Leptospira spp. in Cats in Estonia: Seroprevalence and Risk Factors for Seropositivity

Leptospirosis is a zoonotic bacterial disease that affects humans and animals worldwide. Recently, more attention has been paid to Leptospira spp. infections in domestic cats. In this seroepidemiological study, we estimated the prevalence of anti-Leptospira spp. antibodies in domestic cats in Estonia and evaluated risk factors for the seropositivity. A total of 546 surplus feline plasma and serum samples, collected in collaboration with small animal clinics and an animal shelter in 2013 and 2015, were included in this study. The samples were tested for antibodies against Leptospira spp. using a microscopic agglutination test. The panel included Leptospira interrogans serovars Pomona, Icterohaemorrhagiae, Bratislava, Canicola, and Hardjo, and Leptospira kirschneri serovar Grippotyphosa. Titers ≥100 (positive reactions at dilutions ≥1/100) were considered positive. Anti-Leptospira spp. antibodies were detected in 12.8% of the cats. The percentage of cats that tested positive for antibodies against L. interrogans serovars Pomona, Icterohaemorrhagiae, Bratislava, Canicola, and Hardjo were 9.3%, 3.5%, 2.4%, 0.4%, and 0.2%, respectively, and the percentage of cats that tested positive for antibodies against L. kirschneri serovar Grippotyphosa was 7.3%. Of the seropositive cats, 46.5%, 35.2%, 12.7%, 4.2%, and 1.4% tested positive for 1, 2, 3, 4, and 5 serovars, respectively. The prevalence of anti-Leptospira spp. antibodies was 11.2% in pet cats and 16.3% in shelter cats. Among pet cats, the seroprevalence was over four times higher in cats that had access to the outdoors (17.2%) than in indoor cats (3.9%). Multivariable models, one based on data on pet cats only and another including also data on shelter cats, identified having access to the outdoors, being a shelter cat, and being from Western Estonia as the risk factors for seropositivity. Cats could be better protected from exposure to Leptospira spp. by not allowing them to roam freely outdoors.