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Epidemiology of hepatitis B
1Hepatitis Branch, Centers for Disease Control and Prevention, Atlanta, GA 30333.
Insights
Hepatitis B virus (HBV) infections are common in the US. Routine infant immunization is the most effective strategy to prevent chronic HBV infections, which can lead to serious liver diseases.
Area of Science:
- Hepatology
- Infectious Diseases
- Public Health
Background:
- An estimated 200,000 to 300,000 hepatitis B virus (HBV) infections occur annually in the United States.
- The risk of chronic HBV infection is inversely proportional to age at the time of acute infection.
- Infants acquiring HBV have the highest risk (70-90%) of chronic infection, while older children and adults have the lowest risk (5-10%).
Purpose of the Study:
- To highlight the significance of HBV infection in the US.
- To emphasize the importance of preventing chronic HBV infection due to its long-term consequences.
- To advocate for routine infant immunization as the most effective control measure.
Main Methods:
- The abstract summarizes existing epidemiological data on HBV infection in the US.
- It analyzes the age-specific risks of acute and chronic HBV infection.
- It reviews common transmission routes and risk factors in different age groups.
Main Results:
- Although children younger than 10 years account for only 8% of acute HBV infections, they contribute 20-30% of all chronic infections.
- Children typically acquire HBV from infected mothers or household contacts.
- In adults and adolescents, sexual activity and injecting drug use are common transmission routes, but a significant percentage have no identifiable risk factor.
Conclusions:
- Prevention of chronic hepatitis B virus infection is crucial due to its association with cirrhosis and liver cancer.
- Routine infant immunization is the most feasible and cost-effective method to control HBV transmission.
- Early vaccination strategies are essential to reduce the burden of chronic HBV infection and its severe health consequences.
Abstract:
An estimated 200,000 to 300,000 hepatitis B virus infections occur annually in the United States. With acute infection, symptoms develop in fewer than 5% of infants, 5 to 15% of children between the ages of 1 and 5 years and 33 to 50% of older children and adults. However, the risk of chronic infection after acute infection is inversely proportional to age. The risk of chronic infection is highest for infants who acquire infection during the perinatal period (70 to 90%), lower for children younger than 5 years (20 to 50%) and lowest for older children and adults (5 to 10%). Therefore although only approximately 8% of acute infections in the United States occur in children younger than 10 years, these infections account for 20 to 30% of all chronic infections. Children usually acquire infection from infected mothers at the time of birth or from infected household contacts. The risk of hepatitis B virus transmission between children in day-care centers and schools is very low. Among adults and adolescents sexual activity and injecting drug use are the most common risks for acquisition of infection, yet at least 30% of reported hepatitis B among adults cannot be associated with an identifiable risk factor. Because chronic hepatitis B virus infection is associated with long term consequences of cirrhosis and primary hepatocellular carcinoma, prevention of chronic infection is the most important reason for vaccination against hepatitis B. Routine infant immunization is the most feasible, cost-effective means to control hepatitis B virus transmission.