An atlas to support the progressive control of tsetse-transmitted animal trypanosomosis in Burkina Faso

Abstract

Background African animal trypanosomosis (AAT), transmitted by tsetse flies, is arguably the main disease constraint to integrated crop-livestock agriculture in sub-Saharan Africa, and African heads of state and governments adopted a resolution to rid the continent of this scourge. In order to sustainably reduce or eliminate the burden of AAT, a progressive and evidence-based approach is needed, which must hinge on harmonized, spatially explicit information on the occurrence of AAT and its vectors. Methods A digital repository was assembled, containing tsetse and AAT data collected in Burkina Faso between 1990 and 2019. Data were collected either in the framework of control activities or for research purposes. Data were systematically verified, harmonized, georeferenced and integrated into a database (PostgreSQL). Entomological data on tsetse were mapped at the level of individual monitoring traps. When this was not possible, mapping was done at the level of site or location. Epidemiological data on AAT were mapped at the level of location or village. Results Entomological data showed the presence of four tsetse species in Burkina Faso. Glossina tachinoides, present from the eastern to the western part of the country, was the most widespread and abundant species (56.35% of the catches). Glossina palpalis gambiensis was the second most abundant species (35.56%), and it was mainly found in the west. Glossina morsitans submorsitans was found at lower densities (6.51%), with a patchy distribution in the southern parts of the country. A single cluster of G. medicorum was detected (less than 0.25%), located in the south-west. Unidentified tsetse flies accounted for 1.33%. For the AAT component, data for 54,948 animal blood samples were assembled from 218 geographic locations. The samples were tested with a variety of diagnostic methods. AAT was found in all surveyed departments, including the tsetse-free areas in the north. Trypanosoma vivax and T. congolense infections were the dominant ones, with a prevalence of 5.19 ± 18.97% and 6.11 ± 21.56%, respectively. Trypanosoma brucei infections were detected at a much lower rate (0.00 ± 0.10%). Conclusions The atlas provides a synoptic view of the available information on tsetse and AAT distribution in Burkina Faso. Data are very scanty for most of the tsetse-free areas in the northern part of the country. Despite this limitation, this study generated a robust tool for targeting future surveillance and control activities. The development of the atlas also strengthened the collaboration between the different institutions involved in tsetse and AAT research and control in Burkina Faso, which will be crucial for future updates and the sustainability of the initiative. Graphical Abstract

The national atlas of tsetse flies and African animal trypanosomosis in Ethiopia

“…By contrast, T. vivax was relatively more prevalent in Kenya (ratio 1.14). As to T. brucei, its very low prevalence in Ethiopia is similar to the very low levels found in other countries [22,46,47,49].…”

“…When compared with large-scale investigations of similar size, scope and diagnostic method, the observed prevalence for bovine trypanosomosis in western Ethiopia is shown to be higher than in tsetse-infested areas in Kenya (1.8% [ 47 ]), but lower than in Burkina Faso (6% [ 49 ]) and Mali (7% [ 46 ]). It is also lower than Nigeria, where a literature review yielded an 8.6% prevalence [ 22 ].…”

“…National atlases previously developed in other countries (i.e. Sudan, Mali, Kenya, Zimbabwe and Burkina Faso) also provided additional methodological references [21,[46][47][48][49].…”

“…The time coverage of 10 years is arguably another limitation of this first edition of the atlas. In fact, other existing national atlases cover periods of 15-20 years or more [21,[46][47][48][49]. A time frame longer than 10 years would allow temporal trends to be better captured [48], and it would also help fill some of the existing geographical gaps.…”

Molecular epidemiology of Animal African Trypanosomosis in southwest Burkina Faso

“…The result is a better knowledge of African animal trypanosomosis in this part of the country. The study also provides data that will be included in the national atlas of tsetse and AT in Burkina Faso, thus allowing to enhance and update it [49,50]. The spread of T. vivax at the expense of T. congolense, the likely low-level presence of T.b.…”