Infectious disease specialists at Jackson, Mississippi’s local Veterans Affairs (VA) medical center are reporting a major increase in hepatitis C virus (HCV) cases among baby boomers receiving care there. Over the last year and a half, 280 locals have tested positive for the liver virus, and doctors are attributing the spike to opioid use, reports.

The Jackson VA began offering both HIV and hepatitis C testing in December 2014 in conjunction with substance abuse treatment. Since then, nearly one in five people tested have been found to have hepatitis C. Of those cases, doctors determined that 25 percent were brand-new and that patients were not aware they were infected.

VA physicians said the spike in hep C was mainly concentrated among baby boomers, those born between 1945 and 1965. Currently, one-time HCV screenings are recommended for all people within that age range, as they constitute the most at-risk group for undiagnosed hepatitis C in the United States.

Risk factors from opioid use, which ultimately drives many to turn to injecting heroin, has also played a major role in Jackson’s burgeoning epidemic. However, physicians said not all cases they screened came from needle injections.