Seroepidemiological Studies of Arboviruses in Africa.

The literature on sero-epidemiological studies of flaviviral infections in the African continent is quite scarce. Much of the viral epidemiology studies have been focussing on diseases such as HIV/AIDS because of their sheer magnitude and impact on the lives of people in the various affected countries. Increasingly disease outbreaks caused by arboviruses such as the recent cases of chikungunya virus, dengue virus and yellow fever virus have prompted renewed interest in studying these viruses. International agencies from the US, several EU nations and China are starting to build collaborations to build capacity in many African countries together with established institutions to conduct these studies. The Tofo Advanced Study Week (TASW) was established to bring the best scientists from the world to the tiny seaside town of Praia do Tofo to rub shoulders with African virologists and discuss cutting-edge science and listen to the work of researchers in the field. In 2015 the 1st TASW focussed on Ebola virus. The collections of abstracts from participants at the 2nd TASW which focused on Dengue and Zika virus as well as presentations on other arboviruses are collated in this chapter.

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.

Pyrethroid resistance in Anopheles gambiae s.s. and Anopheles arabiensis in western Kenya: phenotypic, metabolic and target site characterizations of three populations.

Field and laboratory investigations revealed phenotypic, target site and metabolic resistance to permethrin in an Anopheles gambiae s.s. (Diptera: Culicidae) population in Bungoma District, a region in western Kenya in which malaria is endemic and rates of ownership of insecticide-treated bednets are high. The sensitivity of individual An. gambiae s.l. females as indicated in assays using World Health Organization (WHO) test kits demonstrated reduced mortality in response to permethrin, deltamethrin and bendiocarb. Estimated time to knock-down of 50% (KDT50 ) of the test population in Centers for Disease Control (CDC) bottle bioassays was significantly lengthened for the three insecticides compared with that in a susceptible control strain. Anopheles arabiensis from all three sites showed higher mortality to all three insecticides in the WHO susceptibility assays compared with the CDC bottle assays, in which they showed less sensitivity and longer KDT50 than the reference strain for permethrin and deltamethrin. Microplate assays revealed elevated activity of ß-esterases and oxidases, but not glutathione-S-transferase, in An. gambiae s.s. survivors exposed to permethrin in bottle bioassays compared with knocked down and unexposed individuals. No An. arabiensis showed elevated enzyme activity. The 1014S kdr allele was fixed in the Bungoma An. gambiae s.s. population and absent from An. arabiensis, whereas the 1014F kdr allele was absent from all samples of both species. Insecticide resistance could compromise vector control in Bungoma and could spread to other areas as coverage with longlasting insecticide-treated bednets increases.

Application of a reverse dot blot DNA-DNA hydridization method to quantify host-feeding tendencies of two sibling species in the Anopheles gambiae complex.

A DNA-DNA hybridization method, reverse dot blot analysis (RDBA), was used to identify Anopheles gambiae s.s. and Anopheles arabiensis (Diptera: Culicidae) hosts. Of 299 blood-fed and semi-gravid An. gambiae s.l. collected from Kisian, Kenya, 244 individuals were identifiable to species; of these, 69.5% were An. arabiensis and 29.5% were An. gambiae s.s. Host identifications with RDBA were comparable with those of conventional polymerase chain reaction (PCR) followed by direct sequencing of amplicons of the vertebrate mitochondrial cytochrome b gene. Of the 174 amplicon-producing samples used to compare these two methods, 147 were identifiable by direct sequencing and 139 of these were identifiable by RDBA. Anopheles arabiensis bloodmeals were mostly (94.6%) bovine in origin, whereas An. gambiae s.s. fed upon humans more than 91.8% of the time. Tests by RDBA detected that two of 112 An. arabiensis contained blood from more than one host species, whereas PCR and direct sequencing did not. Recent use of insecticide-treated bednets in Kisian is likely to have caused the shift in the dominant vector species from An. gambiae s.s. to An. arabiensis. Reverse dot blot analysis provides an opportunity to study changes in host-feeding by members of the An. gambiae complex in response to the broadening distribution of vector control measures targeting host-selection behaviours.

Bacteremia in Kenyan children presenting with malaria.

Since the etiologies and clinical outcomes of bacteremia in children with Plasmodium falciparum infections, particularly in areas of holoendemic malaria transmission, are largely unexplored, blood cultures and comprehensive clinical, laboratory, hematological, and nutritional parameters for malaria-infected children (aged 1 to 36 months, n = 585 patients) were investigated at a rural hospital in western Kenya. After the exclusion of contaminant microorganisms, the prevalence of bacteremia was 11.7% in the cohort (n = 506), with nontyphoidal Salmonella spp. being the most common isolates (42.4%). Bacteremia was found to occur in a significantly higher proportion of females than males and was associated with elevated blood glucose concentrations and lowered malaria parasite and hemoglobin (Hb) levels compared to those in abacteremic participants. In addition, the incidences of respiratory distress and severe malarial anemia (SMA; Hb level of <6.0 g/dl) were nonsignificantly greater in children with bacteremia. Mortality was 8.5-fold higher in children with bacteremia. Multivariate logistic regression analyses revealed that bacteremia was significantly associated with reduced incidences of high-density parasitemia (HDP; ≥ 10,000/µl) and increased incidences of malnutrition (i.e., underweight; weight-for-age Z score of <-2 using the NCHS system). Since previous studies showed that bacteremia caused by Gram-negative organisms is associated with enhanced anemia and mortality, multivariate logistic regression was also performed separately for randomly age- and gender-matched children with bacteremia caused by Gram-negative organisms (n = 37) and for children found to be abacteremic (n = 74). These results revealed that the presence of bacteremia caused by Gram-negative organisms was significantly associated with reduced HDP, enhanced susceptibility to respiratory distress, SMA (Hb level of <6.0 g/dl), and being underweight (Z score, <-2). Data presented here from a region of holoendemic P. falciparum transmission demonstrate that although bacteremia is associated with reduced malaria parasitemia, a number of unfavorable clinical outcomes, including malnutrition, respiratory distress, anemia, and mortality, are elevated in children with bacteremia, particularly in cases of Gram-negative origin.

In-vivo efficacy of amodiaquine-artesunate in children with uncomplicated Plasmodium falciparum malaria in western Kenya.

OBJECTIVES: To assess the efficacy of amodiaquine-artesunate in an area with high chloroquine resistance in western Kenya. METHODS: Twenty-eight day in-vivo efficacy trial of amodiaquine-artesunate in 103 children aged 6-59 months in western Kenya with smear-confirmed uncomplicated Plasmodium falciparum malaria. RESULTS: The 28-day uncorrected adequate clinical and parasitological response (ACPR) was 69.0%, with 15.5% Late Clinical Failure and 15.5% Late Parasitologic Failure rates. The PCR-corrected 28-day ACPR was 90.2%. Clinical risk factors for recurrent infection (recrudescences and reinfections) were lower axillary temperature at enrollment and low weight-for-age Z-score. The presence of single nucleotide polymorphisms pfcrt 76T and pfmdr1 86Y at baseline was associated with increased risk of recurrent infections, both reinfections and recrudescences. CONCLUSION: Although artemether-lumefantrine (Coartem) is the first line ACT in Kenya, amodiaquine-artesunate is registered as an option for treatment of uncomplicated P. falciparum and remains an effective alternative to Coartem in western Kenya. Continued amodiaquine monotherapy in the private sector may jeopardize the future use of amodiaquine-artesunate as an alternative artemisinin-based combination therapy.

A supervised land cover classification of a western Kenya lowland endemic for human malaria: associations of land cover with larval Anopheles habitats.

BACKGROUND: A supervised land cover classification was developed from very high resolution IKONOS satellite data and extensive ground truth sampling of a ca. 10 sq km malaria-endemic lowland in western Kenya. The classification was then applied to an investigation of distribution of larval Anopheles habitats. The hypothesis was that the distribution and abundance of aquatic habitats of larvae of various species of mosquitoes in the genus Anopheles is associated with identifiable landscape features. RESULTS AND DISCUSSION: The classification resulted in 7 distinguishable land cover types, each with a distinguishable vegetation pattern, was highly accurate (89%, Kappa statistic = 0.86), and had a low rate of omission and commission errors. A total of 1,198 habitats and 19,776 Anopheles larvae of 9 species were quantified in samples from a rainy season, and 184 habitats and 582 larvae from a dry season. Anopheles gambiae s.l. was the dominant species complex (51% of total) and A. arabiensis the dominant species. Agricultural land covers (mature maize fields, newly cultivated fields, and pastured grasslands) were positively associated with presence of larval habitats, and were located relatively close to stream channels; whilst nonagricultural land covers (short shrubs, medium shrubs, tall shrubs, and bare soil around residences) were negatively associated with presence of larval habitats and were more distant from stream channels. Number of larval habitats declined exponentially with distance from streams. IKONOS imagery was not useful in direct detection of larval habitats because they were small and turbid (resembling bare soil), but was useful in localization of them through statistical associations with specific land covers. CONCLUSION: A supervised classification of land cover types in rural, lowland, western Kenya revealed a largely human-modified and fragmented landscape consisting of agricultural and domestic land uses. Within it, larval habitats of Anopheles vectors of human malaria were associated with certain land cover types, of largely agricultural origin, and close to streams. Knowledge of these associations can inform malaria control to gather information on potential larval habitats more efficiently than by field survey and can do so over large areas.

Toxicity of bloodmeals from ivermectin-treated cattle to Anopheles gambiae s.l.

Two anthelmintic drugs used as cattle dewormers, ivermectin and moxidectin, were tested for their lethal and sublethal effects on the malarial vectors Anopheles gambiae s.s. and An. arabiensis. In the laboratory, direct addition of ivermectin to bovine blood reduced the survivorship and fecundity of mosquitoes fed on the blood. The median lethal concentration (LC(50)) of ivermectin in the bloodmeal, for the laboratory populations of An. gambiae s.l., was 19.8 ppb. In the field, commercially available formulations containing ivermectin or moxidectin were injected into cattle at three times the recommended dose. Most (90%) of the An. gambiae s.s. that fed on the ivermectin-treated cattle within 2 weeks of treatment failed to survive more than 10 days post-bloodmeal. No eggs were deposited by An. gambiae s.s. that fed on ivermectin-treated cattle within 10 days of treatment. In contrast, the survivorship and egg production of the mosquitoes that fed on the moxidectin-treated cattle were no different from those feeding on untreated cattle. These results indicate that treatment of cattle with ivermectin could be used, as part of an integrated control programme, to reduce the zoophilic vector populations that contribute to the transmission of the parasites responsible for human malaria.

Daily trimethoprim-sulfamethoxazole prophylaxis rapidly induces corresponding resistance among intestinal Escherichia coli of HIV-infected adults in Kenya.

BACKGROUND: Trimethoprim-sulfamethoxazole (TMP-SMZ) has been recommended by World Health Organization (WHO) as daily prophylaxis for Africans with AIDS to prevent opportunistic infections. Daily TMP-SMZ may reduce its susceptibility to commensal intestinal Escherichia coli (E coli), increasing the burden of TMP-SMZ-resistant pathogens. METHODS: Participants received either daily TMP-SMZ (CD4 <350 cells/mm(3)) or daily multivitamins (MVIs; CD4 > or =350 cells/mm(3)) for 6 months. Stool was collected at baseline, 2 weeks, 2 months, and 6 months. A random E coli was tested for susceptibility. RESULTS: Baseline prevalence of TMP-SMZ resistance ranged from 71% to 81% and was not different across CD4 strata. At 2 weeks, prevalence of TMP-SMZ-resistant E coli increased significantly from 78% to 98% (P < .001) among persons taking daily TMP-SMZ and did not change among persons taking MVIs. CONCLUSIONS: Daily prophylaxis with TMP-SMZ induced in vivo resistance to the drug after 2 weeks. Empiric therapy for diarrhea with agents other than TMP-SMZ should be considered for HIV-infected persons receiving daily TMP-SMZ prophylaxis.

Sporadic paediatric diarrhoeal illness in urban and rural sites in Nyanza Province, Kenya.

OBJECTIVE: Investigate differences in the infectious aetiology, health seeking behaviour, and provider practices with regard to diarrhoeal illness among children presenting to urban versus rural clinics in Western Kenya. DESIGN: Laboratory-based, passive surveillance. SETTING: The urban portion of the study was conducted at the paediatric outpatient clinic of Nyanza Provincial Hospital in Kisumu. The rural portion of the study was conducted at four outpatient clinics in the Asembo Bay community approximately 20 kilometers west of Kisumu. SUBJECTS: Children aged less than five years presenting to medical facilities for the treatment of diarrhoea from October 2001-October 2003 at the urban site and May 1997-April 2003 for the rural sites. RESULTS: Among the 1303 urban and 1247 rural specimens collected, 24% of specimens yielded a bacterial pathogen (24% urban, 25% rural). Campylobacter was the predominant bacterial pathogen (17% urban, 15% rural), followed by Shigella and nontyphoidal Salmonella (both 4% urban and 5% rural). In both communities, susceptibilities of these pathogens to the most commonly prescribed antibiotics was low (< or = 50%); 70% of all episodes of diarrhoea were prescribed antibiotic treatment. Urban health practitioners prescribed fewer antibiotics, chose drugs more likely to be effective, and were more likely to prescribe oral rehydration therapy for bloody diarrhoea. CONCLUSION: Most characteristics of diarrhoeal disease and their causes were similar in paediatric patients presenting to urban and rural clinics. Urban providers were more compliant with WHO recommendations.

Causes of deaths using verbal autopsy among adolescents and adults in rural western Kenya.

OBJECTIVE: To establish causes and patterns of deaths among adolescents and adults (age >11 years) using verbal autopsy (VA) in a rural area of western Kenya where malaria and HIV are common. METHODS: Village reporters reported all deaths in Asembo and Gem (population 135 000), an area under routine demographic surveillance. After an interval of >/=1 month, a trained interviewer used a structured questionnaire to ask the caretaker about signs and symptoms that preceded death. Three clinical officers independently reviewed the interviews and assigned two unranked causes of death; a common cause was designated as the cause of death. RESULTS: In 2003, 1816 deaths were reported from residents; 48% were male and 72% were between 20 and 64 years of age. Most residents (97%) were ill before death, with 60% of illnesses lasting more than 2 months; 87% died at home. Care was sought by 96%; a health facility was the most common source, visited by 73%. For 1759 persons (97%), a common cause of death was designated. Overall, 74% of deaths were attributed to infectious causes. HIV (32%) and tuberculosis (TB) (16%) were the most frequent, followed by malaria, respiratory infections, anaemia and diarrhoeal disease (approximately 6% each). Death in a health facility was associated with young age, higher education, higher SES, a non-infectious disease cause and a shorter duration of illness. CONCLUSION: In this area, the majority of adult and adolescent deaths were attributed to potentially preventable infectious diseases. Deaths in health facilities were not representative of deaths in the community. Programmes to prevent HIV and TB infection and to decrease mortality have started. Their impact can be evaluated against this baseline information.

Sampling outdoor, resting Anopheles gambiae and other mosquitoes (Diptera: Culicidae) in western Kenya with clay pots.

Clay pots were analyzed as devices for sampling the outdoor resting fraction of Anopheles gambiae Giles (Diptera: Culicidae) and other mosquito species in a rural, western Kenya. Clay pots (Anopheles gambiae resting pots, herein AgREPOTs), outdoor pit shelters, indoor pyrethrum spray collections (PSC), and Colombian curtain exit traps were compared in collections done biweekly for nine intervals from April to June 2005 in 20 housing compounds. Of 10,517 mosquitoes sampled, 4,668 An. gambiae s.l. were sampled in total of which 63% were An. gambiae s.s. (46% female) and 37% were An. arabiensis (66% female). The clay pots were useful and practical for sampling both sexes of An. gambiae s.l. Additionally, 617 An. funestus (58% female) and 5,232 Culex spp. (males and females together) were collected. Temporal changes in abundance of An. gambiae s.l. were similarly revealed by all four sampling methods, indicating that the clay pots could be used as devices to quantify variation in mosquito population density. Dispersion patterns of the different species and sexes fit well the negative binomial distribution, indicating that the mosquitoes were aggregated in distribution. Aside from providing a useful sampling tool, the AgREPOT also may be useful as a delivery vehicle for insecticides or pathogens to males and females that enter and rest in them.

Impact of sustained use of insecticide-treated bednets on malaria vector species distribution and culicine mosquitoes.

Insecticide-treated bednets (ITNs) significantly reduce malaria vector populations. Susceptibility to ITNs differs by vector species, and culicine mosquitoes have not been shown to be significantly affected by the use of ITNs. We examined the impact of 2-4 yr of ITN use on malaria vector species distribution and culicine mosquitoes. Routine entomological surveillance was conducted in adjacent areas with and without ITNs from November 1999 to January 2002. Use of ITNs reduced the proportion of Anopheles gambiae Giles relative to Anopheles arabiensis Giles. The number of culicines per house was significantly lower in the ITN area than in the neighboring area. Changes in the An. gambiae sibling species distribution may help to explain apparent mosquito behavioral changes attributed to ITNs. Reductions in culicines by ITNs may have implications for community perceptions of ITN effectiveness and for control of other diseases such as lymphatic filariasis.

Progression of stunting and its predictors among school-aged children in western Kenya.

OBJECTIVE: The objectives of this study were (1) to assess whether a cohort of school-aged children experiences progression of stunting over a 2-y-period of observation and (2) to identify baseline nutritional and body composition risk factors for the progression of stunting. METHODS: As part of a large-scale, randomized controlled trial assessing the impact of insecticide-treated bednets (ITNs) on nutritional status, we longitudinally followed a cohort of school-aged children over a 2-y-period in western Kenya. Anthropometric measurements were made at four time points from which Z-scores for height-for-age (HAZ), weight-for-age (WAZ), and body mass index (BMIZ) were calculated. Two measures of body composition, upper arm fat area and upper arm muscle area, were derived from mid-upper arm circumference (MUAC) and triceps skinfold thickness. RESULTS: Subjects experienced a mean change in HAZ from baseline to 9 months of -0.16 [-0.19, -0.13], from baseline to 16 months of -0.18 [-0.22, -0.15], and from baseline to 24 months of -0.36 [-0.41, -0.31]. Thus, the average individual's change in HAZ at the three follow-up time points is significantly less than zero, meaning that, on average, the cohort is deviating further from NCHS reference medians over time. The baseline nutritional measure that explained the greatest amount of variance in the progression of stunting was the upper arm muscle area Z-score (F=8.1; P=0.005). CONCLUSIONS: This longitudinal study provides further evidence from a distinct ecological setting regarding the progression of undernutrition during middle childhood in the developing world. It suggests that school-aged children in the developing world do not experience catch-up growth or remain stable. Rather, they continue to deviate from NCHS standards, accruing greater height deficits with age. In addition, absolute lean body mass explained the most variability in the progression of stunting, which supports cross-sectional findings from other studies.

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.

Heme peroxidase activity measured in single mosquitoes identifies individuals expressing an elevated oxidase for insecticide resistance.

Optimum conditions are described for a simple, rapid, microplate-based assay that indirectly measures the differences in oxidase levels between individual susceptible, resistant, or induced mosquitoes. A small proportion (0.01-0.1) of a single mosquito is used, allowing multiple replicates of the oxidase assay. Cytochrome C is used as a positive control. The levels of oxidase found in sample populations of pyrethroid-susceptible, pyrethroid-resistant, and phenobarbital-induced Anopheles albimanus mosquitoes are characterized with the assay.

Some emerging issues on the malaria problem in Kenya.

Malaria in Kenya has been characterised by marked variability in its epidemiology, partly reflecting the obstacles and progress made in the control strategies. The impact of anti-vector activities in the 1970s and before have been observed for variable lengths of time afterwards. Malaria has re-emerged in areas previously with little or no transmission. The recovery of infective Anopheles gambiae vector in higher altitudes affirms the potential for transmission in areas where epidemics have been known to occur. Morbidity and mortality patterns in the otherwise endemic lowlands have become increasingly severe, an observation which would be attributed to the increasing inefficacy of chloroquine. Efforts to promote personal protection suffer substantial setbacks in sustainability inspite of apparent acceptability. There are indications that the mosquito vector susceptibility to permethrin and other insecticides will now require continual monitoring in order to detect development of significant resistance. In this communication, we review some emergent issues in malaria transmission in Kenya and the potential for control as adduced from historical and contemporary perspectives.

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.

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.

Maternal immune responses and risk of infant infection with HIV-1 after a short course Zidovudine in a cohort of HIV-1 infected pregnant women in rural Kenya.

OBJECTIVE: To investigate the effects of short-course nucleoside reverse transcriptase inhibitor (Zidovudine, ZDW/AZT) on maternal immune responses and risk of infant infection with HIV-1 among rural-based mothers in western Kenya. DESIGN: A prospective cohort study involving HIV-1 seropositive pregnant mothers and their infants. SUBJECTS: One hundred and seven HIV-1 seropositive asymptomatic pregnant women and their infants. METHODS: After informed consent, the women were enrolled at gestation age between 16-24 weeks. For cultural and economic reasons, all mothers were allowed to breast feed their infants. Short-course antepartum regime of AZT was administered to all mothers starting at 36 weeks gestation until start of labour. Maternal absolute CD4+ T cell subset assays were performed before 3rd trimester (about 36 weeks gestation) and after a 4-week therapy of AZT (at least one month post-nuptially). Infant HIV-1 status was determined by HIV-1 DNA polymerase chain reaction (PCR) on samples sequentially taken at 1, 2, 3, 4, 6 and 9 months and confirmed by serology at 18 months of age. INTERVENTIONS: Antepartum short-course orally administered AZT: 300mg twice-daily starting at 36 weeks gestation until start of labour, 300mg at labour onset and 300mg every three hours during labour until delivery. MAIN OUTCOME MEASURES: Maternal CD4+ T cell counts before and after AZT treatment. Determination of infant HIV-1 infection status. RESULTS: Among 107 women sampled, only 59 received full dose of AZT and thus qualified for present analysis. Of these, 12 infected their children with HIV, while 47 did not. Comparison of CD4+ T cells before and after AZT treatment scored a significant rise in all mothers (P = 0.01). This increase in CD4+ T cells was not significant among mothers who infected their infants with HIV-1 (P = 0.474). However, a significant rise in CD4+ T cells following AZT therapy was observed only in mothers who did not transmit HIV-1 to their infants (P=0.014). CONCLUSION: These data suggest that a rise in the CD4+ T cell counts following short AZT regimen, now widely in use in resource-weak countries, may be evidence of the active suppression of the replication of HIV. However, further studies to examine the multi-factorial effect of CD4+ lymphocytes and pregnancy on MTCT of HIV need to be carried out to help fully explain the effect of AZT on immune response and whether the CD4+T cell count can be used as a true test of immunological normalisation during antiretroviral therapy.