Assessment of monthly infection risk of heartworm infection in Colombia: integrative ecological niche modeling of Culex quinquefasciatus and Dirofilaria immitis

Heartworm disease ( Dirofilaria immitis ) is a globally distributed vector-borne zoonosis affecting canids and felids, which can be fatal by compromising the cardiorespiratory system. This study analyzes the annual and monthly infection risk in Colombia by integrating ecological niche modeling for Culex quinquefasciatus —the most important and widely distributed vector in the country—with the temperature-dependent number of D. immitis generations within the vector. Results identified the human footprint (78%) as the primary determinant of vector distribution, surpassing climatic variables and confirming the synanthropic nature of transmission. The monthly analysis revealed sustained potential transmission year-round in lowlands and coastal areas, contrasting with a marked thermal barrier in the Andean region, where altitude limits parasite development despite the presence of the vector. External validation confirmed the model's robustness, locating 84.68% of reported cases within very high-risk zones. Heartworm infection in Colombia is a non-seasonal urban phenomenon, strictly modulated by altitude. These findings call for replacing seasonal prophylaxis with continuous preventive protocols and prioritizing epidemiological surveillance under a One Health approach along the country's main demographic corridors. • Heartworm infection risk is continuous year-round in Colombia. • Human footprint, water bodies, and temperature drive infection risk. • Altitude acts as a strict physiological barrier for D. immitis development in the Andes. • Prevention of heartworm transmission should be continuous, not seasonal.