Evidence of ongoing <i>Trypanosoma cruzi</i> transmission in a low-infestation area of eastern Bolivia

Abstract

ABSTRACT Chagas disease remains a major public health concern in Latin America, with Bolivia reporting one of the highest burdens of infection. While congenital transmission has become the predominant route of new infections in several countries, vectorial transmission persists in rural and peri-urban regions. Postrervalle, in the department of Santa Cruz, is officially classified as a low-infestation area; however, updated community-level data remain limited. Methods We conducted a cross-sectional study in July 2023 involving 58 mothers and 104 of their children in Postrervalle. Participants underwent serological screening using three diagnostic assays, and epidemiological data were obtained through structured maternal questionnaires. Logistic regression models were used to assess associations between child Trypanosoma cruzi seropositivity and maternal or household exposures during pregnancy. Results Seroprevalence was 15.5% among mothers and 3.8% among children. Notably, all seropositive children were born to mothers who tested seronegative, suggesting non-congenital transmission. In multivariable analysis, living in houses with mud walls during pregnancy was strongly associated with child seropositivity (adjusted OR = 225.44), while older child age also increased the odds of infection. Other maternal exposure variables showed elevated but imprecise associations. Conclusion Despite its classification as a low-infestation area, Postrervalle shows evidence of ongoing transmission of T. cruzi linked to domestic structural conditions that facilitate triatomine colonization. These findings highlight the importance of integrating entomological surveillance with household-level risk assessments to better characterize and prevent Chagas transmission in rural communities. AUTHORS’ SUMMARY Chagas disease is caused by the parasite Trypanosoma cruzi and is mostly spread by insects known as “kissing bugs,” which can live in the cracks of walls and roofs in some homes. Although several Latin American countries have reduced transmission through long-term vector control programs, Chagas disease continues to affect many rural and peri-urban communities in Bolivia. Postrervalle, where this study was carried out, is officially classified as a low-risk area, and little recent information exists about local transmission patterns. We screened mothers and their children for Chagas disease and asked the mothers about their living conditions and past exposure to kissing bugs. We found that none of the infected children had mothers who were infected, which suggests that these children did not acquire the disease during pregnancy. Instead, they were likely infected after birth through contact with infected insects in their homes. We also found that children who lived in houses with mud walls were more likely to be infected, indicating that certain types of housing may make it easier for kissing bugs to enter or hide inside homes. These findings show that Chagas transmission can still occur in places thought to be low-risk. Strengthening vector surveillance and improving housing conditions could help reduce infections in similar communities.