Food that is handled by infected natives can transmit the disease to unwary tourists, as can vegetables or fruit grown in human night soil. Raw or partially cooked shellfish that comes from polluted waters are another source of disease. Transmission by contaminated needles and blood products has also been reported. More than 20,000 cases are reported 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. This full level of immunity takes up to 4 weeks to develop, although significant antibody response occurs in the first 2 weeks. 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 two decades.