Genetic diversity of Trypanosoma cruzi in individuals with chronic Chagas disease in the Northern Minas Gerais and Vale do Jequitinhonha regions, Minas Gerais, Brazil

Abstract

Chagas disease, caused by the hemoflagellate parasite Trypanosoma cruzi, is a major public health problem in Latin America due to its high prevalence and significant morbidity and mortality. The T. cruzi is classified into seven distinct genetic groups (TcI-TcVI) and TcBat, know as Discrete Typing Units (DTUs). Understanding DTU diversity is essential for improving diagnostic and therapeutic strategies and strengthening epidemiological surveillance. This study aimed to investigate the genetic diversity of T. cruzi in individuals with chronic Chagas disease from endemic municipalities in Northern Minas Gerais and the Jequitinhonha Valley, Brazil. It also evaluated associations between DTUs and age, parasitic load, antibody levels, and cardiac disease severity in participants from the SaMi-Trop cohort. Molecular typing was performed using conventional multilocus PCR directly from peripheral blood samples of individuals with the chronic cardiac form. Of the 80 patients included in the study, T. cruzi genotyping was performed in 37 samples (46.25%). Among the samples in which a single DTU was identified, TcI and TcVI presented equal frequen-cies (n = 5, 13.51% each). TcII was identified in four samples (n = 4, 10.81%), while TcV was identified in three samples (n = 3, 8.10%). Furthermore, three individuals presented mixed infections: TcV + TcVI, TcI + TcV + TcII/TcVI, and TcV + TcII. The highest frequency was observed for TcII/TcVI (n = 17, 45.94%), a classification that does not represent mixed infection. For statistical analysis, TcII/TcVI samples were classified as TcII. No significant differences were found between the DTUs and age or parasitic load. However, a wide variation in the average parasitic load was observed among individuals, ranging from 0.06 to 667 parasite equivalents/mL. An increase in anti-T. cruzi antibody titers was also observed. The findings of this study demonstrate the genetic diversity of the parasite in individuals with chronic cardiac Chagas disease and its distribution in a highly endemic region.