Public health agencies and drug treatment centers across the U.S. are scrambling to battle an increase in cases of hepatitis C, which they believe relates at least in part to a surge in intravenous heroin use.

Authorities are launching or considering needle exchange programs but are often challenged by geography, as many cases are in rural areas, and the cost of treatment.

Nationwide, the number of cases of acute hepatitis C grew 273 percent from 2009 to 2013, the Centers for Disease Control and Prevention reported in its most recently available statistics. Tracking similarly is heroin use; the CDC reported that the number of users nationwide rose nearly 150 percent from 2007 to 2013 and that use of the drug also more than doubled among ages 18 to 25 in the decade that ended in 2013.

More than 19,000 people died from hepatitis C in 2013, up from 16,235 in 2009, according to the CDC.

Although the agency hasn't established a causal link between individual hepatitis C outbreaks and injected drug use, it notes that injected drug use is the primary risk factor for hepatitis C infection in this country.

Maine is undergoing its worst outbreak of acute hepatitis C since it started to record cases in the 1990s. But the problem is not limited to Maine:

- Madison County, Indiana, had 70 new cases of hepatitis C in 2013, followed by 130 in 2014.

- In Massachusetts, cases of acute hepatitis C grew from 10 in 2009 to 174 in 2013.

-Kentucky leads the nation in the rate of acute hepatitis C, with 5.1 cases for every 100,000 residents, more than seven times the national average, according to 2013 data from the CDC.

Hepatitis C, which can result in liver failure, liver cancer and other serious complications, is the nation's most common blood-borne infection. About 3 million Americans are infected, according to federal statistics. It presents as either acute, or short-term, and chronic, which can last a lifetime.

Both forms are most closely linked to needle-sharing, although hepatitis C is less commonly spread through unprotected sex or other contact with infected blood.

Many local health agencies and health care providers have made the connection and are allowing users to turn in dirty syringes in exchange for clean ones. But many states disallow the practice and federal funding for it is banned.

New treatments are available, but they're expensive and out of reach of most of the rural poor who make up the ranks of the infected. For instance, Harvoni, the leading drug to treat hepatitis C, costs more than $1,300 per pill.

Even so, the number of prescriptions filled for hepatitis C drugs more than doubled to a monthly average of 48,000 during the early part of 2015.