BackgroundAfter a long period of neglect, initiatives are being implemented in Sudan to control tsetse and trypanosomosis. Their planning, execution and monitoring require reliable information on the geographic distribution of the disease and its vectors. However, geo-referenced and harmonized data at the national level are lacking, despite the fact that a number of epidemiological studies were conducted over the years. The Atlas of tsetse and bovine trypanosomosis in Sudan tries to fill this gap.MethodsThe present study includes both a review of historical datasets on tsetse flies and bovine trypanosomosis, as well as the results of recent, targeted field investigations. The review includes both published and unpublished datasets collected in Sudan from 1960 onwards. Targeted field investigations were conducted for trypanosomosis in Blue Nile (2011) and Gezeira States (2012), for tsetse flies in South Darfur (2012) and Blue Nile States (2009 and 2011), and for other trypanosomosis vectors in seven States (Khartoum, Gezeira, White Nile, Blue Nile, North Kordofan, Kassala and Gadarif). The latter surveys, conducted from 2010 to 2012, also enabled us to confirm the absence of tsetse flies in a number of locations.ResultsTsetse fly infestation in Sudan appears to be limited to two relatively small areas at the south-western and south-eastern tips of the Country (South Darfur and Blue Nile State respectively). Glossina morsitans submorsitans is present in both areas, whilst G. fuscipes fuscipes is found only in the latter. In contrast, bovine trypanosomosis is widespread, its presence having being confirmed in eleven States and suspected in all the others. Both mechanical transmission by non-cyclical vectors and animal movement contribute to this broad distribution of trypanosomosis. This is especially the case for Trypanosoma vivax, which was found even in sedentary cattle at hundreds of kilometres of the tsetse belt.ConclusionsThe Atlas provides a spatially-explicit synthesis of the current knowledge of tsetse and bovine trypanosomosis in Sudan. Its various epidemiological outputs are being used to target both trypanosomosis control activities and further data collection exercises. Activities are ongoing to expand the Atlas to non-cyclical vectors and hosts other than cattle.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1485-6) contains supplementary material, which is available to authorized users.

Atsetse survey of Southern Darfur province, Sudan showed that the distribution of the only species present, Glossina morsitans submorsitans, had not appreciably altered over 10 years. Fly populations are most dense south of the Wadi Umbelasha but light infestations are found in the woodlands north of this riverine system to a latitude of about 10 degrees 15' N. Data are given on host availability which is thought to be the major factor determining tsetse distribution. The relative importance of tsetse and of tabanids as transmitters of bovine trypanosomiasis in the province is discussed. The evidence indicates that tsetse are very much more important and that cattle are most at risk of contracting infections during their dry season southerly migrations to the tsetse belts especially during their "Rushash" migration at first rains. Possibilities of tsetse control are discussed but in the short term trypanosomiasis control is most likely best achieved by chemical prophylaxis/therapy of cattle at risk.

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