What is African Sleeping Sickness?

made by David Wong, www.davidwongart.com

African Sleeping Sickness, also referred to as African trypanosomiasis, is a disease caused by protozoan parasites that are passed to humans by tsetse flies. Tsetse flies are located in Sub-Saharan Africa and are found around plants by rivers and lakes as well as in forests and wooded areas. Trypanosoma brucei gambiense, in western and central Africa, and Trypanosoma brucei rhodesiense, in eastern and southern Africa, are the parasites that cause human disease. T.b. gambiense causes chronic sleeping sickness, for which symptoms can take months to years to appear. T.b. rhodesiense, on the other hand, causes acute disease with symptoms appearing in weeks to a few months. Tsetse fly range picture from www.indiana.edu/~origins/teach/P380/P380Africainfo.html

Infection starts with a bite from an infected tsetse fly that develops into a sore. As the trypanosomes multiply in the bloodstream, symptoms such as headaches, joint pain, fever, and itching can occur. When the parasites cross the blood-brain barrier into the central nervous system mental impairment, lethargy, and coma can result. If the disease is left untreated, an infected person will die. A few drugs are available to treat the early stages of infection (while the parasite are only in the bloodstream) and for the late stage (after the parasites cross the blood-brain barrier). The early stage drugs are more effective and less toxic while late stage drugs are more toxic and less effective, although all are difficult to administer and resistance is developing. Since African trypanosomiasis is invariably fatal if not treated and current drugs are toxic, difficult to administer, and resistance is developing, it is essential to do basic research in order to better understand parasite biology and to identify unique and essential targets that may serve as starting platforms for new drug therapies. In our laboratory, we study many processes in T. brucei that are important to its survival.

Trypanosomes have four life cycle stages due to their transition from tsetse flies to humans and back again, two of which can be cultured in the lab. During these different life cycle stages, extensive remodeling of both nuclear and mitochondrial gene expression occurs, and the mitochondria undergo dramatic morphological changes. The figure on the left, from the CDC www.dpd.cdc.gov/dpdx/HTML/TrypanosomiasisAfrican.htm, displays these life cycle stages.

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