A One Health Perspective on Heartworm Disease: Allergy Risk in Owners of Infected Dogs in Gran Canaria (Spain)

Heartworm disease, caused by <i>Dirofilaria immitis</i> and transmitted by mosquitoes, represents a major veterinary and zoonotic concern. Beyond its recognized cardiopulmonary effects in dogs, increasing evidence suggests that parasite-derived antigens may contribute to allergic disease in humans. Gran Canaria (Canary Islands, Spain) is a hyperendemic region for heartworm disease, offering a unique setting to explore this potential relationship. Therefore, the aim was to analyze the association between canine infection with <i>D. immitis</i> and the occurrence of allergic conditions in their owners on Gran Canaria. This cross-sectional study included 644 dogs and their respective owners. Dogs were tested for circulating <i>D. immitis</i> antigens using a commercial rapid test. Owners provided information on allergy through medical anamnesis. Associations between canine infection status, animal-related variables (age, sex, breed, habitat), and owner-reported allergies (age, sex) were analyzed using chi-square and Fisher's exact tests with Bonferroni correction. The results showed that 46.4% of dogs tested positive for <i>D. immitis</i> and 43.8% of owners reported allergic diseases. However, 24.64% of dog owners who tested negative for heartworm disease and 65.89% of owners with positive pets reported allergic diseases. In fact, owners of infected dogs exhibited a significantly higher prevalence of allergies compared to those of uninfected dogs. Canine age, sex, breed, and owner demographics were not associated with infection or allergies. However, dog habitat was significantly associated with both outcomes: dogs living indoors had lower infection rates, while owners of infected dogs in mixed indoor-outdoor environments reported the highest rates of allergy. This study provides the first epidemiological evidence of an association between canine heartworm infection and allergies in owners within a hyperendemic European region. The findings suggest that cohabitation with infected dogs may represent a novel risk factor for atopy, reinforcing the importance of integrated preventive measures and highlighting the relevance of a One Health approach.