Intravenous drug use is largely to blame for a more than triple increase in instances of hepatitis C in four Appalachian states, a report from the U.S. Centers for Disease Control and Prevention said.

The CDC said between 2006 and 2012, hepatitis C (HCV) infections in the mostly rural areas of Kentucky, Tennessee, Virginia and West Virginia increased by 364 percent. The infection rates were highest among people under the age of 30.

he biggest cause of those infections was intravenous drug use, at 73 percent.

During the same period, hospital admissions for the treatment of opioid dependency increased 21.1 percent in the four states. There was a "significant increase" in the portion of people who said they injected drugs at 12.6 percent.

"Taken together, these increases indicate a geographic intersection among opioid abuse, drug injecting and HCV infection in central Appalachia and underscore the need for integrated health services in substance abuse treatment settings to prevent HCV infection and ensure that those who are infected receive medical care," the report concluded.