There has been a four-fold increase in the incidence of hepatitis A in the past year, according to the latest bulletin of the Virus Reference Laboratory in UCD, writes Carol Coulter.The number of samples which tested positive for the hepatitis A virus from May 1996 to May 1997 rose from 10 per 1,000 to 40 per 1,000. There was no increase in the number of samples sent in for testing. Hepatitis A is a viral infection of the liver. Less severe than hepatitis B or C, it ranges from being asymptomatic (usually in infants) to producing quite severe symptoms of fever, vomiting and weight loss. People can die from it, but this is rare.