Sleeping Sickness in Liberia – A Historical Review

Sleeping sickness or Human African Trypanosomiasis (HAT) caused by Trypanosoma brucei gambiense is a vector-borne protozoan disease occurring in central and western Africa. HAT caused devastating epidemics during the last century. Due to sustained efforts of surveillance and control measures the disease incidence dropped dramatically during recent years. HAT is now targeted for elimination for the year 2020. The epidemiological significance of ancient HAT foci not being surveyed or the non-provision of data recording for long periods, due to war riots and civil unrest like in Liberia is not clear. Its assessment, however, is essential for the implementation of future control strategies. The review compiles the history of the HAT of Liberia with results of known but partly unpublished details of active and passive surveillance of ancient HAT foci (Lofa and Bong Counties). Forty-three HAT cases mainly of Bong County are listed for the years 1967 to 1989; no cases were diagnosed in the ancient Kissi focus. An experimentally prooven antelope-Glossina palpalis gambiensis- antelope cycle of T. b. gambiense emphasizes the epidemiological role of animal reservoir hosts in the Liberian rainforest with implication for the resurgence of the disease.