First description of Theiler's disease‐associated virus infection and epidemiological investigation of equine pegivirus and equine hepacivirus coinfection in Brazil

Abstract

Recent advances in the study of equine pegivirus (EPgV), Theiler's disease-associated virus (TDAV) and equine hepacivirus (EqHV) highlight their importance to veterinary and human health. To gain some insight into virus distribution, possible risk factors, presence of liver damage and genetic variability of these viruses in Brazil, we performed a cross-sectional study of EPgV and TDAV infections using a simultaneous detection assay, and assessed EqHV coinfection in different horse cohorts. Of the 500 serum samples screened, TDAV, EPgV and EPgV-EqHV were present in 1.6%, 14.2% and 18.3%, respectively. EPgV-positive horses were present in four Brazilian states: Espírito Santo, Mato Grosso do Sul, Minas Gerais and Rio de Janeiro. Serum biochemical alterations were present in 40.4% of EPgV-infected horses, two of them presenting current liver injury. Chance of infection was 2.7 times higher in horses ≤5 years old (p = 0.0008) and 4.9 times higher in horses raised under intensive production systems (p = 0.0009). EPgV-EqHV coinfection was 75% less likely in horses older than 5 years comparatively to those with ≤5 years old (p = 0.047). TDAV-positive animals were detected in different horse categories without biochemical alteration.

Hepatic Enzyme Profile in Horses

“…Infectious and non-infectious causes of liver and biliary tract inflammation have also been described. These include serum hepatitis or Theiler’s disease or viral hepatitis (caused by equine herpesvirus, hepatitis, equine hepacivirus, and equine parvovirus), parasitic hepatitis (caused by large strongyles and ascarids), Tyzzer’s disease ( Clostridium piliforme ), inflammatory diseases such as cholangiohepatitis (due to cholelithiasis or intestinal obstruction), displacement of the right dorsal colon with bile duct obstruction, cholelithiasis, hepatic torsion, portal vein thrombosis and hyperlipemia [ 8 , 13 , 14 , 15 , 16 , 17 ]. Other causes of liver disease are primary neoplasms such as hepatocellular carcinoma, cholangiocarcinoma, or hepatoblastoma.…”

Equine Parvovirus-Hepatitis in China: Characterization of Its Genetic Diversity and Evidence for Natural Recombination Events Between the Chinese and American Strains

“…TDAV RNA was detected in affected horses and in administered antitoxin samples; therefore, TDAV was considered as the possible agent of equine serum hepatitis. However, this virus has only been observed in Brazilian equines since its first identification (4). EqPV-H was first discovered in a horse that died of equine serum hepatitis in the USA in 2018 (3).…”

No Evidence of Mosquito Involvement in the Transmission of Equine Hepacivirus (Flaviviridae) in an Epidemiological Survey of Austrian Horses

“…Phylogenetic clustering of EqHV isolates from individual horses within their respective herds also suggests a horizontal route of transmission [17]. Young horses subjected to intensive management practices appear to be particularly at risk [18,19]. HCV is known to spread by venereal transmission [20].…”