Human African trypanosomiasis, known as sleeping sickness, is caused by trypanosomes, which are protozoan parasites spread by the tsetse fly. The flies live in Africa and are found in vegetation by rivers and lakes, forests, and wooded savannah.
Sleeping sickness is a daily threat to more than 60 million men, women, and children in 36 countries of sub-Saharan Africa, 22 of which are among the least developed countries in the world. Some 300,000 to 500,000 people may develop disease each year.
Another human form of the disease, human American trypanosomiasis, occurs in the Americas and is known as Chagas disease.
When a person becomes infected they have bouts of fever, headaches, pains in the joints, and itching as the parasites multiply in the blood and lymph glands. In the second phase of the disease, the parasite crosses the blood-brain barrier and infects the central nervous system. This is when the characteristic signs and symptoms of the disease appear including confusion, sensory disruption, and poor coordination. Disturbance of the sleep cycle, which gives the disease its name, is the most salient feature.
Without treatment, the disease is usually fatal. If the disease is diagnosed early, the chances of cure are high. However, if the patient does not receive treatment before the onset of the second phase, neurological damage is irreversible even after treatment. Unfortunately, treatment of trypanosomes is leading to increased drug resistance, which limits therapeutic success.