Hepatitis A is caused by the hepatitis A virus. Up to 90% of hepatitis A infection in children goes with no symptoms or without jaundice. Cases with jaundice, more common in adults, present with this symptom and also general symptoms (fever, loss of appetite, nausea, vomiting, etc.) which may last for several weeks. About 15% of patients have prolonged or relapsing symptoms over a 6–9-month period. No specific treatment is available, and patients recover spontaneously.

Humans are the only reservoir of hepatitis A virus, which is transmitted from faeces of infected patients, either by person-to-person contact or by consumption of contaminated food or water. Sexual transmission among men who have sex with men has also been described. The incubation period of symptomatic cases ranges between two and seven weeks. Patients are infectious from two weeks before the onset of symptoms and may continue to be infectious for one week or more after.

Hepatitis A occurs worldwide. Transmission can be reduced especially by improving hygiene in food production handling. An effective vaccine is available.