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Key Features

Essentials of Diagnosis

  • Exposure to tsetse flies; chancre at bite site uncommon

  • Hemolymphatic disease: Irregular fever, headache, joint pain, rash, edema, lymphadenopathy

  • Meningoencephalitic disease: somnolence, severe headache, progressing to coma

  • Trypanosomes in blood or lymph node aspirates; positive serologic tests

  • Trypanosomes and increased white cells and protein in cerebrospinal fluid (CSF)

General Considerations

  • African trypanosomiasis is caused by the hemoflagellates Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense

  • T b gambiense causes West African trypanosomiasis and is transmitted in the moist sub-Saharan savannas and forests of west and central Africa

  • Organisms are transmitted by bites of tsetse flies (Glossina species), which inhabit shaded areas along rivers

  • Humans are the principal mammalian host, but domestic animals can be infected

  • Trypanosomes ingested in a blood meal undergo a developmental period of 18–35 days in the fly

  • When the fly feeds again on a new mammalian host, the infective stage is injected

Demographics

  • The number of reported cases increased from the 1960s to1990s, and has since decreased greatly, although cases are reported from over 20 countries

  • Total incidence has been estimated at about < 5000 cases per year, the large majority due to T b gambiense, with the largest number in the Democratic Republic of the Congo

  • Infections are rare among travelers

Clinical Findings

Symptoms and Signs

  • Chancres at the site of the bite are uncommon

  • Patient may be asymptomatic for months before hemolymphatic disease develops

  • Hemolymphatic disease progresses to meningoencephalitic disease, which leads to coma and death

Hemolymphatic disease

  • Fever, headache, myalgias, arthralgias, weight loss, and lymphadenopathy

  • Discrete, nontender, rubbery nodes, referred to as Winterbottom sign when in a posterior cervical distribution

  • Mild splenomegaly

  • Transient edema

  • Pruritic erythematous rash

  • Febrile episodes may be broken by afebrile periods of up to several weeks

Meningoencephalitic disease

  • Somnolence, irritability, personality changes

  • Severe headache

  • Parkinsonian symptoms

Differential Diagnosis

  • T b rhodesiense infection

  • Malaria

  • Influenza and pneumonia

  • Tuberculosis

  • Infectious mononucleosis

  • Leukemia or lymphoma

  • HIV

  • Arbovirus encephalitis

  • Wilson disease

  • Psychosis due to other causes, eg, neurosyphilis

Diagnosis

Laboratory Tests

  • During the hemolymphatic stage, detection of parasites in Giemsa-stained blood smears is difficult

  • Serial specimens should be examined, since parasitemias vary greatly over time

  • Meningoencephalitic (or second stage) disease is defined by the World Health Organization as CSF showing at least 5 mononuclear cells per mcL, elevated protein, or trypanosomes

  • Concentration techniques can aid identification of parasites in blood or CSF

  • Serologic tests are positive

  • The simple card agglutination test for trypanosomes (CATT)

    • Has excellent sensitivity and specificity

    • Can be performed in the field

    • However, the diagnosis should be confirmed by identification of the parasites

  • Field-applicable immunochromatographic lateral ...

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