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Many clear hepatitis B proteins without treatment

NEW YORK, Nov 05 (Reuters Health) - Seventy percent of people infected with the hepatitis B virus (HBV) will clear proteins linked to acute illness from their bodies after 10 years without drug treatment, according to the results of a study.

The findings suggest that patients who do not clear these proteins--known as e-antigens--from their bodies may be good candidates for antiviral treatment, Dr. Brian J. McMahon of the US Centers for Disease Control and Prevention's Arctic Investigations Program in Anchorage, Alaska, and colleagues write in the November 6th issue of the Annals of Internal Medicine.

While most people recover within a few months of HBV infection, some can develop chronic infection, which can lead to cirrhosis (scarring), liver cancer, liver failure and death. Hepatitis B vaccine is available for all age groups to prevent HBV infection.

Little is known about how frequently people are able to clear infection on their own and how frequently those with chronic HBV infection go on to develop liver cancer or liver failure.

To investigate, McMahon's team followed 1,536 Alaska Natives with chronic HBV for several years. All study participants had blood samples taken every 6 months during the study period. Levels of two virus-related proteins--hepatitis B surface antigens and e-antigens--were also measured to gauge the severity of infection.

Forty percent of the patients had e-antigens in their blood at the time they entered the study. Having e-antigen in the blood generally means a person has "very active liver disease and a lot of virus present," according to a patient summary published with the study.

After 12 years, the researchers found that two thirds of patients who initially tested positive for e-antigen cleared the protein from their bodies and developed antibodies to it. Based on their findings, McMahon and colleagues estimate that more than 70% of e-antigen-positive people with HBV infection will clear the antigen from their bodies within 10 years, without drug treatment.

But about 15% of these patients became e-antigen-positive again during the study period. These patients, as well as older patients, were more likely to develop liver cancer, the report indicates.

The number of new infections of HBV per year has declined in the US from an average of 450,000 in the 1980s to about 80,000 in 1999, with the highest rate of disease occurring in 20- to 49-year-olds, according to the CDC. The greatest decline has been among children and adolescents, due to routine HBV vaccination.

The agency estimates that 1.25 million Americans are chronically infected with HBV, of whom 20% to 30% acquired the infection in childhood.

SOURCE: Annals of Internal Medicine 2001;135:759-768.

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