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

Edward R. Atwill From the Section of Epidemiology, Department of Clinical Science (Atwill, Mohammed), and the Diagnostic Laboratory (Dubovi, Lopez), New York State College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Search for other papers by Edward R. Atwill in
Current site
Google Scholar
PubMed
Close
 DVM, MPVM
,
Hussni O. Mohammed From the Section of Epidemiology, Department of Clinical Science (Atwill, Mohammed), and the Diagnostic Laboratory (Dubovi, Lopez), New York State College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Search for other papers by Hussni O. Mohammed in
Current site
Google Scholar
PubMed
Close
 BVSc, PhD
,
E. Dubovi From the Section of Epidemiology, Department of Clinical Science (Atwill, Mohammed), and the Diagnostic Laboratory (Dubovi, Lopez), New York State College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Search for other papers by E. Dubovi in
Current site
Google Scholar
PubMed
Close
 PhD
, and
J. Lopez From the Section of Epidemiology, Department of Clinical Science (Atwill, Mohammed), and the Diagnostic Laboratory (Dubovi, Lopez), New York State College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Search for other papers by J. Lopez in
Current site
Google Scholar
PubMed
Close
 DVM, PhD

Click on author name to view affiliation information

SUMMARY

A retrospective study was designed to determine the distribution of equine monocytic ehrlichiosis among the equine population in New York state, and to identify factors associated with risk of disease. Serum samples submitted to the diagnostic laboratory of the university during the period from January 1985 through December 1986 were examined for antibodies to Ehrlichia risticii, using the indirect fluorescent antibody technique. Factors evaluated included geographic origin and date of submission of the sample, and age, breed, and sex of the horse. Logistic regression analysis was used to identify which factors were significantly associated with the risk of seropositivity to E risticii, while simultaneously controlling for other factors.

Of the 2,579 tested samples, 1,950 (76%) had positive results. Factors significantly associated with risk of seropositivity to E risticii were: breed of the horse (Thoroughbreds were 3 times more likely to have been exposed to E risticii, compared with non-Standardbred, non-Thoroughbred breeds); sex (female horses were 2.7 times more likely to have been exposed, compared with male horses); age of the horse (the risk of being exposed to E risticii increased with age, peaked at around 12 years, and decreased thereafter); and month of submission (horses tested during November and December had the highest odds of being seropositive [odds ratio = 2.1], and horses tested during March through April were least likely to be seropositive [odds ratio = 0.5], compared with horses tested during January and February).

SUMMARY

A retrospective study was designed to determine the distribution of equine monocytic ehrlichiosis among the equine population in New York state, and to identify factors associated with risk of disease. Serum samples submitted to the diagnostic laboratory of the university during the period from January 1985 through December 1986 were examined for antibodies to Ehrlichia risticii, using the indirect fluorescent antibody technique. Factors evaluated included geographic origin and date of submission of the sample, and age, breed, and sex of the horse. Logistic regression analysis was used to identify which factors were significantly associated with the risk of seropositivity to E risticii, while simultaneously controlling for other factors.

Of the 2,579 tested samples, 1,950 (76%) had positive results. Factors significantly associated with risk of seropositivity to E risticii were: breed of the horse (Thoroughbreds were 3 times more likely to have been exposed to E risticii, compared with non-Standardbred, non-Thoroughbred breeds); sex (female horses were 2.7 times more likely to have been exposed, compared with male horses); age of the horse (the risk of being exposed to E risticii increased with age, peaked at around 12 years, and decreased thereafter); and month of submission (horses tested during November and December had the highest odds of being seropositive [odds ratio = 2.1], and horses tested during March through April were least likely to be seropositive [odds ratio = 0.5], compared with horses tested during January and February).

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 74 74 30
PDF Downloads 23 23 2
Advertisement