Prevalence and spatial distribution of Trematode cercariae in Vector Snails within different Agro-Ecological Zones in Western Kenya, 2016.

INTRODUCTION: Freshwater vector snails' distribution, infection with cercariae, preferred habitat and possible trematodiases transmission foci is not well known in Western Kenya. We sought to determine the distribution and prevalence of infection of snails per agro-ecological zone and environmental factors in vector snail habitats. METHODS: We conducted a cross-sectional survey from March, 2016 - May, 2016, harvested and identified snails using shell morphology, determined their infection with trematode cercariae using microscopy, used descriptive statistics to estimate the prevalence of infection and relationship between snail abundance and environmental factors. RESULTS: We sampled a total of 1,678 vector snails from 47 sampling sites of which 42% were Lymnaeid, 23% Biomphalaria, 10% Bulinus, 22% Oncomelaniae and 2% Melanoides. Lower Midland I Ago-Ecological Zones had 44% of the snails and streams from springs had 41% of the snails. Overall, 26.5% (445/1678) (95% CI: 24.4 - 28.6) of the snails shed cercariae. Cercariae were found in 11 (23%) of the sites and in all zones. F. gigantica cercariae were shed by L. natalensis, B. pfeifferi, B. sudanica. Lakeshore had both F. gigantica and S. mansoni cercariae shed by B. sudanica. About 72% (1,202/1,678) of snails were found in water with a pH 6.5 - 7.5. Grass habitat had 54% (912/1,678) of the snails. CONCLUSION: Lymnaeid snails were present in all the zones, while streams from springs and near neutral habitats had most of the snails. Infection with trematode cercariae was noted in all the zones. Trematodiases control should be focused on all zones especially in freshwater streams and lakeshores.

Hypertension in sub-Saharan Africa: cross-sectional surveys in four rural and urban communities.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of adult mortality in low-income countries but data on the prevalence of cardiovascular risk factors such as hypertension are scarce, especially in sub-Saharan Africa (SSA). This study aims to assess the prevalence of hypertension and determinants of blood pressure in four SSA populations in rural Nigeria and Kenya, and urban Namibia and Tanzania. METHODS AND FINDINGS: We performed four cross-sectional household surveys in Kwara State, Nigeria; Nandi district, Kenya; Dar es Salaam, Tanzania and Greater Windhoek, Namibia, between 2009-2011. Representative population-based samples were drawn in Nigeria and Namibia. The Kenya and Tanzania study populations consisted of specific target groups. Within a final sample size of 5,500 households, 9,857 non-pregnant adults were eligible for analysis on hypertension. Of those, 7,568 respondents ≥ 18 years were included. The primary outcome measure was the prevalence of hypertension in each of the populations under study. The age-standardized prevalence of hypertension was 19.3% (95%CI:17.3-21.3) in rural Nigeria, 21.4% (19.8-23.0) in rural Kenya, 23.7% (21.3-26.2) in urban Tanzania, and 38.0% (35.9-40.1) in urban Namibia. In individuals with hypertension, the proportion of grade 2 (≥ 160/100 mmHg) or grade 3 hypertension (≥ 180/110 mmHg) ranged from 29.2% (Namibia) to 43.3% (Nigeria). Control of hypertension ranged from 2.6% in Kenya to 17.8% in Namibia. Obesity prevalence (BMI ≥ 30) ranged from 6.1% (Nigeria) to 17.4% (Tanzania) and together with age and gender, BMI independently predicted blood pressure level in all study populations. Diabetes prevalence ranged from 2.1% (Namibia) to 3.7% (Tanzania). CONCLUSION: Hypertension was the most frequently observed risk factor for CVD in both urban and rural communities in SSA and will contribute to the growing burden of CVD in SSA. Low levels of control of hypertension are alarming. Strengthening of health care systems in SSA to contain the emerging epidemic of CVD is urgently needed.