Trypanosomiasis diagnosis

The limit of detection of the assay was estimated to be 200 parasites/ml of blood. The detection limit is well within the range of sensitivity needed to diagnosis trypanosomiasis, as the parasitemia may vary from 5000 to 1,500,000 parasites/ml (Vickerman, 1974). The bDNA assay was compared with buffy coat microscopy for detection of T brucei in 56 blood samples (36 buffy coat positive and 20 buffy coat negative by microscopy). There was complete concordance between the results of the two tests in terms of identifying specimens as positive of negative. However, the numbers of parasites observed by microscopy were lower overall than those calculated with the bDNA assay. The authors suggested that the excess of leukocytes in the buffy coat could interfere with the microscopic detection of typanosomes, resulting in lower apparent parasitemia than the true value. 

Indeed, a bDNA assay for diagnosis of African trypanosomiasis was developed and compared with buffy coat microscopy for detection of T brucei in human blood samples (Harris etal., 1996). Two repetitive DNA sequences found only in the T. brucei complex, a 177-bp satellite repeat and the ribosomal mobile element, were selected as targets in the bDNA assay. The assay used the standard bDNA components capture probes, target probes, amplifier molecules, and alkaline phosphatase-labeled probes. Various blood fractions and sample preparation methods were examined. Ultimately, buffy coat samples resulted in the highest sensitivity. Although typanosomes do not infect leukocytes, they cosediment with them. 

Aspirates of bone marrow or spleen may be useful in the diagnosis of infections such as leishmaniasis, trypanosomiasis, and occasionally malaria. In such instances, Giemsa stains of alcohol-fixed bone marrow films are most useful. Splenic aspiration is rajrely performed in the United States because it is dangerous. 

Suggested Alternatives for Differential Diagnosis Dengue, measles, Rocky Mountain spotted fever, rubella, tick bite fever, epidemic typhus, Q fever, typhoid, malaria, trypanosomiasis, hepatitis, infectious mononucleosis, herpes, and influenza. 

Suggested Alternatives for Differential Diagnosis Anthrax, tetanus, rabies, meningitis, encephalitis, cerebral trypanosomiasis, piroplasmosis, theileriosis, listeriosis, parasitism poisoning by strychnine, lead, organophosphates, arsenic, and various plants that affect the central nervous system. 

Conclusion. In African trypanosomiasis there is a very marked increase of the serum IgM—about 10-20 times the normal level. Estimation of the serum IgM can be regarded as a very useful test in the diagnosis of African sleeping sickness. The concentration of serum IgG is slightly raised and serum IgA is normal. In the tropics, trypanosomiasis may be regarded as one of the chief factors which contribute to secondary macroglobulinaemia. 

The diagnosis of trypanosomiasis is based on the direct demonstration of the parasite or on serology. Direct detection includes the examination of blood smears, anion-exchange chromatography or mouse inoculation. The latter method is... 

THERAPEUTIC USES Melarsoprol is the only effective drug available for treatment of the late meningoencephaMtic stage of East African (Rhodesian) trypanosomiasis. Melarsoprol treatment of East African trypanosomiasis is initiated soon after diagnosis because CNS involvement occurs early in this aggressive infection. Melarsoprol is not used for prophylaxis because of its toxicity and rapid elimination. 

Kennedy PG (2013) Clinical features, diagnosis, and treatment of human African trypanosomiasis (sleeping sickness). Lancet Neurol 12(2) 186-194 Krauth-Siegel LR, Comini MA, Schlecker T (2007) The trypanothione system. Subcell Biochem 44 231-251... 

African sleeping sickness (Trypanosomiasis) Tsetse fly The bite of the tsetse fly can be very painful. The disease is treatable, but diagnosis in travelers can be missed... 

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