Reanalyzing the 1900-1920 sleeping sickness epidemic in Uganda.

Sleeping sickness has long been a major public health problem in Uganda. From 1900 to 1920, more than 250,000 people died in an epidemic that affected the southern part of the country, particularly the Busoga region. The epidemic has traditionally been ascribed to Trypanosoma brucei gambiense, a parasite now confined to central and western Africa. The Busoga region still reports sleeping sickness, although it is caused by T.b. rhodesiense, commonly believed to have spread to Uganda from Zambia in the 1940s. Our analysis of clinical data recorded in the early 1900s shows that the clinical course of sleeping sickness cases during the 1900-1920 epidemic in Uganda was markedly different from T.b. gambiense cases, but similar to T.b. rhodesiense. These findings suggest that T.b. rhodesiense was present in Uganda and contributed to the epidemic. The historic context is reassessed in the light of these data.