Seroprevalence and infection rates for equine orbivirus infections in dogs at Onderstepoort, South Africa

Abstract

Recent case reports have suggested an increase in cases where dogs have been affected by African horse sickness virus (AHSV). Contrary to historic findings, several cases have been reported where dogs became infected without any evidence of contact with or consumption of infected horses or their products. This was a prospective study to determine the prevalence of specific antibody and nucleic acid to AHSV and Equine encephalosis virus (EEV) in a high risk, isolated dog population during the high vector period in an endemic area. Dogs were kept in open kennels in close proximity to horses, sheep and cattle. Dogs in this population have historically been diagnosed with clinical AHS. Blood samples were collected on a monthly interval from February to June 2019. Antibody to AHSV was detected using an indirect ELISA while antibody to EEV was detected using a competitive ELISA. Infection rates were determined by demonstrating viral nucleic acids by RTqPCR. All of the 37 sampled dogs remained negative for RNA to both AHSV and EEV for the duration of the study. This indicates that there were no equine orbiviruses circulating in this dog population and is consistent with the absence of any clinical signs during the study period. This is also in line with the absence of any new AHS case reports in dogs from the area. Low levels of antibody were detected at some time points indicating transient exposure without viremia or due to crossreactions with unknown antigens.