That Last Boom of Hep C?

A new study of U.S. blood donors shows a "strikingly lower prevalence" of hepatitis C virus compared with 1992-1993, according to lead researcher Edward Murphy of the University of California, San Francisco.

HCV is a blood-borne infection that is primarily contracted from dirty syringes, but a small number of cases are sexually transmitted or passed from mother to infant during childbirth. The body can clear hepatitis C, though infections become chronic 75% to 85% of the time. The U.S. Centers for Disease Control and Prevention estimates that 1% to 5% of people with chronic HCV eventually die of cirrhosis or liver cancer.

In the early 1990s about 0.5% of blood donors were positive for HCV antibodies, indicating either a chronic infection or past infection that cleared. From 2006 to 2007 the study analyzed samples from nearly 960,000 blood donors at six U.S. blood banks, finding less than 0.1% were positive for HCV antibodies.

Murphy says the decrease probably reflects an overall decline of hepatitis C, especially among younger Americans. The baby boom generation, which had higher rates of injection-drug use than subsequent generations, has more carriers of the infection and is at higher risk for HCV-related liver disease.

Two other factors for higher risk of hepatitis C among blood donors were found. Among women, the odds of having HCV antibodies increased with the number of children they had given birth to - from one infection in 3,300 among women who had never given birth to one in 1,000 among women with five or more children.

Obese adults were less likely than their normal-weight peers to have HCV antibodies. And among those with antibodies, obese persons were less likely to have the genetic material that signals the ongoing presence of HCV.

The study, "Hepatitis C Virus Prevalence and Clearance Among U.S. Blood Donors, 2006-2007: Associations With Birth Cohort, Multiple Pregnancies, and Body Mass Index," was published in the Journal of Infectious Diseases.