Although the parasite causing human African trypanosomiasis was only identified in 1901, 'sleeping sickness' is thought to have existed on the African continent for centuries.
Intensive research over the following decades provided important knowledge about the disease's epidemiology. Despite the numerous epidemics which broke out during the early half of the twentieth century, the high commitment of health authorities to control the disease allowed to bring it close to elimination by the 1960s.
However, after achieving independence during the 1960s, the health system in most endemic countries broke down and control programmes were abandoned or weakened by other priorities. This caused a dramatic reappearance of human African trypanosomiasis in the late 1980s, with some villages reporting levels as high as 50% of the entire village population.
In 2001, WHO launched a major initiative to reinforce disease control and surveillance.
During the last ten years, the number of new cases of HAT reported to WHO has shown a clear decrease, either in the Gambiense form as well as in the Rhodesiense form. For the first time in more than 50 years, the number of reported cases dropped below 10,000 cases per year: 9878 new cases were reported in 2009 and 7139 in 2010. The decrease of cases reported during the period 2001-2010 has been 73,4%. This reduction does not reflect a lack of control efforts as active testing has been maintained between 3 million and 2 million and a half people screened by year and the number of health centres and hospitals participating in the passive screening has increased.
In February 2008, WHO launched the initiative of the Atlas of HAT to map at village level all reported cases during the period 2000–2009. This initiative is jointly implemented with FAO within the PAAT framework. The process is ongoing and includes the 25 countries having reported at least one case in the last ten years. The Atlas is built from a database including geographical and not published epidemiological data), compiled by WHO through the contribution of SSNCPs, NGOs and Research Institutes.
Based on information on the HAT reported cases and the geographic distribution of human population, spatially explicit estimates of population at risk have been calculated and classified in five categories of risk, ranging from “very high” to “very low”. Approximately 70 million people are estimated to be at different levels of risk of contracting HAT in Africa.