Presence of Dirofilaria immitis in domestic cats and dogs in Chile: Assessment of monthly infection risk as a preventive tool

Dirofilaria immitis is the causative agent of heartworm disease, a cosmopolitan vector-borne zoonotic disease that affects domestic and wild mammalian animals, and can be fatal, affecting the vascular and pulmonary systems, as well as other systems such as the renal system. The aim of this study was to analyze the monthly risk of D. immitis infection in Chile as a disease prevention tool using Ecological Niche Models (ENM), validated with a seroepidemiological study. Vector presence data ( Culex spp. and Aedes spp.) and bioclimatic variables were collected to model habitat suitability using MaxEnt, integrating them with the calculation of potential generations of the parasite. For validation, samples from 323 pets (178 cats and 145 dogs) from north-central Chile were analyzed. The ENM showed excellent predictive capacity (Area Under the Curve, AUC > 0.89), with the human footprint being the variable with the highest contribution. The model showed marked seasonality, with maximum risk in the austral summer (January-February) dropping to near-zero levels in winter due to thermal restrictions and the Andes Mountains barrier. Serological analysis revealed D. immitis prevalence of 12.9% in cats and 5.5% in dogs, reporting the parasite’s circulation in the country. All positive animals were geolocalized in high or very high-risk areas. Projections to 2100 warn of a massive territorial expansion, estimating suitable habitat gains from 62.8% (Shared Socio-economic Pathways, (SSP) scenario SSP1-2.6) to 103.5% (scenario SSP5-8.5) toward the center-south. It is necessary to incorporate the generated dynamic colorimetric maps that alert about the risk of infection into chemoprophylaxis policies and active surveillance in Chile under the One Health approach.