African Trypanosomiasis (African Sleeping Sickness)

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 . Both forms are 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, 25,000-45,000 cases of trypanosomiasis are reported annually; however, the actual prevalence of cases is estimated to be 300,000 to 500,000.

Risk for Travelers

Tsetse flies inhabit rural areas, living in the woodland and thickets of the savannah and the dense vegetation along streams. Infection of international travelers is rare. Approximately 1 case per year is reported among U.S. travelers. Most of these infections are caused by T. b. rhodesiense and they are acquired in East African game parks. 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. The drug of choice for treatment of East African trypanosomiasis is suramin (for the hemolymphatic stage) or melarsoprol (for late disease with central nervous system involvement). These drugs are available under an Investigational New Drug protocol from the CDC Drug Service. West African trypanosomiasis is best treated with pentamidine isethionate (for the hemolymphatic stage) or eflornithine. Travelers should be advised to consult an infectious disease or tropical medicine specialist.

Bibliography

• Lejon V, Boelaert M, Jannin J, et al. Diagnosis of imported sleeping sickness. Lancet Infect Dis . 2003;3:804-8.
• Moore A. Human African trypanosomiasis: a reemerging public health threat. In: Scheld WM, Murray BE, Hughes J, editors. Emerging Infections VI . Washington, DC: ASM Press; 2004. p. 143-57.
• Moore A, Ryan ET, Waldron MA. A 37-year-old man with fever, hepatosplenomegaly, and a cutaneous foot lesion after a trip to Africa. N Engl J Med . 2002;346:2069-76.
• Moore DAJ, Edwards M, Escombe R, et al. African trypanosomiasis in travelers returning to the United Kingdom. Emerg Infect Dis . 2002;8:74-6.
• Sinha A, Grace C, Alston WK, et al. African trypanosomiasis in two travelers from the United States. Clin Infect Dis . 1999;29:840-4.
• Van Nieuwenhove S. Present strategies in the treatment of human African trypanosomiasis. In: Dumas M, Bouteille B, Buguet A, editors. Progress in human African trypanosomiasis, sleeping sickness . Paris: Springer Verlag; 1999. p. 253-80.

- Anne Moore