This article is from the Childhood Vaccinations FAQ, by Lynn Gazis-Sax firstname.lastname@example.org with numerous contributions by others.
There are several forms of hepatitis (infection of the liver) which
cause jaundice, nausea and weakness. Hepatitis A is caused by
infection with hepatitis A virus (HAV) which is acquired primarily
through a fecal-oral route, most often from person to person. It can
also occur via ingestion of contaminated food or water. The illness
consists of mild flu-like symptoms or severe nausea lasting for
weeks. Hepatitis A does not become chronic and is rarely fatal. In
children under 6, most cases (>70%) of hepatitis A are asymptomatic,
and if illness occurs, it is usually not accompanied by
jaundice. Among older children and adults, the illness is usually
symptomatic, and jaundice occurs in >70% of cases. Symptoms usually
last for <2 months, but 10-15% of people infected have illness or
relapses for up to 6 months. 11-22% of people who have hepatitis A are
hospitalized, and hepatitis A is responsible for an estimated 100
deaths a year (these numbers from the ACIP recommendation on hepatitis
A - the AAP recommendation gives similar, but not identical, numbers).
Hepatitis A should not be confused with hepatitis B, which is less
contagious but more serious. Hepatitis B becomes chronic in 5-10% of
those infected. Complications include hepatic necrosis, cirrhosis of
the liver, chronic active hepatitis, and hepatocellular carcinoma.
Some sources of general information on hepatitis can be found in the
hepatitis B section of this FAQ.