New Parvovirus Associated with Serum Hepatitis in Horses after Inoculation of Common Biological Product

Emerg Infect Dis. 2018 Feb;24(2):303-310. doi: 10.3201/eid2402.171031.


Equine serum hepatitis (i.e., Theiler's disease) is a serious and often life-threatening disease of unknown etiology that affects horses. A horse in Nebraska, USA, with serum hepatitis died 65 days after treatment with equine-origin tetanus antitoxin. We identified an unknown parvovirus in serum and liver of the dead horse and in the administered antitoxin. The equine parvovirus-hepatitis (EqPV-H) shares <50% protein identity with its phylogenetic relatives of the genus Copiparvovirus. Next, we experimentally infected 2 horses using a tetanus antitoxin contaminated with EqPV-H. Viremia developed, the horses seroconverted, and acute hepatitis developed that was confirmed by clinical, biochemical, and histopathologic testing. We also determined that EqPV-H is an endemic infection because, in a cohort of 100 clinically normal adult horses, 13 were viremic and 15 were seropositive. We identified a new virus associated with equine serum hepatitis and confirmed its pathogenicity and transmissibility through contaminated biological products.

Keywords: Theiler’s disease; United States; animal model; biologics; equine liver disease; hepatitis; horse; metagenomics; parvovirus; veterinary virology; viruses.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cardiovirus Infections / veterinary*
  • Cardiovirus Infections / virology
  • Drug Contamination
  • Female
  • Hepatitis, Viral, Animal / virology*
  • Horse Diseases / virology*
  • Horses
  • Parvoviridae Infections / veterinary*
  • Parvoviridae Infections / virology
  • Parvovirinae / genetics
  • Parvovirinae / isolation & purification*
  • Phylogeny
  • Tetanus Antitoxin / adverse effects*
  • Vaccination / adverse effects
  • Viremia


  • Tetanus Antitoxin