Seroprevalence of West Nile fever virus in horses in the Belgrade epizootiological area

West Nile fever is a vector borne viral disease that can affect humans, horses, birds and sometimes other species of animals. Every year West Nile fever is detected in the human population in Serbia. The disease often occurs in a subclinical form, but most clinically evident cases occur in horses. Therefore, horses are recommended as a sentinel species for monitoring the general incidence of West Nile fever in a specific territory. Our goal was to determine the prevalence of antibodies against West Nile fever virus in horses in the Belgrade epizootiological area. We examined serum samples from 77 horses to determine the seroprevalence of West Nile fever virus in horses throughout the city of Belgrade. Sera were tested by commercial ELISA tests for detection of specific IgG-class antibodies to West Nile fever virus and for the detection of specific IgM-class antibodies to confirm the presence of old and acute (recent) infections in horses. The results confirmed that West Nile fever virus is widespread, detected in 70.1% of the surveyed horse population in Belgrade, and we also detected 5.1% of acute cases had occurred due to horses being infected in 2019. The seroprevalence of West Nile virus in the horse population in the municipality of Belgrade is increasing.