Carrier Status ofLeptospiraspp. in Healthy Companion Dogs in Sri Lanka

Abstract

Dogs are asymptomatic chronic carriers of Leptospira spp. and excrete these bacteria in their urine, resulting in environmental contamination and potentially leading to zoonotic transmission. Although a previous study in Sri Lanka detected anti-Leptospira antibodies in companion dogs, the urinary shedding of Leptospira spp. and the Leptospira species and serogroups prevalent in them remain unclear. Thus, the current study identified the prevalent Leptospira serogroups and the carrier status of Leptospira spp. in apparently healthy, client-owned dogs in the Kandy District of Sri Lanka. Serum and urine samples were collected from 96 unvaccinated and 82 vaccinated dogs. Anti-Leptospira antibodies and Leptospira DNA in urine were detected using the microscopic agglutination test (MAT) and nested PCR that targeted the pathogenic leptospiral gene, flaB. The flaB sequences were compared with those of Leptospira spp. using the public databases. MAT detected anti-leptospiral antibodies in 15.6% (15/96) of the unvaccinated dogs, and the reactive serogroups were observed to be Sejroe (11.5%), Canicola (2.1%), Icterohemorrhagiae (1.0%), and Javanica (1.0%). Furthermore, MAT results revealed that 11.0% (9/82) of the vaccinated dogs tested positive for the anti leptospira antibodies and the only reactive serogroup was Sejroe. Leptospira DNA was detected in 15.6% (15/96) and 15.9% (13/82) of urine samples collected from unvaccinated and vaccinated dogs, respectively, and phylogenetic analysis revealed that the animals were infected with L. borgpetersenii, L. interrogans, L. kmetyi, and L. weilii. The L. interrogans sequence detected in the canine sample was identical to the one that was previously reported in a human sample from the Kandy District. This study demonstrated that both unvaccinated and vaccinated dogs excrete various pathogenic Leptospira spp. in their urine, suggesting that they may play an important role in environmental contamination that poses a health risk to the dog owners and the general public.