Retrospective evaluation of factors associated with the risk of seropositivity to Ehrlichia risticii in horses in New York State.

This research focuses on identifying the factors associated with the susceptibility of horses in New York state to equine monocytic ehrlichiosis, a bacterial illness, by analyzing historical data from 1985 to 1986. The study found that breed, gender, age, and the period of testing significantly influenced the risk of disease exposure.

Objective of the Research

• The primary goal of this study was to understand the distribution of equine monocytic ehrlichiosis, a disease caused by the bacteria Ehrlichia risticii, among the horse population in New York State.
• The researchers were interested in spotting factors linked with the disease’s risk and used retrospective data from serum samples taken in the years 1985 and 1986.

Methodology

• The researchers examined serum samples at the university’s diagnostic laboratory using an indirect fluorescent antibody technique to detect Ehrlichia risticii antibodies.
• The factors evaluated included the geographic origin and date of the sample submission, the horse’s sex, age, and breed.
• A method known as logistic regression analysis was used to discern any significant factors associated with the risk of E risticii seropositivity while controlling for other factors.

Key Findings

• Out of the 2,579 tested samples, 1,950 (76%) resulted positive.
• The breed of the horse played a significant role, with Thoroughbreds being three times more likely to have been exposed to E risticii than non-Standardbred and non-Thoroughbred breeds.
• Female horses were 2.7 times more likely to have been exposed to the bacteria in comparison to male horses.
• Age also factored into the chances of exposure with the risk increasing as horses aged, peaking at around 12 years, then decreasing afterward.
• The month of submission of the sample also influenced the results. Horses tested in November and December had the highest chances of seropositivity with an odds ratio of 2.1. Those tested between March and April were least likely to be seropositive with an odds ratio of 0.5 when compared to those tested in January and February.