Risk of Trypanosoma cruzi transmission in southern Minas Gerais, Brazil - Data from 2014 to 2020

Trypanosoma cruzi, the etiologic agent of Chagas disease, is widely distributed in the Americas and is transmitted through vectorial, transfusional, and oral routes. This study aimed to evaluate the risk of vectorial transmission of Chagas disease in municipalities located in southern Minas Gerais, Brazil, by analyzing triatomine specimens collected from 2014 to 2020. All 1522 hematophagous triatomines were identified as Panstrongylus megistus, and were subjected to parasitological and molecular examinations. From 2014 to 2016, approximately 10% of insects were positive in the microscopic analysis of intestinal content, and 27% were positive as detected by the quantitative polymerase chain reaction (qPCR) of the same sampling. However, in the last investigated years, an increase in infected triatomines was observed in microscopic analysis (22%) and qPCR methods (41%). This corroborates the findings of acute human Chagas disease cases, which have increased in the study area from a maximum of 2 cases in previous years to 20 cases in 2019, and 17 cases in 2020 through June. Additionally, bloodmeal sources of infected triatomines were investigated; human blood was detected in up to 85.7% of the samples. Moreover, canine blood was also detected in triatomine intestinal content in recent years, reaching 91% of analyzed insects in 2018. Data on bloodmeal sources have demonstrated human-vector contact and have suggested the participation of dogs in the parasite transmission cycle. These results indicate the risk of T. cruzi vectorial transmission in Southern Minas Gerais and Sao Paulo owing to the boundary between these states. Thus, enhanced surveillance and vector control of Chagas disease are highly recommended in these areas.