Cases of the infection -- a leading cause of liver damage and cancer -- have been dropping across the general population, but they started rising in youth aged 15 to 24 between 2002 and 2006, a trend that continued through 2009, a team from the Massachusetts Department of Public Health reported.
"Of cases with available risk data, injection drug use was the most common risk factor for HCV transmission," the team wrote in the U.S. Centers for Disease Control and Prevention's weekly report on death and disease.
"The increase in case reports appears to represent an epidemic of HCV infection related to IDU (injected drug use) among new populations of adolescents and young adults in Massachusetts," they wrote.
The CDC said in an editorial is had been documenting cases of Hepatitis C infection for decades, but it called the recent epidemic among adolescents and young adults and its apparent link to IV drug use "a disturbing trend."
"Law enforcement data suggest this trend might be occurring in other states," the CDC said, citing data showing increases in first-time heroin use, which jumped to 180,000 in 2009 from 100,000 in 2002.
Law enforcement reports from officials in the Great Lakes, Mid-Atlantic, New England, New York/New Jersey, Southeast, and West Central regions also suggests that heroin use is increasing, particularly among younger users.
Hepatitis C, an infection caused by a virus that attacks the liver, is considered one of the most serious of the hepatitis viruses. It is commonly passed through contaminated blood -- often through needles shared during illegal drug use.
The latest cases were reported from across Massachusetts, mostly among non-Hispanic whites, and were split evenly between males and females.
Of 1,196 cases in which doctors had a history of potential risk factors, 72 percent were in people who reported current or past injection drug use.
Among the 719 people who said they injected drugs in the preceding 12 months, 85 percent said they had used heroin, 29 percent had used cocaine, 1 percent had used methamphetamine and 4 percent had used other drugs.
They said the study suggested the need for better monitoring of Hepatitis C infection and better prevention efforts targeting adolescents and young adults, they said.
According to the CDC, 3.2 million Americans are infected. Most people who are newly infected have no symptoms.