Seroprevalence of Leptospira spp., Toxoplasma gondii, and Dirofilaria immitis in Free-Roaming Cats in Iowa

By the nature of their environment and behavior, free-roaming cats are at increased risk of exposure to a wide range of pathogens compared with client-owned cats. Consequently, free-roaming cats can act as a reservoir for possible zoonotic infections. In this study, 140 cats were prospectively recruited over a 12-month period from a free-roaming cat spay and neuter clinic and a local animal shelter in the state of Iowa. The presence of antileptospiral antibodies was measured using a microscopic agglutination test against six leptospiral serovars (canicola, pomona, icterhemorrhagiae, bratislava, hardjo, and grippotyphosa). In addition, serum samples were tested for the presence of antibodies against Toxoplasma gondii and Dirofilaria immitis using an ELISA and lateral flow immunoassay, respectively. Serum samples from 12/139 cats (8.6%) were positive for the leptospiral serovars tested, with bratislava having the highest prevalence. Cats were more likely to be positive in the spring than in the fall or summer. Positive titers to T. gondii and D. immitis were present in 42/140 cats (30%) and 9/140 cats (6.4%), respectively. Cats >72 months of age were more likely to be seropositive to T. gondii than cats in younger age groups. Feline Leptospira spp. seroprevalence was higher in this Midwestern location than has previously been reported elsewhere in the United States. Contrary to previously reported seasonal trends, this population was more likely to be Leptospira spp. seropositive in the spring rather than fall or summer. Seroprevalence of D. immitis in this geographical location was substantially lower than previous reports of free-roaming cats in the United States.