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

Abstract

Background: African 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. Methods: All 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. Results: Tsetse 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. Conclusions: The 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 KENT-TEC 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.

Tsetse blood-meal sources, endosymbionts and trypanosome-associations in the Maasai Mara National Reserve, a wildlife-human-livestock interface

“…swynnertoni was less abundant. This finding corroborates previous studies in which these two savannah tsetse species were found to be predominant in the Maasai Mara-Serengeti ecosystem of Kenya and Tanzania [ 5 , 53 ]. As both species are competent vectors of human and animal trypanosomes [ 52 , 54 , 55 ], their presence highlights the persistent risk of AAT and HAT in the MMNR.…”

“…African trypanosomiasis is endemic in regions inhabited by the insect vector in 37 countries in Africa, rendering approximately 70 million people and 60 million cattle in AT-endemic regions are at risk of infection [1,2]. Consequently, reduced productivity due to chronic disease in humans and animals and loss of livestock through death threatens food security, quality of living, and economic stability, particularly in regions where pastoralism is the main economic activity [3][4][5]. Therefore, more effective AT control and management strategies are required.…”

An atlas of tsetse and animal African trypanosomiasis in Zimbabwe

“…The goal of assembling, harmonizing and geo-referencing tsetse and AAT data collected by the TCD and DVFS for the period 2000-2019 has been achieved. This national atlas for Zimbabwe follows the ones for Sudan [12], Mali [22] and Kenya [23], but vastly exceeds them in terms of the number of data points. In particular, the overall trapping effort in Zimbabwe is approximately 1 million trap days, compared to < 20,000 trap days in other countries.…”

“…However, a unified, centralized and regularly updated database was never developed, thus hampering evidence-based decisionmaking. Against this backdrop, the FAO continental atlas of tsetse and AAT [13,20,21] provided the blueprint to develop a national atlas in Zimbabwe and in other countries [12,22,23]. The development of national atlases was also spurred by the need to inform the progressive control pathway (PCP) for AAT [6].…”

An update on the distribution of Glossina (tsetse flies) at the wildlife-human-livestock interface of Akagera National Park, Rwanda

“…Tsetse habitat in the eastern region of Rwanda has reduced greatly due to the demographic pressure. The remaining savannah habitat seems to favour G. pallidipes, which tends to dominate other savannah species in the region (Ciosi, Masiga, and Turner 2014; Saarman et al 2019) ; [52]. The high tsetse abundance in Akagera NP was found all year round with seasonal variations from wet to dry season.…”