Nationwide seroprevalence of canine vector-borne pathogens in dogs in Spain

Canine vector-borne diseases (CVBDs) are a health risk for both dogs and humans. This nationwide study sought to determine the seropositivity of Leishmania infantum and Ehrlichia canis and the positivity of Dirofilaria immitis, the main vector-borne pathogens prevalent in Europe, in apparently healthy dogs from Spain. Possible associations between seropositivity/positivity and epidemiological variables were also assessed, respectively.

In a survey conducted in all Spanish 50 provinces, 11,886 dogs from 609 veterinary clinics were tested using the URANOvet® diagnostic rapid test to detect D. immitis antigen, and antibodies against L. infantum and E. canis. Data were collected regarding sex, age, habitat, clinical signs compatible with each pathogen and the regular use of ectoparasiticides.

The overall seropositivity was 17.3% (1915/11,048) for L. infantum, and 3.4% (315/9,125) for E. canis. Positivity for D. immitis was 3.2% (314/9,938). A considerable proportion of infected dogs showed no clinical signs, representing 17.7% of L. infantum, 64.1% of D. immitis, and 35.9% of E. canis positive cases. Significant differences in the epidemiological variables examined (P < 0.05) were related to seropositivy/positivity for the three pathogens examined, including geographic location, habitat, associated clinical signs and use of ectoparasiticides. While a higher seropositivity of L. infantum and positivity for D. immitis antigen were recorded in older dogs (P < 0.001), male dogs showed a higher seropositivity of L. infantum (P < 0.001).

These data suggest that dogs in Spain are consistently exposed to all three vector-borne pathogens analysed. Veterinarians should include these CVBDs in their differential diagnoses and encourage the use of repellents and other prophylactic measures to prevent their transmission by arthropod vectors, considering regional epidemiological risk and lifestyle. Our findings also highlight the need for early detection by routine screening of clinically healthy dogs, as they could be important subclinical carriers.