The risk of T. b. gambiense infection in Africa. Adapted from. Risk is based on the reported number of gambiense HAT cases in the period 2000-2009 and on Landscan™ human population layers for the same period. As a backdrop, the predicted distribution of the palpalis group of tsetse flies is provided. The palpalis group (Genus: Glossina, subgenus: Nemorhina) includes all the major vector species of gambiense HAT.