Triatoma Williami Galvão, Souza e Lima, 1965 (Hemiptera, Triatominae) in Intradomiciliary Environments of Urban Area in Mato Grosso State, Brazil Domiciliation Process of a Wild Species?

Abstract

Background: Triatomines found throughout Latin America are natural Chagas disease vectors (ChD). The domiciliation of triatomines is one of the main factors increasing the occurrence risk of human cases of this disease. There are 66 species of triatomine in Brazil, with three genera of significant epidemiological importance: Panstrongylus, Rhodnius, and Triatoma. Among the Triatoma species, Triatoma williami, a wild species, has been reported in the Brazilian states of Goiás, Mato Grosso, and Mato Grosso do Sul. In the city of Barra do Garças, Mato Grosso, the invasion by triatomines has been reported, with T. williami being the most common species. Methods: Triatomine specimens were collected by passive surveillance or by active search by agents combating endemic diseases. After taxonomic identification, a parasitological feces diagnosis was performed to detect the presence of Trypanosoma cruzi. Concerning T. cruzi identification, molecular diagnosis and genetic sequencing were performed to identify the strain, also called discrete typing units (DTUs). Results: In 2019, several triatomine specimens were collected in the urban area of Barra do Garças, Mato Grosso. Among them, 155 specimens were T. williami, P. geniculatus, and R. neglectus. In 2020, the sampled triatomine specimens were 56 T. williami, Panstrongylus diasi, and R. neglectus. For these years, T. williami has been the most frequent species. Between 2019 and 2020, 137 T. williami were collected (61% of them inside houses). In two triatomine colonies were found and morphological analyses, indicated were T. williami. These insects were collected inside houses in an urban area, on a neighborhood from Jardim Pitaluga (15°51’57.7” N, 052°16’04.5E). The records were sampled in September/2019 and January/2021. The rate of natural infection was 30.3% and 73.5% for 2019 to 2020. Two T. williami specimens belonging to one of colonies were positive for T. cruzi strain DTU IV, Conclusions: This is the first time that the occurrence of domiciliation of T. williami has been confirmed in an urban area of Barra do Garças, Mato Grosso, Brazil. Further studies are needed for a clearer understanding of the ecology of this species for prevention and control mechanisms, since its sampled specimens had a high rate of natural infection by T. cruzi.