Epidemiological Situation of the Exposure to Agents Causing Equine Piroplasmosis in Spanish Purebred Horses in Spain: Seroprevalence and Associated Risk Factors

Equine piroplasmosis (EP) is a tick-borne disease caused by Babesia caballi and Theileria equi, which causes severe economic losses to the equine industry, represented by the Spanish Purebred (SP) horse in Spain. The seroprevalence of EP is known in certain regions of Spain, but till date, there are no data in SP horses. The aim of this study was to determine the seroprevalence of EP in the SP breeding horse population in central Spain and to evaluate risk factors associated with the occurrence of the infection. A total of 536 horse serum samples were tested for antibodies against T. equi and B. caballi by competitive inhibition enzyme-linked immunosorbent assay. Data on possible risk factors were examined using two logistic regression models with and without a random effect at the stud farm level. The true seroprevalence results were 21.8% for T. equi and 4.7% for B. caballi. Increasing horse age and increasing numbers of breeding stallions on the stud farm were identified as factors associated with EP seropositivity. The implementation of vaccination programs in the horses and disinfection measures in the premises were associated with a lower T. equi and B. caballi seroprevalence, respectively. A moderate exposure to EP was found in SP horses in central Spain. Further investigations are necessary to ensure appropriate preventive measures for stud farms and to facilitate the development of an EP surveillance program in the SP breeding horse population.