Viral Hepatitis Strategic Plan

Overview of Viral Hepatitis

Hepatitis B

Overview

Hepatitis B infection is caused by the hepatitis B virus (HBV). More than 250,000 persons die worldwide each year of hepatitis B associated acute and chronic liver disease. An estimated 1.25 million persons in the United States have chronic HBV infection. Chronic infection occurs in 90% of infants infected at birth, 30% of children infected at age 1-5 years, and decreases to 6% of persons infected after age of 5 years. In 2001, the number of reported acute cases of hepatitis B in the U.S. was 7,844. From 1982 to 1998, the reported incidence of acute HBV infection declined by 76.1%, from 13.8 cases/100,000 in 1987 to 3.3 cases/100,000 in 1998.8

Clinical Features

The incubation period for hepatitis B ranges from 45 to 160 days with an average of 120 days. Approximately 30% of individuals infected will not have symptoms. Children are less likely to have symptoms than adults. Individuals who do have symptoms experience jaundice, fatigue, abdominal pain, loss of appetite, nausea, vomiting and joint pain.

While most acute HBV infections in adults result in complete recovery, about 1-2% will develop fulminant hepatitis, with a 63-93% mortality rate. Chronic HBV infection is responsible for most of the morbidity and mortality due to hepatitis B including chronic hepatitis, cirrhosis, hepatocellular carcinoma, and death. Chronic active hepatitis B develops in over 25% of HBV carriers and often results in cirrhosis. Persons with chronic HBV infection are at 12 to 300 times higher risk for hepatacelluar carcinoma than non-carriers.9 An estimated 1,000-5,000 persons die each year in the U.S. from HBV related liver cancer.

Diagnosis

Serologic testing is required to make the diagnosis of HBV. Hepatitis B surface antigen (HBsAg) is present in either acute or chronic infection.

The presence of IgM antibody to hepatitis B core antigen (IgM anti-HBc) is diagnostic of acute HBV infection. Antibody to HBsAg (anti-HBs) is produced following a resolved infection and is the only HBV marker found following vaccination. The presence of HBsAg with a negative test for IgM anti-HBc is indicative of chronic HBV infec-tion. The presence of hepatitis B core antibody (anti-HBc) may indicate either acute, resolved, chronic infection, or a false positive result.9 Individuals with hepatitis B may also have elevated liver function tests, especially during the acute phase of illness.

Transmission

HBV is found in blood and certain body fluids such as serum, semen, vaginal secretions, and saliva, of persons infected with HBV. HBV is not found in sweat, tears, urine, or respiratory secretions. Person-to-person spread of HBV can occur among those living with someone chronically infected with hepatitis B. Contact with even small amounts of infected blood can cause infection. HBV is spread by sexual contact with an infected person; sharing needles during injection drug use; occupational needle sticks or sharps exposures; or from an infected mother to her baby during birth. Transmission through receipt of blood or blood products has virtually been eliminated in the U.S. through donor screening. Over 30% of those infected with HBV do not know how they contracted the virus.

At-Risk Groups

At-Risk Groups At risks groups for hepatitis B include:

  • Persons with multiple sex par tners or diagnosis of a sexually transmitted disease,
  • Men who have sex with men,
  • Sexual contacts of infected persons, v Injection dr ug users,
  • Household contacts of chronically infected persons,
  • Infants born to infected mothers,
  • Infants/children of immigrants from areas with high rates of hepatitis B infection, Hepatitis B
  • Health care and public safety workers, and
  • Hemodialysis patients.

According to the CDC, in 2001 the most commonly reported risk factor for HBV infection was high-risk heterosexual activity (24%), followed by injection drug users (21%) and men having sex with men (17%) . Over half of all patients (55.5 ) repo ted treatment for a sexually transmitted disease (STD) or incarceration in a prison or jail prior to their illness.10

Treatment

The primary goal of treatment is to eliminate the virus or decrease its replication and decrease inflammation of the liver. Currently there are three FDA-approved drugs for the treatment of chronic hepatitis B. They include lamivudine, adefovir dipovoxil and interferon alfa-2b. These drugs are effective in up to 40% of patients. Not everyone infected with hepatitis B will need treatment. A thorough medical evaluation by a physician or liver specialist should be performed prior to treatment.

Prevention

Immunization with the hepatitis B vaccine is the most effective means of preventing HBV infection. In 1982, the first hepatitis B vaccine was developed and approved for use. Since the introduction of the hepatitis B vaccine in the U.S., the rates of infection have dropped from 200,000-300,000 prior to 1982, to an estimated 79,000 in 2001.11 Currently in the U.S., there are two single-antigen hepatitis B vaccines available (Recombivax and Engerix B), in addition to the three combination vaccines containing HBV antigen (COMVAX, Twinrix, Pediarix). COMVAX is a combination HBV and Haemophilus influenzae type B (Hib) vaccine. In 2001, the FDA approved a combination hepatitis A and B vaccine (Twinrix) . This vaccine is licensed for use in those 18 years and older. Each vaccine is a three dose series. In December 2002, the FDA licensed Pediarix, a combined diphtheria and tetanus toxoids and acellular per tussis (DTaP) , hepatitis B (HepB) and poliovirus (IPV) vaccine (DTaP-HepB-IPV) for use in infants.

The hepatitis B vaccine is recommended for the following groups:

  • All children aged 0-18 years old who have not been vaccinated,
  • Injection dr ug users,
  • Sexually active heterosexuals with multiple sexual par tners,
  • Persons diagnosed with an STD,
  • Men who have sex with men,
  • Sexual contacts of people with chronic hepatitis B,
  • Household contacts of people with chronic hepatitis B,
  • Health care workers or others with potential occupational exposure to hepatitis B,
  • Hemodialysis patients, and
  • Inmates.

Until universal access to hepatitis B vaccination is achieved, measures such as substance abuse treatment and harm reduction, including syringe access, remain important to prevent hepatitis B infection.

Although high immunization coverage rates have been achieved in infants and younger adolescents, hepatitis B incidence remains high because most new infections occur in adults. Up to 70% of newly infected persons previously received care in settings where they could have been vaccinated, such as in STD clinics, drug treatment programs, and correctional facilities.10 Since high rates of protection are achieved following each dose of vaccine, hepatitis B vaccination should be initiated even if completion of the series cannot be assured.

Hepatitis B immune globulin (HBIG) is available for postexposure prophylaxis. It is recommended for accidental occupational exposures (percutaneous or mucous membrane) , sexual exposure to an HBsAg-postive person, perinatal exposure of infants, or household exposure of an unvaccinated infant less than 12 months old to a primary care-giver with acute hepatitis B. Unvaccinated persons should also initiate the hepatitis B vaccine series. HBIG is most effective when administered within 7 days of exposure.