Triatoma dimidiata, domestic animals and acute Chagas disease: A 10 year follow-up after an eco-bio-social intervention

Abstract

Introduction: Trypanosoma cruzi, the causative agent of Chagas disease, is primarily transmitted by triatomine insects, including Triatoma dimidiata. In Central America, vector control programs have significantly reduced transmission; however, certain regions, such as Comapa, Jutiapa, Guatemala, continue to experience persistent T. dimidiata infestation. This study presents a 10-year follow-up assessment of triatomine infestation, T. cruzi infection, and acute Chagas disease cases after an eco-bio-social intervention.

Methods: Between June and August 2022, entomological surveys were conducted in four communities of Comapa. Seventy six households were systematically searched for triatomines using the one-person hour method, which were collected and processed for T. cruzi detection using qPCR. Bloodmeal analysis was performed to assess host feeding patterns. Dog samples and environmental DNA from household surfaces were also processed for T. cruzi detection. Additionally, surveillance for acute Chagas disease cases was carried out in collaboration with the Ministry of Health.

Results: Persistent infestation of T. dimidiata was observed across all communities, with infestation rates ranging from 17-38% and colonization levels between 9-29%. The mean household triatomine density remained low, suggesting a possible reduction in transmission risk. A total of 86 triatomines were collected, of which 26% tested positive for T. cruzi (all TcI strain). Amplicon deep sequencing analysis from triatomines identified seven vertebrate species and one insect family as hosts upon which triatomines have previously fed, with chickens being the most common blood source (occurring in 57% of triatomines), along with rats, dogs, humans, cats, pigs, ducks, and one genus of cockroach. Of the 132 dogs processed 22% were positive for T. cruzi (all TcI). One acute Chagas disease case detected in a child in 2015 remained seropositive in 2022, emphasizing the need for continued surveillance.

Conclusions: Despite multiple interventions over a decade, T. dimidiata infestation remains high in Comapa with sustained evidence of actue disease in humans, necessitating continued vector control efforts. The persistence of T. cruzi transmission among triatomines and dogs and the predominant role of chickens in supporting the vector population highlights the need for innovative control strategies including those that target domestic animals to mitigate Chagas disease risk.

Keywords: Chagas disease; Follow-up; Triatomines; acute cases; persistent; treatment.

Figure 1.. Triatomine collections sites in Comapa, Jutiapa, Guatemala (2022).

Map was generated using Quantum GIS (QGIS 3.30) using freely available administrative boundaries.

Figure 2.. Triatoma dimidiata bloodmeal analysis in Comapa, Jutiapa, Guatemala (2022).

A) Relative abundance of triatomine domicile and peridomicile collections by life stages and communities. B) Relative abundance of host feeding sources of triatomines by life stages. C) Bloodmeal source for single and double host feeding, with percentage of positive T. cruzi bloodmeals. The size of arrow is proportionate to number of observed bloodmeals from a given host. Figure 2C created with BioRender.