Evaluation ofinfection and exposure in free-roaming cat populations in northern California and southern Texas.

Abstract

OBJECTIVES: Leptospirosis is a re-emergent zoonotic bacterial disease associated with renal and hepatic injury. In free-roaming cats in some regions, a high prevalence ofantibodies has been identified, and pathogenic leptospires have been detected in renal tissue, indicating that they may play a role inepidemiology. The objective of this study was to determine the prevalence ofseroreactivity and urinary shedding ofDNA in free-roaming cats from northern California and southern Texas. A secondary objective was to compare the results of a point-of-care (POC) assay, designed to detectantibodies, with the results of the microscopic agglutination test (MAT) when applied to serum samples from feral cats. METHODS: Specimens were obtained from free-roaming cats from northern California (n = 52; 2020) and southern Texas (n = 75; 2017).quantitative PCR was performed on blood and urine specimens from Californian cats. Serum samples from Californian and Texan cats were subjected to MAT to categorize them asantibody-positive or antibody-negative. The performance of the POC assay was assessed using the MAT as the gold standard. RESULTS: DNA was not detected in the blood or urine of any cats tested. The results of the MAT were positive in 17.3% (n = 9) of Californian cats and 10.7% (n = 8) of Texan cats ( = 0.3). The median MAT titer was 1:100 (range 1:100-1:200) in Californian cats and 1:200 (range 1:100-1:800) in Texan cats. The POC assay was negative in all specimens. CONCLUSIONS AND RELEVANCE: Free-roaming cats in California and Texas are exposed tospecies and may have the potential to act as sentinel hosts. No cats had evidence of current infection, as determined using PCR on blood and urine specimens. The POC test did not reliably detect anti-antibodies in these cats. The role of cats in the maintenance or shedding of pathogenic leptospires requires further investigation.