Detection of Babesia vogeli in stray cats of metropolitan Bangkok, Thailand

The combination of a rapidly growing stray animal population and the lack of animal control in Bangkok has resulted in a unique opportunity to evaluate the potential role of companion animals as sentinels and reservoirs of infectious diseases, including several of those caused by vector-borne parasites. The purpose of this study was to determine the prevalence and factors associated with the distribution of Babesia species infections among stray cats in Bangkok. Blood samples were collected from 1490 stray cats residing in 140 monasteries of 50 metropolitan districts of Bangkok, and assayed with light microscopy and PCR for evidence of Babesia spp. Pear-shaped merozoites were observed microscopically from two (0.13%) of these cats, while a nested 18S rDNA-based PCR assay detected babesial infections in 21 (1.4%) of the cats tested. The prevalence of infection was significantly different between sexes (p < 0.05), and PCR-positive cats were found in 30% (15/50) of the districts surveyed. All 21 amplicon sequences were identical, and were determined to be closest to that reported for B. vogeli (98% identity). These results represent the first molecular confirmation that a Babesia sp. is enzootic among stray cat populations in Thailand, and suggest that the presence of pet companion animals could be a risk factor for exposure of stray cats to vector-borne parasites.