A liver pathogen closely related to the hepatitis C virus that infects humans was detected in the blood of 6.3 percent of the horses included in a French study.
The recently identified equine hepacivirus (NPHV) is the subject of growing international interest among scientists because horses can naturally eliminate the virus from their system on their own.
Research into how horses manage to do this has the potential to ultimately benefit humans. Hepatitis C virus causes liver disease in an estimated 2.7 to 3.9 million people in the United States alone. The virus affects about 146 million people worldwide.
Until recently, few cases of equine hepacivirus infection had been reported in horses because the virus cannot be detected without blood work.
French researchers set out to learn more about the prevalence and distribution of the virus in France.
Blood samples from 1033 horses from stud farms throughout France were analysed for molecular evidence of the virus. Serum concentrations of biliary acids, glutamate dehydrogenase and L-gamma-glutamyl transferase were also measured for most horses.
Stephane Pronost and her colleagues, writing in the journal Transboundary and Emerging Diseases, said they detected equine hepacivirus in the blood of 6.2% of the horses. Its prevalence reached 8.3% in thoroughbreds − significantly higher than in other breeds.
The presence of circulating virus was not significantly associated with biological problems nor with clinical liver impairment in the horses, they said.
Their analysis work showed that, like almost everywhere else in the world so far, two major groups of equine hepacivirus strains infected French domestic horses.
Based on genetic distances, the study team proposed a classification into two separate subtypes.
Viral loads in the serum of horses infected by the main subtype were, on average, four times higher than in those infected by the second subtype, they reported.
Research around the globe has shown that equine hepacivirus is prevalent in horses, with studies revealing seropositivity in 30% to 40% of those tested, with 3% carrying the virus in their blood.
Further research has shown that adult horses can clear the virus within two months after acute infection, although persistently infected horses have also been identified.
Pronost, S., Hue, E., Fortier, C., Foursin, M., Fortier, G., Desbrosse, F., Rey, F. A., Pitel, P.-H., Richard, E. and Saunier, B. (2016), Prevalence of Equine Hepacivirus Infections in France and Evidence for Two Viral Subtypes Circulating Worldwide. Transbound Emerg Dis. doi:10.1111/tbed.12587
The abstract can be read here.