August 31, 2009

Hepatitis E more widespread in U.S. than previously suspected

Exposure to hepatitis E virus appears to be common in the United States, although disease following exposure is rarely reported, according to a study led by researchers at the Johns Hopkins Bloomberg School of Public Health. The study found antibodies indicating exposure to HEV in 21 percent of the U.S. population between 1988 and 1994. HEV is a major cause of viral hepatitis in many developing countries, but how it is spread in developed countries is not fully known. The study is published in the July 1 issue of the Journal of Infectious Diseases.

“Our study shows that animals could play an important role in the spread of HEV in the U.S. Having a dog or pet in the home or consuming meats like liver and other organs were significantly associated with increased odds of exposure to HEV,” said lead author Mark H. Kuniholm, a 2007 graduate of the Bloomberg School of Public Health.

For the study, the research team relied on data from the Third National Health and Nutrition Examination Survey, known as NHANES III, conducted by the National Center for Health Statistics between 1988 and 1994. Blood samples from more than 18,000 participants representing a cross section of the U.S. population were tested for antibodies for HEV. According to the results, HEV exposure was less common in children than in adults and generally increased with age. Males had higher prevalence of HEV antibodies than women. Individuals living in the South were less likely to be seropositive; those in the Midwest had the highest regional seropositive estimates.

“The very high prevalence of antibodies to the HEV among residents of the U.S. was quite surprising; however HEV-associated acute hepatitis has been increasingly reported among residents of western European countries. In addition, HEV infections are an important cause of illness and even death among populations in developing counties, especially among women who are infected during pregnancy,” said Kenrad E. Nelson, senior author of the study and professor in the Bloomberg School’s Department of Epidemiology.

The study was supported by a grant from the National Institute of Allergy and Infectious Diseases, a member of the National Institutes of Health.

In addition to the Johns Hopkins authors, the study was published by Robert H. Purcell and Ronald E. Engle, both of NIAID; and Geraldine M. McQuillian and Annemarie Wasley, both of the Centers for Disease Control and Prevention.