Benefit-cost analysis of vaccination of horses as a strategy to control equine monocytic ehrlichiosis.
OBJECTIVE
To determine whether horses in New York should be vaccinated against equine monocytic ehrlichiosis (EME).


METHODS
Decision-tree analyses of data from a cross-sectional study and a case-control study.


METHODS
Horses in New York.


METHODS
Annual expected monetary loss per horse attributable to EME was calculated for vaccinated and nonvaccinated horses in New York. Because risk of being seropositive was dependent on county in which the horse was located, farm elevation, and use of each horse, decision-tree analyses were stratified by these factors.


RESULTS
Annual expected monetary loss per horse attributable to EME for horses vaccinated by veterinarians ranged from $ 21 to $ 21.83/horse/y; for horses vaccinated by owners ranged from $ 10 to $ 10.83/horse/y; and for nonvaccinated horses ranged from $ 0 to $ 4.03/horse/y. Assuming 78% of vaccinated horses were protected and mean losses associated with EME included costs for horses that died, annual incidence density at which expected monetary loss for vaccinated horses was equal to that for nonvaccinated horses was 12 cases/1,000 horses/y and 25 cases/1,000 horses/y for horses vaccinated by owners or by veterinarians, respectively.


CONCLUSIONS
Annual vaccination minimizes monetary losses attributable to EME only when the annual incidence density exceeds 12 to 25 cases/1,000 horses/y. In New York, expected monetary losses are minimized when horses are not vaccinated because of the low annual incidence density in most regions.
Atwill
E R
ER
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401, USA.
Mohammed
H O
HO
D000818:Animals; D016022:Case-Control Studies; D003362:Cost-Benefit Analysis; D003430:Cross-Sectional Studies; D003663:Decision Trees; D016873:Ehrlichiosis / Q000191:economics / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary*; D006734:Horse Diseases / Q000191:economics / Q000453:epidemiology / Q000517:prevention & control*; D006736:Horses; D009518:New York / Q000453:epidemiology; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014611:Vaccination / Q000191:economics / Q000662:veterinary*