Transmission

Symptoms and Prognosis

Prevention

Hepatitis A is spread primarily from the stool of one person to the mouth of another, usually because of poor hygiene—for example, when an infected person prepares food with unwashed hands. Hepatitis A is sometimes spread in day care centers, where caregivers and children can come in contact with infected stool in diapers. Shellfish taken from waters where raw sewage drains are sometimes contaminated and can cause infection when they are eaten raw.

Epidemics, usually linked to contamination of water supplies by stool, are common, especially in developing countries.

Most hepatitis A infections cause no symptoms and are unrecognized. However, typical symptoms of acute hepatitis can occur.

Recovery from the acute infection is usually complete except when the infection is very severe (fulminant). Such cases are rare (rarer than with hepatitis B). Also, people with hepatitis A do not become carriers, and the virus does not cause chronic hepatitis.

Using good hygiene in food handling and avoiding contamination of water supplies are important.

Vaccination against hepatitis A is recommended for all children. It is also recommended for adults at high risk of exposure to the infection:

• Travelers to parts of the world where hepatitis A is widespread
• Military personnel
• Day care center employees
• Sanitation workers
• People who work in diagnostic or research laboratories that handle hepatitis A virus
• People with chronic liver disorders or bleeding disorders
• Men who have sex with men
• People who use illicit drugs (who are often infected for reasons other than drug use)

Standard immune globulin* is given to people exposed to hepatitis A. This treatment prevents or decreases the severity of infection and can be given in addition to the vaccine.

Hepatitis B is less easily transmitted than hepatitis A. Transmission commonly occurs when needles are reused without being first sterilized—as when people share needles to inject drugs or when needles are reused to apply tattoos or to inject a vaccine.

Transmission through blood transfusions is possible but is now rare in the United States because blood is screened.

Hepatitis B is also spread through contact with saliva, tears, breast milk, urine, vaginal fluid, and semen.

Transmission commonly occurs between sex partners, both heterosexual and homosexual. Also at increased risk are people in closed environments (such as prisons and institutions for the mentally retarded) because contact with another person's body fluid is more likely. A pregnant woman infected with hepatitis B can transmit the virus to her baby during birth.

Hepatitis B can be transmitted by healthy people who have the virus (carriers). Whether insect bites can transmit this virus is not clear.

Many cases of hepatitis B have no known source.

In general, hepatitis B is more serious than hepatitis A and is occasionally fatal, especially in older people. The infection can be mild or very severe. When people with hepatitis B also have hepatitis D, symptoms are more severe. Joint pains and itchy red hives on the skin (wheals) are more likely in people with hepatitis B than with other hepatitis viruses.

About 5 to 7% of infected adults develop chronic hepatitis B. The rate is higher among children, and the younger the child, the greater the chance of developing chronic hepatitis B.

In the Far East and parts of Africa, hepatitis B virus accounts for many cases of chronic hepatitis, cirrhosis, and liver cancer.

High-risk behavior, such as sharing needles to inject drugs and having several sex partners, should be avoided, as should unnecessary blood transfusions.

Vaccination against hepatitis B protects most people but may provide less protection for people undergoing dialysis, people with cirrhosis, and people with a weakened immune system. These people may need booster doses.

In the United States, vaccination is recommended for all people younger than 18 (starting at birth), but it is especially important for people at risk of exposure to hepatitis B. Worldwide vaccination of all people against hepatitis B is desirable but expensive.

People who have been exposed to hepatitis B, including infants born to mothers with hepatitis B, are given hepatitis B immune globulin and the vaccine. This combination prevents chronic hepatitis B in more than 80%.

Hepatitis C is most commonly transmitted among people who share needles to inject drugs. The infection can also be transmitted through needles used for tattoos and body piercings.

Transmission through blood transfusions is possible but is now rare. Transmission through sexual contact is uncommon, as is transmission from an infected pregnant woman to her baby.

For unknown reasons, about one of five people with alcoholic liver disease has hepatitis C. A small proportion of healthy people appear to be carriers.

Hepatitis C is somewhat unpredictable. At first, the infection is usually mild and often without symptoms. However, liver function may fluctuate repeatedly for several months or years.

Hepatitis C becomes chronic in about 75% of people. Chronic infection is usually mild. However, about 20 to 30% of affected people develop cirrhosis, and liver cancer may occur once cirrhosis has developed.

High-risk behavior, such as sharing needles to inject drugs and getting tattoos and body piercings, should be avoided, as should unnecessary blood transfusions.

No vaccine is currently available. Standard immune globulin* is not useful.

Hepatitis D occurs most often among people who share needles to inject illicit drugs.

Hepatitis D occurs only as a co-infection with hepatitis B and usually makes the hepatitis B infection more severe.

Measures that protect against hepatitis B (such as avoiding high-risk behavior and receiving hepatitis B vaccine and hepatitis B immune globulin) also protect against hepatitis D.

Hepatitis E is spread primarily from the stool of one person to the mouth of another. It occasionally causes epidemics, which are often linked to water contaminated by stool. Epidemics have occurred only in Mexico, Peru, and parts of Asia and Africa, not in the United States or western Europe.

Hepatitis E may cause severe symptoms, especially in pregnant women.

Hepatitis E does not become chronic, and people do not become carriers.

A new vaccine is available.

Standard immune globulin* is ineffective.