Sleeping Sickness

Overview, Causes, & Risk Factors

Sleeping sickness is caused by two organisms, T. brucei rhodesiense and T. brucei gambiense. The more severe form of the illness is caused by rhodesiense.

After a person is bitten by an infected fly, a red painful swelling develops at the site of the fly bite, similar to that seen in Chagas disease. From this site, the parasite invades the blood stream, causing episodes of fever, headache, sweating, and generalized enlargement of the lymph nodes. Parasites then invade the central nervous system (early with rhodesiense and later with gambiense) where they produce the symptoms typical of sleeping sickness.

Ultimately the parasites invade the brain, first causing behavioral changes such as fear and mood swings, followed by headache, fever, and weakness. Simultaneously, the patient may develop myocarditis.

Without treatment, death may occur within six months from cardiac failure, or from rhodesiense infection itself. Gambiense infection may require up to two years before symptoms of infection in the central nervous system appear.

Gambiense-infected people develop drowsiness during the day, but insomnia at night. Sleep becomes uncontrollable as the disease progresses until the patient becomes comatose.

Risk factors include living in those parts of Africa where the disease is found and being bitten by tsetse flies. The incidence is extremely low in the U.S. -- it is only found in travelers who have visited or lived in those areas.