Int. J. Environ. Res. Public Health 2010, 7 1710 taking into account demographic (human, cattle) and ecological factors (Normalized Difference Vegetation Index, land surface temperature) [19]. Still at the scale of the African continent, a recent study defined landscapes that are more or less favorable to tsetse presence/density, showing the role of vegetation and human activities on tsetse distribution [20]. The use of global geospatial data sets for large- and local-scale African trypanosomiasis management is currently being developed [21,22]. In Burkina Faso, the most recent tsetse distribution map available at the country scale was drawn up by Challier and Laveissière [23]. Taking into account the needs of the national PATTEC program in Burkina Faso (Programme de Création de Zones Libérées Durablement de la Tsé-Tsé, PCZLD), together with recent global changes, the aim of this study – jointly undertaken by PCZLD and CIRDES -was therefore to update the northern tsetse distribution limit in Burkina Faso, to compare the results with previous data recorded more than 50 years ago, and to understand the main causes of the changes of this northern limit. In this paper, we will address the three main tsetse species present in the country: two riverine species belonging to the G. palpalis group (G. palpalis gambiensis and G. tachinoides) and one savannah species belonging to the G. morsitans group (G. morsitans submorsitans). 2. Results and Discussion 2.1. Previous Northern Tsetse Limits During the colonial period, Dr. Paul Gouzien (1908) reported the presence of G. morsitans and G. palpalis in the Dori region [24]. This observation was later confirmed by Roubaud et al. [25], who caught tsetse flies (G. palpalis) at the latitudes of Ouahigouya (13°30′N) and Dori (14°N) (Figure 1). In 1949, the Service Géographique de l’Afrique Occidentale Française drew up the results of entomological surveys conducted by the Service Général d’Hygiène Mobile et de Prophylaxie (SGHMP,1944–1949), the organization responsible for the control of SS [26]. The northern limit of tsetse flies was formed by G. tachinoides and is shown in Figure 1. The limit followed a line starting at the latitude of the town of Tougan (13°N) and then joined Kaya at the same latitude. From Kaya, the limit shifted toward Fada N’Gourma at 12°30′N and then shifted toward Sebba (13°30′N). As illustrated, the shift between the northern-most captures of Roubaud et al. [25] (Dori 14°N) and the northern limit of SGHMP in 1949 [26] (Fada N’Gourma, 12°30′N) is roughly 1°30′ to the South (~145 km). The map shows the country of Burkina Faso with its main rivers in blue and protected areas (game parks) in green. It also shows the successive tsetse northern distribution limits in 1935, 1949 and 1977, together with results of trapping obtained in the present work, which allows an update and definition of the current tsetse northern limit in Burkina Faso. This clearly illustrates the north-south shift of this northern limit, which is variable according to longitude, and which now results in the present of two distinct tsetse belts in Burkina Faso. The limit given by Challier and Laveissière in 1977 [23] is also illustrated in Figure 1. In the western part from the Mali–Burkina Faso border to Kaya, the northern tsetse limit did not change between 1949 and 1977 (see Figure 1). However, from Kaya to the east Burkina Faso–Benin border there was a substantial shift toward the south, illustrated by the example of the shift between the latitude of Sebba (13°30′N) in 1949 to Diapaga (12°N) in 1977, equivalent to 1°30′ (~145 km). As can