Rickettsia felis in Aedes albopictus Mosquitoes, Libreville, Gabon

HAT data indicate seasonality of this disease; incidence is higher during January, February, and March (p = 0.04, by Mann-Whitney test). Seasonality of HAT incidence has been noted elsewhere and linked to seasonal infl uences on tsetse habitat suitability. We propose that seasonality of cattle trading may also play a role because cattle purchases increase before the Christmas season, which promote pathogen spread and increased transmission. This fi nding is consistent with research highlighting the role of livestock markets in the spread of T. b. rhodesiense in central Uganda and would further support a body of literature suggesting, as espoused by the SOS initiative, that control of animal reservoirs of the disease is a critical component of intervention measures (2,7–9). Implementation and enforcement of regulations for treatment of cattle before sale at markets would also contribute to limiting spread (9,10); Interventions in districts in central Uganda in which convergence is predicted have been slow and incomplete. If convergence has occurred, this fi nding indicates that a specifi c region in Africa has had concurrent infection with both causes of HAT, with implications for prevention, treatment, and control. Since 2000, Uganda has had continued northward spread of T. b. rhodesiense infections, reducing the distance with TbG to <100 km, which we believe is a conservative estimate. Reinstatement of active surveillance of HAT and support for central data collection in Uganda are long overdo and warranted immediately.