Biological and Molecular Characterization of Five Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida, Trypanosomatidae) Isolates from the State of Hidalgo, Mexico

<i>Trypanosoma cruzi</i>, the causal agent of Chagas disease, exhibits great genetic diversity, which has been related to its biological properties. However, these are poorly known in strains from the endemic area of Hidalgo. To assess the parasite's virulence, we evaluated parasitemia, mortality, and tropism in thirteen organs of CD1 mice during the acute phase of infection. For genotyping, we amplified the mini-exon gene from <i>T. cruzi</i> DNA using PCR. All five isolates were identified as belonging to DTU TcI. The peak of parasitemia occurred between 25 and 29 days post-infection. The Tultitlán and Olma isolates did not cause any mouse deaths, whereas Ixcatépec produced 100% mortality. Mice infected with the Barrio Hondo isolate exhibited the highest parasitemia, while those infected with Cuatecomaco had the lowest. The five isolates generated varying degrees of infection and chronic inflammation; only two isolates triggered acute pancreatitis and myocarditis. No amastigote nests were found in the hearts of mice infected with the Ixcatépec isolate. Our findings suggest that the damage caused by <i>T. cruzi</i> strains from Hidalgo may extend beyond cardiac lesions in the acute phase of Chagas disease regardless of their classification as TcI and variability in parasitemia levels.