Occurrence of Dirofilaria immitis and tick-borne infections caused by Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato and Ehrlichia canis in domestic dogs in France: results of a countrywide serologic survey.

The occurrence of Dirofilaria immitis antigen and antibodies against tick-borne pathogens in French dogs has been analysed based on 1,050 blood samples. Serum samples of 919 dogs (group A) were sent for a variety of diagnostic investigations, further 131 dogs (group B) were tested for a tentative diagnosis of heartworm disease. All samples were tested for D. immitis antigen. Samples in group A were also tested for specific antibodies against three tick-borne pathogens (Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato and Ehrlichia canis). Results were plotted in geographical maps. Occurrence of D. immitis antigen in group A (0.22%; 95 % CI: 0.03-0.78%) was significantly lower (p < 0.0001) than in group B (6.87%; 95% CI: 3.19-12.64%). Heartworm infections in both groups were regionally restricted to the areas of Bouches-du-Rhône in the South of France and Corsica. In group A, the calculated seroprevalence was 2.72% (95% CI: 1.77-3.99%) for A. phagocytophilum, 1.09% (95% CI: 0.52-1.99%) for B. burgdorferi and 0.33% (95% CI: 0.07-0.95%) for E. canis with a distribution of the positive cases throughout the country. This study represents the first data of A. phagocytophilum seroprevalence in the French dog population.