Feb. 14, 2011 -- The incidence of new hepatitis C virus (HCV) infections in the U.S. declined by more than 90% between 1990 and 1992 and has remained relatively stable ever since, new figures from the CDC confirm.
Although the reasons for the dramatic drop are not fully understood, researchers attribute much of it to a shift away from needles to other delivery systems by users of illicit drugs and the fact that most IV drug users had become infected by the early 1990s.
Illicit IV drug use is the most common source of new hepatitis C virus infection today, and this has been the case since the CDC first started collecting surveillance data in the early 1980s.
“New IV drug users are still being infected in high numbers, but they represent a very small percentage of the pool of people who are infected,” researcher Miriam J. Alter, PhD, of the University of Texas Medical Branch in Galveston, tells WebMD.
Transfusions and Tattoos
Alter and colleagues tracked the national incidence and transmission of new HCV infections between 1982 and 2006 by analyzing data provided by six county health departments.
Among other major findings:
- There was little evidence that cosmetic practices such as tattooing and body piercing have contributed substantially to HCV infections in the U.S.
- Approximately 14% of new HCV infections identified during the surveillance period occurred among people who said their only risk factor was having sex with an infected partner or having multiple sex partners.
- The HCV infection risk from blood transfusions fell to near negligible levels -- about one infection for every 2 million units of transfused blood -- following the introduction of tighter donor screening practices and better tests to detect HCV in donated blood in the early 1990s.
HCV and Baby Boomers
About 3.2 million people in the U.S. are chronically infected with hepatitis C, and about 17,000 new infections occur each year, according to the CDC.
“It is important to remember that most people walking around with HCV today are not current IV drug users or longtime street users,” Alter says. “The chronically infected population is made up largely of people who gave up their risky behaviors a long time in the past.”
CDC Division of Viral Hepatitis Director John Ward, MD, tells WebMD that at the height of hepatitis C infections, more than 300,000 infections occurred each year.
About one in 30 baby boomers are infected with hepatitis C, but most do not know it, Ward says.
Available treatments cure a significant percentage of people with persistent HCV infection, and new drugs are on the horizon that will cure more people with the virus, he says.
“There is no guarantee that the decline in HCV transmission observed in this report will be seen in the future,” Ward says. “We can’t become complacent. We have to keep our prevention and surveillance programs in place to avoid losing ground.”