Trypanosoma cruzi in wild mammals from an endemic area of Chagas disease on the coast of Ecuador

Abstract

Trypanosoma cruzi is a protozoan parasite that causes Chagas disease, endemic in Ecuador. In the province of Los Ríos, where the vector Triatoma dimidiata is present, vector-borne transmission is considered the primary route of infection. Many mammalian are involved in the transmission cycle of T. cruzi. Nonetheless, significant gaps remain regarding mammalian reservoirs along the Ecuadorian coast, especially in ecologically altered areas. To investigate the role of wild and domestic mammals as hosts, we assessed the presence of T. cruzi in two localities of Quevedo canton. Sampling focused on wild, domestic, and peridomestic mammals using live capture techniques such as mist nets for bats and Sherman and Tomahawk traps for terrestrial mammals. Blood samples were collected from all individuals, and DNA was extracted using a commercial kit. PCR was performed targeting three regions of the T. cruzi genome. In total, 383 mammals were sampled: 66 domestic animals, 6 peridomestic, and 317 wild individuals. Of the wild mammals, 216 were captured in La Virginia 2 and 95 in the Jacome Forest. Four wild individuals tested positive for T. cruzi, including three Glossophaga soricina and one Marmosa simonsi, all collected from La Virginia 2, a peri-urban community. None of the domestic or peridomestic animals were infected. This study reports, for the first time, the infection of M. simonsi with T. cruzi. The presence of positive cases exclusively in an area close to human settlements raises concern about the risk of parasite transmission in transitional landscapes. Transmission cycles of the parasite are known to be influenced by land-use change, deforestation, and host community composition. These factors may alter ecological interactions between vectors and hosts, potentially favoring transmission. Further research is needed in Ecuador to understand how ecosystem alterations shape the sylvatic cycle of T. cruzi, particularly the role of bats in disease maintenance.

Keywords: Chiroptera; Didelphidae; Hosts dynamics.

Graphical abstract

Fig. 1

Study Area in Los Ríos Province (A), showing the location of surveyed households in the La Virginia 2 Community and Jacome Forest localities, near Quevedo City.

Fig. 2

Species accumulation curves for Jacome forest (BJ) and La Virginia community (CV) based on rarefaction of sampling days and captures at each site.

Fig. 3

Agarose gel electrophoresis 2 % for the amplified satellite DNA fragment from T. cruzi kinetoplastid. M: 100bp Opti-DNA Ladder, 1: Marmosa simonsi positive sample, 2–4: Glossophaga soricina positive samples, 5: Negative control (no template). A single 166 bp band (indicated) was observed in all the cases.