MONDAY, May 23 (HealthDay News) -- Researchers report that they've discovered a virus similar to the human hepatitis C virus in dogs, a finding that might provide insight into how the germ evolved in people and perhaps lead to better treatments.
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About 200 million people around the world are thought to suffer from hepatitis C, including an estimated 3.2 million chronically infected people in the United States. Many don't know they're infected with the liver-damaging virus that causes the disease, which means they can spread it to others without realizing it.
The new findings suggest that hepatitis C may have "jumped" from dogs to humans more than five centuries ago, the researchers said.
"Considering the origin of HIV, we expected to find the closest homologs, or genetic relatives, of [hepatitis C virus] in non-human primates," study author Dr. Amit Kapoor, an investigator with Columbia University's Mailman School of Public Health's Center for Infection and Immunity, said in a news release.
"However," Kapoor added, "while we were analyzing samples from dogs involved in outbreaks of respiratory disease, we came upon a virus that was more similar to HCV than other viruses of the same family. So far, we have only detected [the virus] in sick animals, a few of which had died of unknown causes. Because of its close genetic similarity to HCV, we suggested the name of canine hepacivirus."
Study co-author Dr. Charles Rice, scientific and executive director of the Center for the Study of Hepatitis C at The Rockefeller University, said in the news release that the beginnings of hepatitis C "remain a mystery. These findings underscore the need to look beyond primates for clues to the origins."
Scientists say there's no risk of modern-day dogs infecting people with either human hepatitis C or the canine form.
Hepatitis C is a liver disease that's typically spread through contact with infected blood. It can also spread through sex with an infected person and from mother to baby during childbirth, according to the U.S. National Institutes of Health.
The study appears in this week's issue of the Proceedings of the National Academy of Sciences.
-- Randy Dotinga
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SOURCE: PNAS, news release, May 23, 2011