Mapping African animal trypanosomosis risk: the landscape approach.

African animal trypanosomosis (AAT) is a major hindrance to cattle breeding in the Mouhoun River Basin of Burkina Faso. The authors describe a landscape approach that enables the mapping of tsetse densities and AAT risk along the Mouhoun River loop (702 km long) in Burkina Faso. Three epidemiological landscapes were described: the first and most dangerous corresponded to protected forests and their border areas, with a 0.74 apparent density of infectious fly per trap per day (ADTi), the second to a partially disturbed vegetal formation, with a 0.20 ADTi and the third to a completely disturbed landscape with a 0.08 ADTi. Using this risk indicator, the first landscape was 3.92 more risky than the second which was 3.13 more risky than the last. Similar infectious rates were found in all landscapes (approximately 8%) but tsetse apparent densities dropped significantly (p<0.001) in half-disturbed (2.66) and disturbed landscapes (0.80) in comparison to the natural and border landscapes (11.77). Females were significantly younger (mean physiological age of 29 days) only in the most disturbed landscape (p<0.05) than in the two others one (41 days). According to these results, practical implications of stratifying AAT risk and mapping tsetse densities in vector control campaigns are discussed.