Abstract
BackgroundAmerican Trypanosomiasis or Chagas disease is caused by Trypanosoma cruzi which currently infects approximately 16 million people in the Americas causing high morbidity and mortality. Diagnosis of American trypanosomiasis relies on serology, primarily using indirect immunofluorescence assay (IFA) with T. cruzi epimastigote forms. The closely related but nonpathogenic Trypanosoma rangeli has a sympatric distribution with T. cruzi and is carried by the same vectors. As a result false positives are frequently generated. This confounding factor leads to increased diagnostic test costs and where false positives are not caught, endangers human health due to the toxicity of the drugs used to treat Chagas disease.ResultsIn the present study, serologic cross-reactivity between the two species was compared for the currently used epimastigote form and the more pathologically relevant trypomastigote form, using IFA and immunoblotting (IB) assays. Our results reveal an important decrease in cross reactivity when T. rangeli culture-derived trypomastigotes are used in IFA based diagnosis of Chagas disease. Western blot results using sera from both acute and chronic chagasic patients presenting with cardiac, indeterminate or digestive disease revealed similar, but not identical, antigenic profiles.ConclusionThis is the first study addressing the serological cross-reactivity between distinct forms and strains of T. rangeli and T. cruzi using sera from distinct phases of the Chagasic infection. Several T. rangeli-specific proteins were detected, which may have potential as diagnostic tools.
Highlights
American Trypanosomiasis or Chagas disease is caused by Trypanosoma cruzi which currently infects approximately 16 million people in the Americas causing high morbidity and mortality
Independent of the clinical form, all chagasic sera tested reacted with both T. cruzi and T. rangeli epimastigotes in immunofluorescence assay (IFA) (Figs. 1 and 2)
The use of T. rangeli trypomastigote forms as antigen reduced the cross-reactivity of serum from patients with the cardiac form of the Chagas disease to 30.76% (8/26)
Summary
American Trypanosomiasis or Chagas disease is caused by Trypanosoma cruzi which currently infects approximately 16 million people in the Americas causing high morbidity and mortality. The closely related but nonpathogenic Trypanosoma rangeli has a sympatric distribution with T. cruzi and is carried by the same vectors. Parasites & Vectors 2008, 1:20 http://www.parasitesandvectors.com/content/1/1/20 humans while T. cruzi is the etiological agent of Chagas disease and infects over 16 million people in the new world [4]. Several reports pointed out the sharing of antigenic epitopes by T. cruzi and T. rangeli [9,10,11,12] These studies were performed with sera from animals immunized with T. rangeli epimastigotes rather than infected or immunized with the trypomastigote forms present in infected hosts [9,10,11,12]. It is widely accepted to have an outstanding but underestimated impact on the diagnosis of Chagas disease [2,9,10,11,12,13,14]
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