Chronic hepatitis B

Background

Chronic hepatitis B virus (HBV) infection remains a major public health risk. The Centers for Disease Control and Prevention has released recommendations to guide management of patients with this common viral illness.

Conclusions

The prevalence of chronic HBV infection in the United States is approximately 1 million patients, and the virus is responsible for up to 4,000 deaths a year. The majority of US residents with chronic Hepatitis B infections were born outside of the country.

HBV replicates in the liver after hematogenous dissemination. Immunosuppressed adults and children younger than 5 years are usually asymptomatic. Symptoms occur in only 30 percent-50 percent of patients over the age of 5 years. Symptoms of acute disease occur 2-3 months after exposure and include fatigue, anorexia, nausea, low-grade fever, abdominal pain, and jaundice. Duration of the illness is typically 2-4 months. The case fatality rate of acute hepatitis B is approximately 1 percent, with higher rates in the elderly.

Acute infected patients who do not develop chronic hepatitis B will become hepatitis B surface antigen (HbsAG)-negative, hepatitis core antibody (HbcAb)-positive, and HbsAb (Anti-HBs) positive.

Acute hepatitis B infection becomes chronic in more than 90 percent of infants, 25 percent-50 percent of children younger than 5 years, and less than 5 percent of the remaining population. Immunosuppressed patients and patients of hemodialysis have higher rates of conversion to chronic infection.

There are three phases of chronic HBV infection: immune tolerance (positive hepatitis Be antigen (HBeAg), high viral levels, inactive liver disease) chronic hepatitis (variable HbeAg status, high viral levels, and active liver disease. And inactive disease (positive hepatitis Be antibody (HbeAb), low viral levels, and normal transaminese levels).

The presence of HbeAg and HBV DNA indicate high levels of viral replication. Anti-HBe usually reflects diminished viral replication.

Death from cirrhosis or liver cancer eventually occurs in 25 percent of chronically infected children younger than 5 years and 15 percent older patients. Those with hepatic inflammation and fibrosis are at higher risk for hepatocellular carcinoma.

Patients with chronic HBV infection have a 0.5 percent rate of spontaneous resolution.

Implementation

The following populations should be tested for chronic HBV infection: those born in regions with prevalence greater than 2 percent intravenous drug users, homosexual men, patients to receive immunosuppressive therapy, hemodialysis patients, all pregnant women, household contracts of patients with chronic infection, HIV-positive patients, and persons whose bodily fluids have been exposed to those of others, such as through needlesticks.

Detection of HbsAg is the primary method of diagnosis. No rapid or oral fluid diagnostic tests are available in the United States. All positive HbsAg laboratory results should be reported to local health departments in accordance with state regulations.

Most transmission of HBV results from close personal contact with patients who harbor chronic HBV infection. Among household contacts of chronic HBV patients, 3 percent-20 percent also harbor chronic HVB. A substantial minority of other contacts show evidence of resolved HBV infection. Chronic HBV infections are present in approximately 1 percent of homosexual men.

More than 90 percent of new infections worldwide have occurred in children younger than age 5 years by perinatal or household transmission. Hepatitis B vaccination has reduced incidence of the disease by 98 percent in children younger than age 15 years over the last two decades.

Sexual, household, and needle-sharing contacts should be identified and tested. Susceptible contacts should receive HBV vaccine. It is estimated that fewer than 20 percent of contacts receive vaccination.

Patients with chronic infection should be counseled about risks of transmission and techniques to reduce risks to contacts. They should cover skin lesions to prevent spread of infectious secretions, clean any blood spills with bleach, refrain from sharing household articles that could become contaminated with blood (such as toothbrushes or razors), employ safe sex techniques, and inform medical and dental personnel of their status prior to treatment. HBV is not spread by breastfeeding, kissing, coughing, or sharing eating utensils of glassware.

HBV remains infectious on environmental surfaces for at least 7 days. Nevertheless, no evidence supports transmission by workplace contact, and transmission rarely occurs in child care settings.

Chronically infected patients should receive hepatitis A vaccine in two doses 6-18-months apart if chronic liver disease is present.

There are seven FDA-approved therapies for chronic hepatitis B infection, and others are undergoing clinical trials. Optimal duration of therapy is not currently known. Combination therapy has not been shown to improve responsive rates, but more studies are needed.

Serologic end points of therapy include elimination of HBeAg, undetectable HBV DNA, and loss of HBeAg. Therapy should continue for at least 6 months after eliminations of HBeAg and emergence of anti-HBe. (Patients should be monitored for relapse after cessation of therapy).