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. 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.
— Anne
Moore
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