CDC Researchers Release Latest Hepatitis A, B, and C Statistics

By Liz Highleyman

The Centers for Disease Control and Prevention (CDC) Division of Viral Hepatitis recently updated its web site with new estimates of the disease burden for viral hepatitis in the U.S. in 2007, including estimates of chronic hepatitis B and chronic hepatitis C prevalence and hepatitis-related deaths.

The latest statistics are available online.

In related news, CDC researchers published updated epidemiological data on acute viral hepatitis in the May 22, 2009 Morbidity and Mortality Weekly Report Surveillance Summaries.

FIGURE 1. Incidence* of acute hepatitis A, by year --- United States, 1982--2007

Incidence* of acute hepatitis B, by year --- United States, 1982--2007

FIGURE 17. Incidence* of acute hepatitis C, by year --- United States, 1992--2007

In the U.S., acute viral hepatitis is most frequently caused by hepatitis A virus (HAV), hepatitis B virus (HBV), or hepatitis C virus (HCV) infection, the report authors noted as background. Safe and effective vaccines are available for hepatitis A and B, but there is currently no vaccine for against hepatitis C.

While acute hepatitis A resolves spontaneously, a proportion of people with acute hepatitis B or C will go on to develop chronic infection (lasting longer than 6 months), which over years or decades can progress to advanced liver disease including cirrhosis and hepatocellular carcinoma.

Cases of acute viral hepatitis are reported voluntarily to the CDC by state and territorial health departments via the agency's National Notifiable Disease Surveillance System (NNDSS). Reports are received electronically via the CDC's National Electronic Telecommunications System for Surveillance (NETSS).

The MMWR report covers information collected during 2007, the most recent year for which data are available; these data were compared with those from previous years.

Findings:

Acute hepatitis A incidence (new cases) has declined by 92% over the past decade, from 12.0 cases per 100,000 persons in 1995 to 1.0 per 100,000 persons in 2007 -- the lowest rate ever recorded.

Declines in hepatitis A were greatest among children and in states where routine HAV vaccination of children has been recommended since 1999.

Acute hepatitis B incidence has declined by 82%, from 8.5 cases per 100,000 persons in 1990 to 1.5 per 100,000 persons in 2007, also the lowest rate ever recorded.

Declines occurred in all age groups, but were greatest among children younger than 15 years of age.

Acute hepatitis C incidence declined steadily after a peak in 1992, but incidence rates have plateaued since 2003.

In 2007 -- as in previous years -- the majority of acute hepatitis C cases occurred among adults, with injection drug use being the most common risk factor.

"The results documented in this report suggest that implementation of the 1999 recommendations for routine childhood hepatitis A vaccination in areas of the United States with consistently elevated hepatitis A rates has reduced rates of infection," the authors wrote. "In addition, universal vaccination of children against hepatitis B beginning in 1991 has reduced disease incidence substantially among younger age groups."

However, they continued, "Higher rates of hepatitis B continue among adults, particularly among males aged 30-44 years, reflecting the need to vaccinate adults at risk for HBV infection."

The decline in hepatitis C incidence after 1992, the authors noted, was primarily attributable to a decrease in incidence among injection drug users. "The reasons for this decrease were unknown," they wrote, "but probably reflected changes in behavior and practices among injection drug users" -- and may also reflect public interventions such as education and needle exchange programs.

Translating these findings into public health guidelines, the authors stated that the 2006 expansion of routine hepatitis A vaccination recommendations to include all children aged 12-23 months is expected to reduce hepatitis A rates even further.

Ongoing hepatitis B vaccination programs, they wrote, "ultimately will eliminate domestic HBV transmission, and increased vaccination of adults with risk factors will accelerate progress toward elimination."

Prevention of hepatitis C, they said, "relies on identifying and counseling uninfected persons at risk for hepatitis C (e.g., injection drug users) regarding ways they can protect themselves from infection."

"Further prevention of hepatitis B and hepatitis C," they added, "relies on identifying and preventing transmission of HBV or HCV in hospital and non-hospital health-care associated settings." In recent years there have been several reported outbreaks of viral hepatitis due to improper cleaning or reuse of medical equipment.

Division of Viral Hepatitis, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC, Atlanta, GA.

6/19/09

Reference
D Daniels, S Grytdal, and A Wasley. Surveillance for acute viral hepatitis -- United States, 2007. Morbidity and Mortality Weekly Report Surveillance Summary 58(SS03): 1-27. May 22, 2009.

Other Source
Centers for Disease Control and Prevention. Division of Viral Hepatitis. Statistics and Surveillance. Revised June 2, 2009.