# Molecular characterisation of Trypanosoma cruzi in Triatoma dimidiata from a highland locality in western Panamá

## TL;DR

This study found that 70% of Triatoma dimidiata bugs in western Panamá were infected with Trypanosoma cruzi, suggesting active local transmission of the parasite.

## Contribution

The first molecular confirmation of T. cruzi in T. dimidiata from Palmira Arriba, highlighting active transmission in highland regions.

## Key findings

- 21 out of 30 triatomines tested positive for Trypanosoma cruzi.
- Most infections were linked to domestic and sylvatic cycles (TcI and TcIa genotypes).
- Blood meal analysis showed opportunistic feeding on mammals and birds.

## Abstract

Triatoma dimidiata is a widely distributed vector of Trypanosoma cruzi in Mesoamerica, but its epidemiological role in most regions of Panamá remains poorly understood.

To investigate the presence, infection status, and feeding behaviour of T. dimidiata populations in peridomestic areas of Palmira Arriba, western Panamá.

Entomological surveys were conducted in five peridomestic sites of a rural highland community. Thirty-seven triatomines (13 adults and 24 nymphs) were collected from wooden piles and construction materials in contact with the ground. DNA from 30 specimens was analysed by polymerase chain reaction (PCR) for T. cruzi detection, genotyping [discrete typing unit (DTU) and haplotype identification], and blood meal source determination through cytochrome b amplification.

Twenty-one insects (70.0%) were positive for T. cruzi. Sixteen infections (76.2%) belonged to DTU I (TcI), including 13 TcIDOM and 14 TcIa genotypes, both linked to domestic and sylvatic cycles. Blood meal analysis revealed one mammalian and two avian feedings, indicating opportunistic behaviour.

This study provides the first molecular confirmation of T. cruzi infection in T. dimidiata from Palmira Arriba. The combination of high infection prevalence, multiple developmental stages, and recent feeding suggests active local transmission favoured by humid and cool ecological conditions. Expanded surveillance and integrative One Health approaches are needed to elucidate transmission dynamics in highland rural Panamá.