Seroprevalence of selected vector-borne agents in pet cats using the SNAP® 4Dx® PLUS, United States, 2022-2025

Tick-borne diseases predominate among vector-borne diseases of human and veterinary importance in the United States (US). Many of the most important tick-borne agents in people, including Borrelia burgdorferi, Anaplasma spp., and Ehrlichia spp. are zoonoses capable of infecting domestic pets. These infections can impact animal health with widely varying severity, ranging from subclinical to life-threatening disease. Serological testing is essential for screening and diagnosis of these infections in pets, as well as for epidemiological investigations. While vast amounts of data are available on the seroprevalence of antibodies to B. burgdorferi, Anaplasma spp., and Ehrlichia spp. in domestic dogs, comparatively little data is available in domestic cats. The purpose of this study was to evaluate the prevalence of antibodies to B. burgdorferi, Anaplasma spp., and Ehrlichia spp., as well as antigen of D. immitis, the causative agent of heartworm disease, in a population of apparently healthy pet cats from across the US using the point-of-care (POC) SNAP® 4Dx® PLUS test. This POC test does not visually distinguish between antibodies within the Anaplasma genus and antibodies within the Ehrlichia genus. To address this, additional specific peptide testing was conducted at IDEXX Laboratories for Anaplasma spp. and Ehrlichia spp. seropositive samples. In total, n = 1572 feline serum samples were tested using the SNAP® 4Dx® PLUS. All US states were represented by at least 3 samples, and 2.6 % of cats demonstrated evidence of exposure to ≥1 vector-borne pathogen. Cats in the present study were most commonly exposed to Anaplasma spp. (1.40 %), which contrasts previous seroprevalence reports in cats, in which B. burgdorferi predominates. Seroprevalence of Anaplasma spp. was followed by B. burgdorferi (1.15 %), Ehrlichia spp. (0.38 %), and lastly D. immitis antigen detection (0.13 %). Feline exposure to tick-borne agents observed in the present study was compared with canine seroprevalence reported by the Companion Animal Parasite Council over the same time period. We found that feline exposure was 14-28 % of the exposure prevalence reported in dogs. Although less common than canine infection, continued investigation into feline infection with B. burgdorferi, Anaplasma spp., and Ehrlichia spp. is warranted. Feline susceptibility to these agents, transmission dynamics, pathogenicity, and immunologic response remain poorly described.