Definition of Sleeping sickness:

Sleeping sickness is infection with organisms carried by certain flies. It results in swelling of the brain.

Causes, incidence, and risk factors:

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

Tsetse flies carry the infection. When an infected fly bites you, painful, red swelling occurs at the site of the bite. The infection then spreads through your blood, causing episodes of fever, headache, sweating, and swelling of the lymph nodes.

When the infection spreads to the central nervous system, it causes the symptoms typical of sleeping sickness (see below). When it reaches the brain, behavioral changes such as fear and mood swings occur, followed by headache, fever, and weakness. Inflammation of the heart ( myocarditis) may develop.

Risk factors include living in parts of Africa where the disease is found and being bitten by tsetse flies. The disease is extremely rare in the United States, and is only found in travelers who have visited or lived in those African areas.