This article is more than 5 years old. Information may no longer be current.
Acute hepatitis disease rates reach lowest point in U.S.
Children are experiencing a great reduction in the rate of acute hepatitis A and B.
Click Here to Manage Email Alerts
Hepatitis A incidence has declined 88% since 1995, and hepatitis B incidence has declined 79% since 1990, according to a report from the CDC. These incidence rates are the lowest ever reported.
Hepatitis C incidence dropped as well, but adults were most commonly affected, and IV drug use was the most common route to infection.
Annemarie Wasley, ScD, and colleagues from the division of viral hepatitis, National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, CDC, published their findings on hepatitis incidence in the Morbidity and Mortality Weekly Report. They compared 2005 rates of hepatitis with previous years using the National Notifiable Diseases Surveillance System.
Reducing hepatitis
The researchers identified an average of 28,000 cases of acute hepatitis A each year from 1987 to 1997; vaccine became available in 1995. In 1996, vaccination guidelines recommended hepatitis A vaccination for people facing an increased risk, which included men who have sex with men, international travelers, IV and non-IV drug users and children in communities with high hepatitis A rates.
In 1999, the Advisory Committee on Immunization Practices recommended that children in 10 western states and one southern state that had a hepatitis A rate of at least 20 per population of 100,000 receive routine immunization. The ACIP also recommended that six states that had a rate of at least 10 but less than 20 per population of 100,000 consider immunization of children, according to the researchers.
The United States began a four-part strategy against HBV in 1991: universal vaccination of infants at birth, routine screening of pregnant women and immunoprophylaxis for the infants with mothers who were infected or of unknown infection status to prevent perinatal infection, routine vaccination of children and adolescents who were not vaccinated at birth and vaccination of high-risk adults. High-risk adults include dialysis patients, health care workers, IV drug users, MSM, household or sex contacts of people who have chronic HBV infection, people who report a recent history of multiple sex partners or an STD and recipients of certain blood products.
Approximately 3.2 million people in the United States are infected with hepatitis C virus, according to the researchers. Because no vaccine is available, recommendations against hepatitis C focus on prevention efforts to decrease risk for transmission.
Reductions in children
All states report basic information on hepatitis including the event date, source of report and demographic data, according to the researchers. A variable proportion of infections with hepatitis viruses occur without symptoms. More than 70% of hepatitis A infections among children are asymptomatic, although most infections in adolescents and adults are symptomatic.
Similarly, most infants and children with HBV infection are asymptomatic, whereas 30% to 50% of older children and adults present with clinical signs and symptoms. About 60% to 70% of people newly infected with hepatitis C virus are asymptomatic. Investigators suggest that two to three cases of clinical hepatitis are not reported for every reported case.
Because surveillance does not include people with asymptomatic infections, the researchers adjusted the observed rates to account for underreporting and asymptomatic infections.
Overall, hepatitis A rates steadily declined since 1995, when the last peak occurred, according to Wasley and colleagues. In 2005, they found the lowest rate of acute hepatitis A cases ever reported (n=4,488) and an incidence rate of 1.5 per population of 100,000. After accounting for asymptomatic cases and underreporting, the researchers estimated that 42,000 new infections occurred in 2005.
The highest rates of hepatitis A were historically in children and young adults, but since 1997 rates among children declined more rapidly than among other age groups. In 2005, rates by age group were similar. The researchers found 1 per 100,000 cases among children aged younger than 5 years and 1.8 per 100,000 cases among children and young adults aged 5 to 24 years.
The researches noted 5,494 cases of acute hepatitis B and an overall incidence of 1.8 per 100,000 cases, which was also the lowest rate ever reported in the United States. After accounting for asymptomatic cases and underreporting, the researchers estimated 51,000 new infections occurred in 2005.
The highest rates of hepatitis B were notes among people aged 25 to 44 years (3.6 per 100,000), whereas the rate was 0.03 per 100,000 among children aged younger than 15 years, according to the researchers. All age groups experienced declines, however. Children aged younger than 15 experienced a 98% decline, and people aged 15 to 24 years experienced a 90% decline. In addition, adults aged 25 to 44 years experienced a 74% decline, and adults aged older than 45 years experienced a 58% decline, according to the researchers.
The overall national rate of acute hepatitis C was 0.2 per 100,000 in 2005, according to Wasley and colleagues. They noted 671 cases that year and estimated about 20,000 new infections after taking asymptomatic infection and underreporting into account.
People aged 25 to 39 years have the highest rates of disease and experienced the greatest decline. They experienced a decline of 58% since 2000 and 92% since 1992. The researchers found few reports of hepatitis C among adolescents and children aged younger than 15 years.
Continued hepatitis surveillance is key, according to the researchers, as surveillance is able to detect outbreaks, identify people who might require post-exposure prophylaxis and follow trends regarding hepatitis infection.
For more information:
- Wasley A, Miller JT, Finelli L. Surveillance for acute viral hepatitis – United States, 2005. MMWR. 2007;56:1-24.