Association between Rift Valley fever virus seroprevalences in livestock and humans and their respective intra-cluster correlation coefficients, Tana River County, Kenya.

We implemented a cross-sectional study in Tana River County, Kenya, a Rift Valley fever (RVF)-endemic area, to quantify the strength of association between RVF virus (RVFv) seroprevalences in livestock and humans, and their respective intra-cluster correlation coefficients (ICCs). The study involved 1932 livestock from 152 households and 552 humans from 170 households. Serum samples were collected and screened for anti-RVFv immunoglobulin G (IgG) antibodies using inhibition IgG enzyme-linked immunosorbent assay (ELISA). Data collected were analysed using generalised linear mixed effects models, with herd/household and village being fitted as random variables. The overall RVFv seroprevalences in livestock and humans were 25.41% (95% confidence interval (CI) 23.49-27.42%) and 21.20% (17.86-24.85%), respectively. The presence of at least one seropositive animal in a household was associated with an increased odds of exposure in people of 2.23 (95% CI 1.03-4.84). The ICCs associated with RVF virus seroprevalence in livestock were 0.30 (95% CI 0.19-0.44) and 0.22 (95% CI 0.12-0.38) within and between herds, respectively. These findings suggest that there is a greater variability of RVF virus exposure between than within herds. We discuss ways of using these ICC estimates in observational surveys for RVF in endemic areas and postulate that the design of the sentinel herd surveillance should consider patterns of RVF clustering to enhance its effectiveness as an early warning system for RVF epidemics.

Effects of Irrigation and Rainfall on the Population Dynamics of Rift Valley Fever and Other Arbovirus Mosquito Vectors in the Epidemic-Prone Tana River County, Kenya.

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that is found in most regions of sub-Saharan Africa, and it affects humans, livestock, and some wild ungulates. Outbreaks are precipitated by an abundance of mosquito vectors associated with heavy persistent rainfall with flooding. We determined the impact of flood-irrigation farming and the effect of environmental parameters on the ecology and densities of primary and secondary vectors of the RVF virus (RVFV) in an RVF-epidemic hotspot in the Tana River Basin, Kenya. Mosquito sampling was conducted in farms and villages (settlements) in an irrigated and a neighboring nonirrigated site (Murukani). Overall, a significantly higher number of mosquitoes were collected in farms in the irrigation scheme compared with villages in the same area (P < 0.001), or farms (P < 0.001), and villages (P = 0.03) in Murukani. In particular, key primary vectors of RVFV, Aedes mcintoshi Marks and Aedes ochraceous Theobald, were more prevalent in the farms compared with villages in the irrigation scheme (P = 0.001) both during the dry and the wet seasons. Similarly, there was a greater abundance of secondary vectors, particularly Culex univittatus Theobald and Culex pipiens (L.) in the irrigation scheme than in the Murukani area. Rainfall and humidity were positively correlated with mosquito densities, particularly the primary vectors. Adult floodwater mosquitoes and Mansonia spp. were collected indoors; immatures of Ae. mcintoshi and secondary vectors were collected in the irrigation drainage canals, whereas those of Ae. ochraceous and Aedes sudanensis Theobald were missing from these water bodies. In conclusion, irrigation in RVF endemic areas provides conducive resting and breeding conditions for vectors of RVFV and other endemic arboviruses.

Capacity of community-based organisations to disseminate sleeping sickness information.

OBJECTIVE: To assess the capacity of established community based organisations (CBOs) to disseminate information on sleeping sickness control. DESIGN: Participatory interview process administered to randomly selected CBOs in a tsetse and trypanosomosis endemic area. SETTING: Busia district, Western, Kenya. RESULTS: Community based organisations especially women groups and farmer field schools that are internally initiated have the potential to contribute greatly to sustainable sleeping sickness dissemination strategies. The study indicated a mean reach of between 400-600 persons per day, but with a range of up to 1000 persons per day. CONCLUSION: Internally initiated women groups may be the best options for targeting health education programmes with the aim of ensuring sustained community participation.

The treatment pathways followed by cases of human African trypanosomiasis in western Kenya and eastern Uganda.

Although early diagnosis and treatment are key factors in the effective control of human African trypanosomiasis (HAT), many cases of the disease delay taking appropriate action, leading to untold suffering. As a better understanding of treatment-seeking behaviour should help in identifying the obstacles to early diagnosis and effective treatment, the treatment pathways followed by 203 former HAT cases in western Kenya and eastern Uganda have recently been explored. About 86% of the HAT cases had utilized more than two different healthcare options before being correctly diagnosed for HAT, with about 70% each using more than three different health facilities. Only about 8% of the cases reported that they had been correctly diagnosed the first time they sought treatment. Just over half (51%) of the HAT cases had been symptomatic for >2 months before being correctly diagnosed for HAT, and such time lags in diagnosis contributed to 72% of the cases receiving their first appropriate treatment only in the late stage of the disease. The likelihood of a correct diagnosis increased with the time the case had been symptomatic. These observations indicate an urgent need to build the diagnostic capacity of the primary healthcare facilities in the study area, so that all HAT cases can be identified and treated in the early stage of the disease.