Year of Publication

2016

College

Public Health

Degree Name

Master of Public Health (M.P.H.)

Committee Chair

Wayne Sanderson, PhD, MS

Committee Member

Lorie Chesnut, DrPH, MPH

Committee Member

Craig Carter, DVM, PhD, DACVPM, DSNAP

Abstract

BACKGROUND

Leptospirosis is a worldwide zoonotic bacterial disease of significant importance for both human and animal health. There are many sources of infection and shedding of the bacteria, including horses. There is a known occupational hazard for leptospirosis, especially in occupations that work directly with animals or animal products. This study examined the prevalence of equine leptospirosis in Kentucky in relation to trends over time and geographical distribution.

METHODS

Data was obtained from the University of Kentucky Veterinary Diagnostic Laboratory(UKVDL) on equine leptospirosis from 1993 through September 2015. Overall seropositive prevalence and prevalence stratified by serovar were calculated. Furthermore, distribution of positive and negative tests by month, year, and season was depicted graphically. The relationship with season and seroprevalence was further analyzed using chi square and logistic regression. Geographical distribution of prevalence was explored as well as relationship with environmental factors.

RESULTS

Based on samples submitted to the UKVDL, the seroprevalence of equine leptospirosis in the central and bluegrass regions of Kentucky was 12.23%. Leptospira interrogans serovar Grippotyphosa was the most common serovar in these data, followed by serovar Pomona. Positive tests were most common in the winter months of December and January. Fall had the 5 greatest of odds of having a positive test (OR 3.88 [95% CI: 3.54, 4.25]). The highest prevalence of seropositive results in 23 years occurred in 2012. Positive prevalence was geographically limited to five counties, with Woodford County having the highest prevalence based on horse population. Six out of nine farms that had positive results were close in proximity and in the same hydrologic unit.

CONCLUSION

The prevalence of positive leptospirosis has increased over the last 23 years in Kentucky and there is a significant correlation with season. Geographical distribution is focused on four bordering counties. Further research should be done exploring the effect of management practices and environmental exposure on leptospirosis seroprevalence in the equine population in Kentucky.

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