Clinical Features:
Infection occurs in 3 stages.  A trypanosomal chancre can develop on the site of inoculation.  This is followed by a hemolymphatic stage with symptoms that include fever, lymphadenopathy, and pruritus.  In the meningoencephalitic stage, invasion of the central nervous system can cause headaches, somnolence, abnormal behavior, and lead to loss of consciousness and coma.  The course of infection is much more acute with T. b. rhodesiense than T. b. gambiense.

Laboratory Diagnosis:
The diagnosis rests upon demonstrating trypanosomes by microscopic examination of chancre fluid, lymph node aspirates, blood, bone marrow, or, in the late stages of infection, cerebrospinal fluid.  A wet preparation should be examined for the motile trypanosomes, and in addition a smear should be fixed, stained with Giemsa (or Field), and examined.  Concentration techniques can be used prior to microscopic examination.  For blood samples, these include centrifugation followed by examination of the buffy coat; mini anion-exchange/centrifugation; and the Quantitative Buffy Coat (QBC) technique.  For other samples such as spinal fluid, concentration techniques include centrifugation followed by examination of the sediment.  Isolation of the parasite by inoculation of rats or mice is a sensitive method, but its use is limited to T. b. rhodesiense.  Antigen detection assays, in a test format suitable for field use, are being developed and evaluated.  Antibody detection has sensitivity and specificity that are too variable for clinical decisions.  In addition, in infections with T. b. rhodesiense, seroconversion occurs after the onset of clinical symptoms and thus is of limited use.  However, the Card Agglutination Trypanosomiasis Test (CATT) test is of value for epidemiologic surveys or screening of T. b. gambiense.

Diagnostic findings

• Microscopy
• Case history 20-2002 from the New England Journal of Medicine (http://www.nejm.org) Vol. 346, No. 26, June 27, 2002.

Treatment:
Treatment should be started as soon as possible and is based on the infected person’s symptoms and laboratory results.  The drug regimen depends on the infecting species and the stage of infection.  Pentamidine isethionate* and suramin (under an investigational New Drug Protocol from CDC's 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. rhodiense).  See recommendations in The Medical Letter for complete information.

* This drug is approved by the FDA, but considered investigational for this purpose.