The virus

Hepatitis A virus is a single-stranded RNA virus, which belongs to the genus Hepatovirus in the family Picornaviridae.

Epidemiology

Route of spread

Hepatitis A is spread by the faecal–oral route, through eating and drinking contaminated food and water, and person-to-person spread. Waterborne outbreaks have been described in countries where infection is endemic. Outbreaks have also occurred in intravenous drug users (IVDU) as a result of injecting substances reconstituted in contaminated water, and through oro–anal sex. Rarely it may be transmitted through blood transfusion through a viraemic donor.

Prevalence

In developed countries, because of good hygiene, the majority of adults have not acquired the infection, as compared to the developing countries where >90% of infection occurs in childhood. People travelling to countries with a high prevalence are therefore at risk of acquiring infection during their travel and this is the major risk factor for acquisition of infection in developed countries, most commonly by eating uncooked food e.g. salad washed in contaminated water. Shellfish grown in contaminated water are another source of hepatitis A infection, as they concentrate the virus. In Europe the prevalence of antibody in adults varies from 10–50%. People from lower socio-economic groups are more likely to have had infection.