Molecular Approaches for Diagnosis of Chagas’ Disease and Genotyping of Trypanosoma cruzi

Abstract

Chagas' disease, or American trypanosomiasis, is a vector-borne parasite infection caused by the protozoan Trypanosoma cruzi, which affects about 7 to 8 million people, mainly in Latin America. The parasite is primarily transmitted by different species of triatomine bugs (Insecta: Hemiptera: Reduviidae: Triatominae). However, T. cruzi infection can also be acquired congenitally, by oral transmission (from consumption of food contaminated with infected triatomine bug feces), by blood transfusions, and by organ transplantation (1). T. cruzi is a highly diverse species, and six major lineages, or discrete typing units (DTUs) (TcI to TcVI), have been described for this parasite. During its life cycle, T. cruzi infects both insect vectors and mammalian hosts and undergoes morphological and functional changes. Three main morphological forms of the parasite are recognized, namely (i) amastigotes (intracellular replicative forms in mammalian tissues), (ii) trypomastigotes (nonreplicative forms: metacyclic trypomastigote in the rectum of triatomine vectors and bloodstream trypomastigotes in mammalian blood), and (iii) epimastigotes (replicative forms found in the triatomine midgut). Intermediate forms are also recognized (2).