Trypanosomiasis is a disease caused by parasitic protozoa of the family Trypanosomidae, which also contains the protozoa that cause leishmaniasis. In humans, two variations of Trypanosoma bruceiÑT. b. gambiense and T. b. rhodesienseÑcause African sleeping sickness, while T. cruzi causes Chagas disease, or South American trypanosomiasis. Both T. brucei and T. vivax, which cause animal
Trypanosomiasis in Africa, have spread to South America.
African sleeping sickness is transmitted by the
bite of an infected tsetse fly. In
humans the first symptom is a local inflammation (trypanosomal chancre) at the site of the bite. Systemic symptoms follow, such as fever and chills, headache, edema of the extremities, and
enlargement of the lymph glands.
Damage to the central
nervous system may take years to develop, but it is manifested by sleepiness, lethargy, headache, and eventually motor disturbances, convulsions, and coma; without treatment, the disease is fatal. Antimicrobial agents are effective against trypanosomiasis if given early in the disease. A drug to treat the West African form of the disease has been available since 1990. Vaccine research is complicated by the parasite's ability to alter its antigens once inside a host.
Chagas disease is transmitted to humans by a predatory bug, Triatoma; the bite wound is contaminated by the insect's feces, which contain the parasite. T. cruzi is carried by both wild and domesticated animals. The disease is characterized by fever, spleen and liver enlargement, and nervous-system and heart-muscle damage. The acute form of the disease is usually confined to children and can be fatal. No universally effective treatment exists.
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