Food that is handled by infected natives can transmit the disease to unwary tourists, as can vegetables or fruit grown in human night soil and eaten raw. Raw or partially cooked shellfish that come from polluted waters are another source of disease. Transmission by contaminated needles and blood products has been reported. More than 28,000 cases occur each year in the United States, but disease is more common in countries with poor sanitation. Etiology Hepatitis A is caused by an RNA-containing picornavirus.
Symptomatic individuals spend usually at least one month off work.
Some adults and most children are asymptomatic. Preparing the international traveler Protection against hepatitis A is recommended for all travelers to developing countries, and is especially important for those who will visit rural areas or eat in local restaurants. Frequent travelers or those with prolonged stays should get a booster dose at least 6 months after the first. Estimates based on antibody titers suggest immunity after the booster shot may last for more than a decade. Recovery from hepatitis A confers lifelong immunity.