Hepatitis B

Alternative names:

acute hepatitis B

Definition:

An inflammation of the liver caused by the hepatitis B virus.

Causes, incidence, and risk factors:

In the general population, hepatitis B is considered primarily a sexually-transmitted disease. It is also transmitted in blood (hence the name serum hepatitis) and, prior to the availability of hepatitis B vaccine, health care professionals such as doctors, nurses, and emergency personnel were at risk for contracting hepatitis B. Because it is very easily transmitted by blood (one virus particle can cause disease), intravenous drug users who share needles and syringes are at extremely high risk. The other common mode of transmission is from hepatitis B infected mothers to the fetus prior to birth.

There are many different viruses that cause hepatitis including hepatitis A, hepatitis C, Delta factor hepatitis, and hepatitis E. The initial course for hepatitis A and B may be similar but it is hepatitis B that can have long term consequences. Once infected with the hepatitis B virus, approximately 10% of the people develop a chronic permanent infection (chronic carrier state). In this group, a small proportion of people will develop slow but progressive liver damage leading to cirrhosis or hepatocellular cancer. Hepatitis B is thought to be the leading cause of liver cancer in the United States.

Hepatitis B has a long incubation period, occasionally taking up to 6 months to manifest itself. Early symptoms may be a variety of skin rashes and achy joints (arthralgia). Systemic symptoms include fever, malaise, and abdominal pain or discomfort. Ultimately the yellow color of jaundice appears, first in the whites of the eyes and then the skin. Jaundice is usually associated with dark urine and light or clay colored stools. Hepatitis B is a serious disease and mortality (death rate) during the acute stage is approximately 1%.

The overall incidence of reported hepatitis B is 2 per 10,000 individuals, but the true incidence may be higher, because many cases do not cause symptoms and go undiagnosed and unreported. Pregnant women are now routinely screened for hepatitis B and, as it is a reportable disease, more accurate figures are available. One in 1,000 pregnant women are chronic carriers of hepatitis B. (Note: the incidence is higher in people of Southeast Asian heritage.)

People at highest risk for acquiring hepatitis B infection continue to be those who are homosexual or bisexual, IV drug users, and female partners of these individuals. Because hepatitis B immunization (vaccine) is available, the risk to health-care workers, hemodialysis patients, individuals requiring multiple blood transfusions, and newborn infants has been reduced.