Key facts

• Hepatitis A is a viral liver disease that can cause mild to severe illness.
• The hepatitis A virus (HAV) is transmitted through ingestion of contaminated food and water or through direct contact with an infectious person.
• Almost everyone recovers fully from hepatitis A with a lifelong immunity. However, a very small proportion of people infected with hepatitis A could die from fulminant hepatitis.
• The risk of hepatitis A infection is associated with a lack of safe water, and poor sanitation and hygiene (such as dirty hands).
• Epidemics can be explosive and cause substantial economic loss.
• A safe and effective vaccine is available to prevent hepatitis A.
• Safe water supply, food safety, improved sanitation, hand washing and the hepatitis A vaccine are the most effective ways to combat the disease.

Hepatitis A is a liver disease caused by the hepatitis A virus. The virus is primarily spread when an uninfected (and unvaccinated) person ingests food or water that is contaminated with the faeces of an infected person. The disease is closely associated with unsafe water or food, inadequate sanitation and poor personal hygiene.

Unlike hepatitis B and C, hepatitis A infection does not cause chronic liver disease and is rarely fatal, but it can cause debilitating symptoms and fulminant hepatitis (acute liver failure), which is often fatal.

Hepatitis A occurs sporadically and in epidemics worldwide, with a tendency for cyclic recurrences. The hepatitis A virus is one of the most frequent causes of foodborne infection. Epidemics related to contaminated food or water can erupt explosively, such as the epidemic in Shanghai in 1988 that affected about 300 000 people1. Hepatitis A viruses persist in the environment and can withstand food-production processes routinely used to inactivate and/or control bacterial pathogens.

The disease can lead to significant economic and social consequences in communities. It can take weeks or months for people recovering from the illness to return to work, school, or daily life. The impact on food establishments identified with the virus, and local productivity in general, can be substantial.

Geographical distribution
Geographical distribution areas can be characterized as having high, intermediate or low levels of hepatitis A virus infection.

Areas with high levels of infection
In developing countries with poor sanitary conditions and hygienic practices, most children (90%) have been infected with the hepatitis A virus before the age of 10 years 2. Those infected in childhood do not experience any noticeable symptoms. Epidemics are uncommon because older children and adults are generally immune. Symptomatic disease rates in these areas are low and outbreaks are rare.

Areas with intermediate levels of infection
In developing countries, countries with transitional economies, and regions where sanitary conditions are variable, children often escape infection in early childhood and reach adulthood without immunity. Ironically, these improved economic and sanitary conditions may lead to accumulation of adults who have never been infected and who have no immunity. This higher susceptibility in older age groups may lead to higher disease rates and large outbreaks can occur in these communities.

Areas with low levels of infection
In developed countries with good sanitary and hygienic conditions, infection rates are low. Disease may occur among adolescents and adults in high-risk groups, such as injecting-drug users, men who have sex with men, people travelling to areas of high endemicity, and in isolated populations, such as closed religious communities. However, when the virus gets introduced in such communities, high levels of hygiene stops person-to-person transmission and outbreaks die out rapidly.

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