Leptospirosis is a zoonosis of public health concern in Thailand. Human leptospirosis presents severe illness and can be fatal due to pulmonary hemorrhage, kidney failure, or cardiac impairment. Infected animals show no clinical signs and play an important role in the Leptospira infection of humans and other hosts. The prevalence of leptospirosis in stray animals in Thailand is unknown. The aim of this study was to investigate the incidence of Leptospira infection in stray animals including dogs and cats in Songkhla province, Thailand. A total of 434 blood samples were collected from 370 stray dogs and 64 stray cats during a population control program from 2014 to 2018. Screening the serum samples using the latex agglutination test to detect antibodies against Leptospira interrogans showed that 29.26% (127/434) were positive. There were 120 positive samples for stray dogs and 7 positive samples for stray cats. The detection of positive samples by polymerase chain reaction specific to the LipL32 of L. interrogans showed 1.61% (7/434) were positive. Stray cats (5/64) showed a higher prevalence than stray dogs (2/370), which might be because they are more likely to come into contact with rodents in their habitat. Although the active infection detected was low, the seroprevalence was high. This result indicated that the stray animals might not have been infected at the time of sample collection, but that they had been infected in the past or were in a latent period of infection. Therefore, they might serve as a leptospirosis reservoir for domestic animals and humans present in the same environment. The results show that stray animals need health care, such as vaccination, surveillance, and treatment, when infected to prevent or reduce the risk of transmission to humans.
Keywords: Thailand; investigation; risk reduction; stray animals.