Integrative diagnostic and pathophysiological characterization of canine Chagas disease using sCha peptide and Trypanosoma cruzi lysate antigens.

Abstract

Canine Trypanosoma cruzi infection plays a major role in parasite circulation in human environments. Although several serological tests have been proposed to diagnose Chagas disease, the immune response of dogs to T. cruzi remains poorly characterized, making it difficult to evaluate diagnostic sensitivity, particularly during the chronic phase. Furthermore, reliable markers for disease progression in dogs are lacking, hindering diagnosis and follow-up in endemic regions. This study evaluated a diagnostic approach combining sCha, a recombinant antigen previously validated in humans, with a crude lysate of antigenically diverse T. cruzi strains to discriminate acute and chronic infections and to correlate seropositivity with PCR results and spatial case distribution among owned dogs in metropolitan Caracas. Using a stringent criterion (positivity in both tests), 67.7% of animals were seropositive and 27.3% PCR positive. PCR-positive cases were predominantly observed in dogs younger than two years, and both seropositive and PCR-positive dogs were spatially clustered near El Ávila National Park, independently of housing type. Atrioventricular block and chamber dilation were the earliest cardiac alterations in seropositive animals. IgM and IgG responses against both antigens discriminated against acute and chronic phases, respectively, while only sCha-based serology differentiated dogs with elevated CK-MB levels. These findings support the use of sCha- and lysate-based ELISAs as a practical diagnostic tool for clinicians in endemic areas, integrating epidemiological and pathophysiological criteria for canine Chagas disease assessment.