Description
Trypanosomiasis is a systemic disease caused by the parasite Trypanosoma brucei. East African trypanosomiasis is caused by T. b. rhodesiense, and West African trypanosomiasis by T. b. gambiense. It is transmitted by the bite of the tsetse fly, a gray-brown insect about the size of a honeybee.
Occurrence
African trypanosomiasis is confined to tropical Africa between 15° north latitude and 20° south latitude, or from north of South Africa to south of Algeria, Libya, and Egypt. According to WHO 45,000 cases of trypanosomiasis were reported in 1999, however the actual prevalence of cases is estimated to be between 300,000 to 500,000.
Risk for Travelers
Tsetse flies inhabit rural areas only, living in the woodland and thickets of the savannah and the dense vegetation along streams. Although infection of international travelers was considered rare, the number of cases in travelers, primarily to East African game parks, has increased in recent years. Approximately 1 case per year has been reported among U.S. travelers. Travelers visiting game parks and remote areas should be advised to take precautions. Travelers to urban areas are not at risk.
Clinical Presentation
Signs and symptoms are initially nonspecific (fever, skin lesions, rash, edema, or lymphadenopathy); however, the infection progresses to meningoencephalitis. Symptoms generally appear within 1 to 3 weeks of infection. East African trypanosomiasis is more acute clinically, with earlier central nervous system involvement than in the West African form of the disease. Untreated cases are eventually fatal.
Prevention
No vaccine is available to prevent this disease. Tsetse flies are attracted to moving vehicles and dark, contrasting colors. They are not affected by insect repellents and can bite through lightweight clothing. Areas of heavy infestation tend to be sporadically distributed and are usually well known to local residents. Avoidance of such areas is the best means of protection. Travelers at risk should be advised to wear clothing of wrist and ankle length that is made of medium-weight fabric in neutral colors that blend with the background environment.
Treatment
Travelers who sustain tsetse fly bites and become ill with high fever or other manifestations of African trypanosomiasis should be advised to seek early medical attention. The infection can usually be cured by an appropriate course of anti-trypanosomal therapy. Pentamidine isethionate (approved by the FDA, but considered investigational for this purpose) and suramin (under an investigational New Drug Protocol from the CDC Drug Service) are the drugs of choice to treat the hemolymphatic stage of West and East African trypanosomiasis, respectively. Melarsoprol is the drug of choice for late disease with central nervous system involvement (infections by T.b. gambiense or T.b. rhodesiense. Travelers should be advised to consult an infectious disease or tropical medicine specialist.