Developing a national atlas to support the progressive control of tsetse-transmitted animal trypanosomosis in Kenya.

backgroundAfrican animal trypanosomosis (AAT) is a major livestock disease in Kenya. Even though, over the years various organizations have collected a vast amount of field data on tsetse and AAT in different parts of the country, recent national-level maps are lacking. To address this gap, a national atlas of tsetse and AAT distribution is being developed by the Kenya Tsetse and Trypanosomosis Eradication Council (KENTTEC) and partners.

methodsAll data collected by KENTTEC from 2006 to 2019 were systematically assembled, georeferenced and harmonized. A comprehensive data repository and a spatially-explicit database were created. Input data were collected mainly in the context of control activities, and include both baseline surveys (i.e. pre-intervention) and the subsequent monitoring during and after interventions. Surveys were carried out in four regions (i.e. Western, Rift Valley, Central and Coast), and in 21 of the 47 counties in Kenya. Various devices were used for entomological data collection (i.e. biconical, NGU and H traps, and sticky panels), while the buffy-coat technique was the method used to detect AAT.

resultsTsetse trapping was carried out in approximately 5000 locations, and flies (> 71,000) were caught in all four investigated regions. Six species of Glossina were detected: G. pallidipes (87% of the catches); G. brevipalpis (8%); G. fuscipes fuscipes (4%); G. longipennis (< 1%); G. austeni (< 1%); and G. swynnertoni (< 1%). A total of 49,785 animals (98% of which cattle) were tested for AAT in approximately 500 locations. Of these, 914 animals were found to be infected. AAT was confirmed in all study regions, in particular caused by Trypanosoma vivax (48% of infections) and T. congolense (42%). Fewer cases of T. brucei were found.

conclusionsThe development and regular update of a comprehensive national database of tsetse and AAT is crucial to guide decision making for the progressive control of the disease. This first version of the atlas based on KENTTEC data has achieved a remarkable level of geographical coverage, but temporal and spatial gaps still exist. Other stakeholders at the national and international level will contribute to the initiative, thus improving the completeness of the atlas.