Following a prodrome that may include fever, malaise, anorexia, nausea or abdominal discomfort, there is jaundice, and sometimes an enlarged tender liver. Infection may be indicated by the presence of elevated serum aminotransferase levels. Children are often asymptomatic and occasionally present with atypical symptoms, including diarrhoea, cough, coryza or arthralgia. Jaundice is very unusual in children younger than 4 years, and 90 percent of cases in the 4–6 years age group are anicteric.