The CDC divides sleeping sickness into two different diseases. East African sleeping sickness is caused by Trypanosoma brucei rhodesiense , but West African sleeping sickness is caused by Trypanosoma brucei gambiense. Apart from this difference the diseases are very similar

When a tsetse fly infected with the protozoa that causes sleeping sickness bites a human the organism is transferred. The bite of a tsetse fly is easily noticable by the pain it causes, and the red swelling that may develop afterwards.

It is theoretically possible for the infection to be passed in bodily fluids, whether in a blood transplant, from a mother to her child or any other concievable way. Because death occurs fairly soon after infection this method of transmission is uncommon.

Symptoms may begin to occur from between 7-30 days of infection. The most common of these are:

If no treatment takes place, death typically occurs after several more weeks or months.

Sleeping sickness must be caught early if the sufferer is to survive. Diagnosis is usually by lab examination of CS fluid. Treatment involves the use of drugs, the specific combination depending on which type of sleeping sickness is present. All of these drugs cause extensive and undesirable side-effects, but this is considered more desirable than the alternative of near certain death.

No vaccine exists for sleeping sickness, and immunity does not develop. Aside from staying out of Africa, the best way to avoid contracting sleeping sickness is the prevention of fly bites. This can be accommplished by wearing covering clothing, and sleeping in locations protected by netting. Tsetse flies tend to live in bushes, so not disturbing undergrowth is a sensible measure.

Cases of sleeping sickness have risen in central African countries since they gained independence. Due to poor recording of statistics regarding the disease it is difficult to accurately estimate how many cases there are per year. It is thought that as many as 20 000 people per year could die due to sleeping sickness.

Collins Medical Encyclopaedia