A new hepatitis virus—once thought to occur only in Asia and Africa—is increasingly showing up among North Americans and Europeans. And this new liver infection poses a serious threat to people already infected with chronic hepatitis B or C.
Recently, researchers are using more refined tools and looking more closely at the prevalence of hepatitis E virus (HEV) infection. A Medscape overview on HEV reports that 21% of U.S. adults screened had signs of resolved HEV infections and a report in this month’s journal of Emerging Infectious Diseases revealed that 17% of blood samples submitted to the U.S. Centers for Disease Control and Prevention between 2005 and 2012 were infected with hepatitis E.
Risk of HEV infection increases with age. Fewer than 10% of children and teens had been infected, compared to 40% of those 60 and older.
Hepatitis E shares some similarities to hepatitis A. It is spread through the fecal-oral route. An infected person or animal sheds the virus through their stool, and it spreads through contaminated drinking water. Doctors used to think that the rare hepatitis E infection that was diagnosed in the United States resulted from international travel to areas with contaminated drinking water—but not any more.
More and more HEV cases are showing up in people who have never traveled and researchers are finding HEV in pork meat and livers, rabbit and other home-grown species, which may be the source for the growing number of infections in North America and Europe.
Recently, a European study found that 15% of Dutch pigs and 7% of Belgium pigs in two slaughterhouses were HEV-infected, and a study published this month reports that 16.5% of farm-raised rabbits in Virginia had HEV in their blood stream. Eating under-cooked pork or rabbit, or contact with water or shellfish contaminated by animal waste clearly poses a risk.
Like hepatitis A, HEV usually causes a short-lived infection with few symptoms. But when pregnant women are infected with HEV, they experience high rates of miscarriages and death especially when in late pregnancy.
In people with chronic hepatitis B or C, another liver infection can be deadly. One study from Brazil found people coinfected with HEV and hepatitis C suffered a high rate of severe liver damage and death.
“HEV infection is an under-diagnosed disease because of the use of low-sensitivity (lab tests),” researchers reported in this month’s journal, Current Opinion in Gastroenterology. They noted researchers are discovering new HEV strains or genotypes that can even cause chronic infections in people with suppressed immune systems.
Currently, pegylated interferon and ribavirin have been found to effectively treat HEV infection. China reportedly has developed a vaccine that prevents HEV infection, but it has not been distributed worldwide.
Christine M. Kukka