Human African trypanosomiasis

Published on January 31, 2021   31 min

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Hello, I'm Sue Welburn, I'm a professor of medical and veterinary molecular epidemiology at the University of Edinburgh. My work over the last three decades has sought to improve the diagnosis and surveillance of infectious diseases in resource-poor settings in Africa and Southeast Asia. My major area of specialism is human African sleeping sickness, also known as human African trypanosomiasis, and my major interest is developing innovative methods for control of these diseases.
Human African trypanosomiasis (HAT, or sleeping sickness) affects neglected populations across 36 countries in sub-Saharan Africa. The disease is caused by infection with a hemoflagellate parasite that invades the blood and lymph glands, and subsequently the central nervous system, where infection leads to profound behavioural changes, convulsions, or altered mental state. It gets its name 'sleeping sickness' because people experience sleep disturbances; they're overcome by sleep during the day and they can be very wakeful at night. Approximately 70 million people distributed over a surface of 1.55 million kilometres squared are estimated to be at different levels of risk of contracting HAT. An estimated 21 million people are at moderate-to-high risk of exposure in around 200 separate active HAT foci, where more than one case per 10,000 inhabitants per year is reported. The disease is estimated to cause 1.6 million DALYs. HAT exists in two distinct forms within these distinct geographical foci: Trypanosoma brucei rhodesiense HAT, which presents as an acute infection; and Trypanosoma gambiense HAT, which presents as a chronic infection.
Between 300,000 and 500,000 people are estimated to be affected by HAT, with 30,000 new cases per year, and over 80 percent of these cases are of the T. b. gambiense form of HAT (the chronic form). Without treatment, HAT is considered always fatal and treatment is both expensive and complex to administer. The disease can be transmitted by the bite of an infected tsetse fly, vertically by maternal transmission, or through sexual transmission. As I said, treatments are complex and expensive to administer, at over $120 per person. HAT is subject to very high levels of under-reporting, it's been estimated that for every person receiving treatment, another 12 die unreported.