COMMENTS
WEST AFRICAN (CHRONIC & PRIMARY RESERVOIR HUMAN & 95% OF CASES)
West African trypanosomiasis is a chronic disease lasting months to years with two distinct stages: hemolymphatic and meningoencephalitic. The inoculation chancre is not frequently seen in clinical practice. The chancre may ulcerate to reach a size of several centimeters, and it may be associated with regional lymphadenopathy. The onset of fever marks the beginning of the first stage. Winterbottom’s sign is the presence of lymphadenopathy in the posterior cervical triangle. A rash is often present on the trunk, shoulders, buttocks, and thighs. Typically, the rash consists of patches of erythema 5-10 cm in diameter with central clearing. Symptoms in the second stage include irritability, inability to concentrate, severe headache, impaired speech, tremors, fasciculations, ataxia, stupor, and coma.
EAST AFRICAN (ACUTE & PRIMARY RESERVOIR ANIMAL & 5% OF CASES):
East African trypanosomiasis is an acute disease lasting less than 9 months. Recurrent fever and rash are present in both East and West forms, but lymphadenopathy is not prominent in East African trypanosomiasis. Leukocytosis is usually present during the first few months of infection. [PPID, p. 3351-2, Table 277.1] The "inoculation chancre," a painful, indurated nodule at the site of the tsetse fly bite, is more commonly recalled in patients with the East African form. [Guerrant, p. 685]
LABORATORY:
Patients with African trypanosomiasis often have anemia and hypergammaglobulinemia. Lymph node aspiration is the classic procedure for diagnosis. Another method is to exam the buffy coat of a centrifuged specimen of blood. Patients with East African trypanosomiasis have a higher level of parasitemia making it easier to detect the disease in blood smears. . In chronic cases of West African trypanosomiasis, parasites become increasingly rare in blood or lymph node aspiration, but can be found in the CSF. [Guerrant, p. 685-6]
COMPLICATIONS:
Meningoencephalitis develops either a few weeks to months after the bite (East African form) or months to years after the bite (West African form). Myocarditis also develops. "CNS involvement causes persistent headache, inability to concentrate, personality changes (eg, progressive lassitude and indifference), daytime somnolence, tremor, ataxia, and terminal coma." Without treatment, death ensues. [Merck Manual, p. 1543] In the late stages of West African sleeping sickness, patients may develop paralysis and die from aspiration pneumonia. [Cecil, p. 2083] Thrombocytopenia and elevated liver transaminases are typical laboratory findings. Patients with East African trypanosomiasis often die from congestive heart failure, arrhythmias, and secondary infections before CNS infection has occurred. [ID, p. 164, 2328] CNS symptoms include a disturbed cycle of sleeping, paresthesias, movement disorders, slurred speech, lethargy, and delirium. [Cohen, p. 1762] 10%-20% of patients have splenomegaly. Hepatomegaly is rare. The rash, usually appearing 6-8 weeks after being infected, can be seen only in Caucasian patients. Seizures in children are fairly common. Bacterial pneumonia is a complication. [Guerrant, p. 685-7]
EPIDEMIOLOGY:
Tsetse flies live in rural areas. [CDC Travel, p. 353] "With few exceptions, this infection is never found in urban areas." [Cecil, p. 2082] Animal reservoirs include wild animals, cattle, and other domestic animals for the East African form, a zoonosis and a disease of hunters, fishers, honey collectors, and visitors to wild game parks. Humans are the reservoirs for the West African form. Infected blood is a laboratory hazard, but transfusion or congenital infections are rarely reported. [CCDM, p. 630-31]
SCOPE
T.b. rhodesiense: E. & SE Africa (Tanzania, Uganda, Malawi, Zambia, Zimbabwe); T.b. gambiense: central Africa & foci in West Africa (DRCongo, Congo, Angola, S. Sudan, Central African Republic, Guinea, Cameroon, Chad, & N. Uganda); [CDC Travel]