Molecular Characterization of Trypanosoma cruzi from Triatomine Species in São Paulo State, an Area Free of Vector-Borne Chagas Disease

TL;DR

This study found that certain insects in São Paulo can still spread Chagas disease, despite efforts to control the main carriers, highlighting the need for continued monitoring.

Contribution

The study reveals high T. cruzi infection rates in non-target triatomine species in urban and rural areas of São Paulo.

Findings

A 65% T. cruzi infection rate was found in Panstrongylus megistus collected from homes and surrounding areas.

The DTU TcI genotype was the most prevalent in the studied region.

Triatomines collected from palm trees showed no T. cruzi infection.

Abstract

This study focused on understanding how common the parasite Trypanosoma cruzi (which causes Chagas disease) is in certain insects called triatomines, by analyzing their feces. Samples were collected from 570 triatomines in 25 cities in São Paulo and tested for the parasite’s DNA. A low overall infection rate was found (3.2%); however, excluding the insects collected in palm trees, where no positives were found, the infection rate was very high among those collected in residences and peridomiciles (45%), the majority of which were Panstrongylus megistus, and 65% of them were positive for T. cruzi. These findings are important because although the main vectors of Chagas disease have been controlled, other insect species are still capable of spreading the disease, especially in both city and rural areas. This highlights the need for ongoing monitoring of these insects to prevent a resurgence of Chagas disease in São Paulo, protecting public health.

Chagas disease (ChD) is a neglected tropical disease caused by Trypanosoma cruzi, endemic in 21 countries across the Americas, with increasing cases globally. In São Paulo, Brazil, vector control has focused on Triatoma infestans, but secondary triatomine species continue to pose transmission risks. This study aimed to investigate the prevalence of T. cruzi in triatomine feces and characterize its genetic diversity using molecular techniques. Fecal samples were collected from 570 triatomines across 25 municipalities in São Paulo, followed by DNA extraction and PCR amplification targeting the mitochondrial cytochrome b gene and the V7V8 region of the 18S rRNA gene. The results revealed a low overall infection rate (3.2%). However, excluding the triatomines collected in palm trees, all of which were negative, we found mainly Panstrongylus megistus in residences and peridomiciles, showing the highest infection rate (65%) for T. cruzi, followed by Triatoma sordida and Rhodnius neglectus. Phylogenetic analysis confirmed that DTU TcI was the most prevalent genotype, consistent with previous findings in the region. This study highlights the importance of continued vector surveillance, as these secondary species are capable of maintaining T. cruzi transmission in both urban and rural environments, underscoring the ongoing risk of ChD resurgence in São Paulo.

Figures