Maine is experiencing its worst hepatitis C virus (HCV) outbreak since the state began recording statistics on the liver disease in the early 1990s. Health experts attribute the rise in HCV cases to heroin use, the Portland Press Herald reports.

State health department officials report hep C prevalence has more than tripled in Maine since 2013—from nine to 31 cases of acute HCV in one year. Maine’s chronic hep C rate also increased by 25 percent, rising from 1,142 cases in 2010 to 1,425 in 2014.

The state’s Office of Substance Abuse reports that the number of patients seeking treatment for heroin addiction has also more than tripled, as has the number of self-identified heroin users, increasing from 1,400 people in 2012 to 4,218 currently.

Maine’s Centers for Disease Control and Prevention reports that an uptick in drug users sharing needles accounts for a large part of the outbreak. However, an increase in reporting of HCV prevalence in hospitals across the state could also be driving up the state’s statistics.

Along with the Appalachian region, New England has recently become a hotbed for heroin use in the United States, with national media reports showing similar drug spikes in Vermont, New Hampshire and Massachusetts. Many users are young, white and living in rural or suburban areas; they start off with prescription painkillers like Oxycontin or Hydrocodone before switching over to the street drug.

Maine’s health department plans to continue community outreach efforts in five needle exchange locations across the state, and will also be promoting a “no-cost” hep C screening to help quell the epidemic. However, Maine health officials warn HCV treatment options, especially for low-income addicts, remain scarce across the state.