Serosurvey of Babesia canis, Babesia gibsoni and Ehrlichia canis in pound dogs in California, USA

The seroprevalence of three canine tick-transmitted parasites, Babesia gibsoni, Babesia canis and Ehrlichia canis, was estimated in selected regions of California. Blood smears and sera were obtained from 971 dogs in seven animal shelters: four in Los Angeles County, one in Yolo County, one in El Dorado County in California and one in Minden, Nevada. Seroprevalence in Los Angeles County shelters were 0–13%, 0–2.6% and 0% for B. canis, B. gibsoni and E. canis, respectively. Seroprevalences of the same three parasites in Yolo County and El Dorado County Shelters were 0% except for a 1% seroprevalence of B. canis in dogs from Yolo County Shelter.

Potential risk factors (breed, age, sex and evidence of ticks on the dogs) for B. canis seropositivity were evaluated. Dogs 3 years of age or older had a significantly higher risk (odds ratio 5.04) of being seropositive to B. canis compared with dogs less than 1 year old. Breed, sex and evidence of ticks were not associated with seropositive reactions to B. canis. Of 29 coyotes captured in Los Angeles County, three (10.3%) were seropositive for B. gibsoni, with titers of 1280 to 2560. This study indicated that dogs in Los Angeles County were at higher risk of being seropositive and potentially infected with canine babesial parasites than dogs in Yolo and El Dorado Counties. Movement of chronically infected dogs from Los Angeles County into other areas could contribute to the spread of these important pathogens.