The Department of Defense, in collaboration with the Centers for Disease Control and Prevention (CDC) and the Department of Veterans Affairs, announced today that it has completed and published a peer-reviewed epidemiological study that has found that military personnel are at three to five times lower risk of hepatitis C virus infection than the civilian population. The study is one of the largest epidemiological studies of hepatitis C virus infection ever conducted.
The results, just published last weekend in the "American Journal of Epidemiology," found that among 10,000 active duty personnel, a low percentage (0.5 percent) were found to have been infected with the hepatitis C virus. Men and women had the same rate of infection. Among adults in the general population, 3.7 percent of males and 1.6 percent of females (2.6 percent overall) have been found by the CDC to be infected with the hepatitis C virus.
The research evaluated 21,000 military personnel serving in 1997. Blood samples stored in the DoD Serum Repository were used to test for antibody to hepatitis C virus infection. The study was directed by the Naval Medical Research Center, Silver Spring, Md.
In this study, most hepatitis C virus infections were concentrated in older military personnel. "Among troops less than 35 years of age, only 0.1 percent (1 out of 1,000 troops) had been infected" said Dr. John Mazzuchi, deputy assistant secretary of Defense for Health Affairs. "Likewise, among 2000 military recruits, two (0.1 percent) had previously been infected with the hepatitis C virus."
In addition to general active duty personnel and recruits, the study evaluated 2,000 reservists, 2,000 troops about to retire, 1,000 health care personnel, 1,000 troops who had been serving since before 1974 (the Vietnam War era), and 3,000 over-sampled demographic groups. Importantly, reservists were found to have the same level of hepatitis C virus infection as troops on active duty. Health care personnel and Vietnam era veterans were not at increased risk of infection.
Based on the results of this study, military personnel greater than 34 years of age and separating or retiring from military service are now being offered testing for this viral infection. "Because this age group includes 80 percent to 90 percent of troops with hepatitis C virus infection, we have implemented this program to screen the military population at highest risk," said Mazzuchi. "In addition, we have implemented an extensive program to identify patients who may have been infected with the hepatitis C virus through a blood transfusion before scientific research had developed an accurate test for this disease."
The low risk of hepatitis C virus infection in current members of the military matches findings from the largest epidemiological study of the civilian population. In a study of the general population, the CDC found a lower risk of hepatitis C virus infection among military veterans compared to individuals who had not served in the armed forces.
"The very low level of hepatitis C virus infection in today's military can be attributed to infrequent injection drug use, which is the most common source of hepatitis C virus transmission in the United States," said Mazzuchi. Illicit drug use is rare in the U.S. military because of mandatory drug testing of new recruits and because of random drug testing of military personnel throughout military service.
The "American Journal of Epidemiology" is a journal published by The Johns Hopkins University School of Hygiene and Public Health.