy. It is thus possible that disease states of humans that lead to immunodeficiencies, such as infection with human immunodeficiency virus-1 (HIV-1), may render praziquantel less effective in treating schistosomiasis. To test this hypothesis, persons with high levels of Schistosoma mansoni infection who were or were not also infected with HIV-1 were treated with a standard regimen of praziquantel and monitored by quantitative fecal examination and plasma circulating cathodic antigen. Both groups responded to praziquantel therapy equally and individuals with low percentages (< 20%) of CD4+ T cells did not differ from individuals with higher CD4 cell percentages. These data demonstrate that persons with HIV-1 infection can be treated effectively for schistosomiasis with praziquantel.

Studies on schistosomiasis in western Kenya: I. Evidence for immune-facilitated excretion of schistosome eggs from patients with Schistosoma mansoni and human immunodeficiency virus coinfections.

Persons employed as vehicle washers in the town of Kisumu, Kenya are exposed for several hours each day to water in Lake Victoria that contains Schistosoma mansoni-infected Biomphalaria pherifferi snails. This results in a focus of high endemicity for schistosomiasis and these persons have very high concentrations of eggs in their feces (mean +/- SD = 1,469 +/- 1,581 eggs per gram [EPG] of feces). Fecal egg counts, but not circulating cathodic antigen (CCA) levels, in these schistosomiasis patients differed strikingly based on the patient's seropositivity for human immunodeficiency virus (HIV). Patients who were infected with S. mansoni and were seropositive for HIV had similar levels of CCA but excreted fewer eggs (643 +/- 622 EPG; n = 16) than individuals who were not seropositive for HIV infection (1,891 +/- 1,779 EPG; n = 37) (P = 0.009). Egg excretion ratios (EPG/CCA) of the seronegative group were also significantly higher than those of the seropositive group. Those in the seropositive group showed a significant correlative relationship between egg excretion ratios and CD4+ lymphocyte percentages. These observations are compatible with the hypothesis that schistosome eggs exit the human host through the requisite facilitation of functional immune responses, and that the efficacy of this process decreases in schistosomiasis patients co-infected with HIV as their peripheral blood CD4- cell levels decrease.

Field trial of permethrin impregnated sisal curtains in malaria control in western Kenya.

A trial to determine the effectiveness of sisal eaves-curtains impregnated with permethrin for malaria control was conducted in the malaria holoendemic western Kenya between 1991 and 1993. Indoor resting densities of Anopheles gambiae s.l. and Anopheles funestus were reduced by 90.9% and 93.8% respectively in protected houses. The entomological inoculation rate (EIR) was reduced by 72% in the intervention village. There was no significant reduction in vector longevity or survival as shown by the sustained high sporozoite rates. Monthly bioassays for retained insecticidal potency of permethrin on the fibre indicated vector mortality rates above 95% over the period. Of 283 and 240 children followed up from the intervention and control villages, a mean malaria prevalence of 43.2% and 52.2% respectively was observed over the trial period (p < 0.01). The prevalence rose to 73.5% and 75.7% (p = 0.541) respectively after the removal of the curtains. No significant differences were observed in the mean parasite density between the groups or between the proportions with parasite density exceeding 2,500 per microliter and with or without fever. The prevalence of splenomegaly was significantly lower in the intervention group compared to the control, both during (p = 0.005) and after the intervention (p < 0.001). There was no significant difference in the mean change in haematocrit at the end of the intervention. We observe that permethrin impregnated sisal curtains effectively retain permethrin, alter favourably the indoor vector density and EIR, and could provide a reduction in malaria prevalence.

Some observations on the biting behavior of Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus and their implications for malaria control.

Studies were carried out in three villages in western Kenya on the biting behavior of Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus. Blood feeding behavior and departure from houses were studied under the impact of permethrin-impregnated eaves-sisal curtains. Only 2-13% of the female vector population was collected biting before 2200 hr. Over 90% of the villagers went to bed by 2100 hr. An. funestus was 6.6-8.2 times more likely to bite people indoors than outdoors, while An. gambiae s.l. females were only 2 times as likely. Under the influence of permethrin-impregnated sisal curtains placed under the eaves of village houses, there was a marked egress of blood-fed An. funestus and An. gambiae s.s. Permethrin seems to have induced exophily of half-gravid female An. gambiae s.s. While An. gambiae s.s. remained highly anthropophagic under the impact of permethrin, An. funestus shifted to feeding more on cattle. An arabiensis were largely zoophilic. Our results underline the difficulties of controlling An. gambiae s.s., the principal African malaria vector. New strategies must be found to control this vector.

Donkey klossiellosis in Kenya.

Out of eight donkeys examined, two had gametogonic and sporogonic stages of Klossiella equi in their kidneys. Gametogonic stages included microgametocytes and macrogametocytes, some of them in syzygy. They were found in enlarged parasitophorous vacuoles situated in epithelial cells of the renal tubules. Sporonts were seen in the epithelial cells protruding into the tubular lumen while sporoblasts, sporocysts and sporozoites were found freely in the tubular lumen. Entire sporocysts were rarely encountered but sporozoites liberated from the ruptured sporocysts could be seen. No inflammatory reaction could be attributed to the presence of these parasites.

Small-scale field evaluation of the monomolecular surface film 'Arosurf MSF' against Anopheles arabiensis Patton.

A field trial was conducted to test the insecticidal action of the monolayer surface film 'Arosurf MSF' applied by knapsack sprayers, against larvae and pupae of Anopheles arabiensis Patton in a rice irrigation scheme in Western Kenya. Larval and pupal densities and the number of emerging adults were determined by dipping and emergence cages respectively. Application of the monolayer by knapsack sprayers provided good coverage. There were high daily mortalities of the fourth instar larvae, with no adult emergence from 'Arosurf MSF' treated plots compared to lower fourth instar mortalities and continuous adult emergence from untreated control plots, indicating the potential of the monolayer for control of An. arabiensis mosquitoes in rice fields.