Trypanosomiasis
Trypanosomiasis is caused by infection by protozoan parasites called trypanosomes spread, in Africa, by the tsetse fly and in South America by large blood sucking insects called triatomine. In Africa the bite of the tsetse fly initially produces a raised spot. Over a week or so the parasites multiply and are spread in the bloodstream causing enlargement of the liver and spleen and the lymph glands. Later they may invade the brain, causing neurological symptoms and eventually apathy, stupor, coma and then death - this is so called sleeping sickness.
In South America the germ is not spread by the bite of the blood-sucking insect, but is excreted in its faeces which deposits as it feeds. The faeces are then introduced into the bite wound when the sufferer rubs it. There may be an initial period involving fever and sweating over a week or so, but often there is no sign of infection until many years later when it attacks the heart, the intestine and the nervous system. This is called Chagas disease, and it affects many millions of people in the poor rural areas of Central and South America. The early stages can be treated. Increased hygiene and eradication of the insects may help prevent the disease.
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