Assessment of Trypanosoma cruzi Infection Status in White-Eared Opossums (Didelphis albiventris) of the Metropolitan Area of Mendoza, Argentina.

Marsupials of the genus Didelphis are important wild hosts of Trypanosoma cruzi, the causative agent of Chagas disease. They exhibit infection patterns influenced by parasite lineage, as well as distinctive immune responses. We herein assessed the infection status of white-eared opossums (Didelphis albiventris) in the Metropolitan Area of Mendoza (MAM), Argentina, by integrating parasitologic data and serologic responses to T. cruzi antigens (crude homogenates and recombinant proteins) with physiologic and ecologic parameters of the animals. We captured 33 opossums between 2018 and 2021. High infection rates were detected, with 64% (21/33) seropositive by homogenate-based ELISA and 48% (10/21) positivity by quantitative PCR (qPCR). Parasite loads ranged from <0.001 to 40.98 parasite-equivalents/mL, and infected animals were detected in both peri-urban and rural sites. Animals that were qPCR-positive, seronegative occurred exclusively in peri-urban areas, suggesting acute, active infections, whereas seropositive, qPCR-negative individuals generally exhibited good or regular body condition, consistent with chronic or controlled infections. Hierarchical clustering of the reactivity of seropositive animals to recombinant T. cruzi antigens (Ag1 and trypomastigote small surface antigen isoforms) enabled three distinct serologic profiles to be identified. These profiles were associated with different physiologic and ecologic features and were therefore probably caused by infection with different T. cruzi genotypes. Overall, these findings highlight the complex epidemiologic role of D. albiventris in T. cruzi transmission in the MAM and support antigen-specific serology as a useful tool to infer infection dynamics and parasite diversity in epidemiologic studies.