Hepatitis A virus (HAV), a member of the Picornaviridae family.
The virus is acquired directly from infected individuals by the faecal–oral route or by close contact, or by consumption of contaminated food or drinking- water. There is no insect vector or animal reservoir (although some non-human primates are sometimes infected).
Nature of the disease
An acute viral hepatitis with abrupt onset of fever, malaise, nausea and abdominal discomfort, followed by the development of jaundice a few days later. Infection in very young children is usually mild or asymptomatic; older children are at risk of symptomatic disease. In adults, the disease is often more severe and full recovery may take several months. Case-fatality is greater than 2% for those over 40 years of age and 4% for those over 60.
Worldwide, but most common where sanitary conditions are poor and the safety of drinking-water is not well controlled (Map).
Risk for travellers
Non-immune travellers to developing countries are at significant risk of infection. The risk is particularly high for travellers exposed to poor hygiene, sanitation and drinking-water control.
Travellers who are non-immune to hepatitis A (i.e. have never had the disease and have not been vaccinated) should take particular care to avoid potentially contaminated food and water.