What is the infectious agent that causes hepatitis A?
Hepatitis A infection is caused by the hepatitis A virus. Hepatitis A virus is passed in the stool of infected persons. Unlike many other viruses, it can survive for a long time at room temperature in food and on surfaces and objects. The virus is not affected by cold or by freezing, but it is inactivated by heating foods to >185^o F (85^o C) for one minute. Adequate chlorination of water also kills the hepatitis A virus.

Where is hepatitis A found?
Hepatitis A infection occurs worldwide. The disease is common in Africa, Asia (except Japan), parts of the Caribbean, Central and South America, Eastern Europe, the Mediterranean Basin, and the Middle East. In the United States, hepatitis A occurs in isolated cases, in outbreaks, and in widespread epidemics.

How do people get hepatitis A infection?
Hepatitis A virus is usually spread from person to person. People get hepatitis A infection by putting something in the mouth that has been contaminated with the stool of an infected person. For this reason, the virus is more easily spread in places with poor sanitary conditions or in places where people are not careful about washing their hands.

Persons with hepatitis A can also spread the virus to household members and to sex partners. In rare cases, people have been infected after getting a transfusion of infected blood. Outbreaks of hepatitis A have also occurred among illegal drug users. The virus is not spread by casual contact, as in the usual work or school setting.

Because the virus can live in the environment for a long time, people can also get hepatitis A by:

• Swallowing contaminated water or ice
• Eating raw or undercooked shellfish harvested from sewage-contaminated water
• Eating raw fruits, vegetables, or other foods that were contaminated during growing, harvesting, processing, or handling
• Eating cooked foods that were contaminated after cooking

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What are the signs and symptoms of hepatitis A?
Children infected with hepatitis A virus often have no symptoms. Most adults have symptoms that develop over several days. Symptoms include:

• Fever
• Tiredness
• Loss of appetite
• Nausea, vomiting, or stomach ache
• Dark urine
• Jaundice (yellowing of the skin and whites of the eyes)

If symptoms do occur, they usually last less than 2 months, although 10% to 15% of persons have prolonged or relapsing disease that can last up to 6 months.

How soon after exposure do symptoms appear?
The average time between exposure to the virus and the development of symptoms is about 28 days. Signs of illness usually begin abruptly. Infected persons with no symptoms can still spread the virus. This often happens with young children who unknowingly spread hepatitis A virus to older children and adults.

How is hepatitis A diagnosed?
Hepatitis A can be diagnosed by a blood test called IgM anti-HAV.

Who is at risk for hepatitis A?
Anyone who has not already been infected with hepatitis A virus can become infected, but some people are at increased risk:

• Persons who share a household or have sexual contact with someone who is infected with hepatitis A virus
• Children and staff in child-care centers (especially centers where children are in diapers) where someone has hepatitis A virus infection
• Travelers to countries where hepatitis A is common and where proper sewage disposal and clean water, food, and sanitation are not available
• Residents and staff of institutions for developmentally disabled persons where someone has hepatitis A
• Men who have sex with men
• Persons who use street drugs
• Workers who handle animals infected with hepatitis A virus or who work with hepatitis A virus in a research laboratory
• Persons with clotting factor disorders who receive injections of factor concentrates

What complications can result from hepatitis A?
Unlike other types of hepatitis, such as hepatitis B and hepatitis C, hepatitis A causes no long-lasting liver damage. Deaths from hepatitis A infection are rare.

What is the treatment for hepatitis A?
There is no treatment for hepatitis A infection. People usually recover on their own after 2 or 3 weeks of bed rest. Having had the disease produces lifelong protection against future hepatitis A virus infection.

How common is hepatitis A?
In the United States, about 180,000 persons become infected with hepatitis A virus yearly, most from person-to-person contact. Outbreaks occur periodically in many American Indian, Alaska native, Pacific Islander, and some religious communities. These outbreaks occur mainly among young children.

How can hepatitis A be prevented?
1. Hepatitis A vaccine provides long-term protection. The vaccine is licensed for use in persons 2 years of age and older. It must be given before exposure to the hepatitis A virus. Two shots are needed for long-term protection.

Hepatitis A vaccine is recommended for:

• Persons who travel to or work in areas where hepatitis A is common. The first dose should be given at least 4 weeks before travel.
• Children living in communities with high rates of hepatitis A, such as Alaska native villages, American Indian reservations, and Pacific Islander and some religious communities
• Men who have sex with men
• Persons who use street drugs
• Persons with chronic liver disease
• Persons with clotting factor disorders, such as hemophilia
• Persons who work with animals infected with hepatitis A virus or who work with hepatitis A virus in a research setting

The vaccine is not recommended for children under age 2. Immune globulin is recommended in this age group for short-term protection.

2. To prevent person-to-person spread, good personal hygiene and proper sanitation are important. Always wash hands with soap and warm water after using the toilet and changing a diaper and before eating or preparing food.