Infection is via the faecal-oral route and is commonly contracted by drinking or eating contaminated food or water. It is also common in individuals who travel to parts of the world where public hygiene is poor. HAV can also be transmitted as a result of close contact between individuals. Food which has been prepared by someone with the infection may become contaminated, as will food which has been cleaned with contaminated water. Therefore, care should be taken when eating food such as salads, raw vegetables and fruits to ensure that it has been adequately washed in clean water.
Shellfish are also risky as they filter contaminants out of the water in which they live.
It is common for outbreaks to occur in close communities such as schools and nursing homes. The acute phase is characterised by feelings of malaise, headache, nausea and vomiting, diarrhoea and abdominal pain. Jaundice may occur with symptoms which include yellowing of the whites of the eyes, yellowish skin, dark urine and light-coloured stools. Some individuals will be asymptomatic. The incubation period is two to six weeks.