Sera from employees and horses residing on farms affected (AF) by outbreaks of
leptospirosis in Central Kentucky since 2006 were compared to farms unaffected (UF) by
these outbreaks during this same time period. A total of six farms, three farms from each
group, were compared (4 human subjects and 4 horses) for a total of 24 horses and 24
humans. Sera from a second group, veterinarians specializing in equine medicine (EV), were
also analyzed. This group contained 24 veterinarians with a range of exposure levels from no
known past exposure to individuals exposed five days previous to collection of sera. Each
farm manager completed a survey assessing farm management of horses. In addition,
veterinarians completed a survey regarding their equine medicine experience. Enzyme-linked
immunosorbent assays (ELISA) showed an increased risk of seroconversion to Leptospira in
5 (22%) of 23 equine veterinarians compared to zero (0%) of 24 farm workers (p=0.05).
Antibody levels for both sphingomyelinase 2 (Sph2) and leptospiral immunoglobulin-like
protein A (LigA) were significantly increased (p=0.03 and p=0.05 respectively) in
veterinarians. Indirect hemoagglutination (IHA) and microscopic agglutination (MAT) titers
were negative for all individuals participating in the study. Risk for seroconversion did not
appear to be influenced by the period of time from last exposure nor age of the individual.
There is an increased risk for seroconversion to Leptospira, without the appearance of clinical
disease, in EV compared to individuals working on Central Kentucky horse farms.
