Hepatitis-associated virus infections in Austrian equids: A survey of equids sampled across Austria

This study aimed to determine the (sero)prevalence of equine hepacivirus (EqHV), equine parvovirus-hepatitis (EqPV-H), equid hepatitis B virus (EqHBV) and hepatitis E virus (HEV), in equids across Austria and to identify associated risk factors. In a cross-sectional study conducted between May 2023 and August 2024, 586 equids (583 horses and three donkeys) were sampled. Serum samples were analysed for EqHV RNA, EqPV-H DNA, and EqHBV DNA via qPCR/RT-qPCR and for antibodies against EqHV and EqPV-H via luciferase immunoprecipitation system. Faecal samples were tested for HEV RNA via RT-qPCR, and sera were screened for HEV antibodies via ELISA. Risk factors were assessed via multivariable logistic regression with generalized estimating equations. Nucleic acid prevalence for EqHV and EqPV-H accounted each for less than 3% of the sampled animals, whereas the seroprevalence was higher: 36.9% for EqHV and 31.4% for EqPV-H. Neither EqHBV nor HEV nucleic acids were detected; one horse was HEV-seropositive. Equine hepacivirus seropositivity was significantly associated with season (spring, winter), cough and concurrent EqPV-H seropositivity. For EqPV-H, seropositivity showed significant association with younger age (1-3 years), season (winter), specific regions, EqPV-H viraemia and concurrent EqHV seropositivity. This survey confirms that EqHV and EqPV-H are endemic in Austrian equids, with low viraemia but widespread seropositivity. The absence of active EqHBV and HEV infections indicates negligible risk. The findings highlight the need for longitudinal studies to elucidate transmission pathways and investigate the clinical significance of persistent infections with EqHV and EqPV-H.