However, the CDC estimates the true number is much higher-- about 34,000 new infections nationally for 2015 -- since hepatitis C has few symptoms and most newly infected people do not get diagnosed.
"Recent CDC research has identified increasing injection drug use -- tied to the US opioid epidemic -- in rural and suburban areas across the country," said Dr. John Ward, an author of the new report and director of the division of viral hepatitis at the CDC.
He said hardest hit areas in terms of new infections are parts of Appalachia and rural areas of the Midwest and New England. Rural areas in other states are also experiencing a similar, though smaller rise in new hepatitis C cases.
Seven states -- Indiana, Kentucky, Maine, Massachusetts, New Mexico, Tennessee and West Virginia -- have rates at least twice the national average, CDC researchers found. In addition, 10 states have rates above the national average: Alabama, Montana, New Jersey, North Carolina, Ohio, Oklahoma, Pennsylvania, Utah, Washington and Wisconsin.
"These new infections are most frequently among young people who transition from taking prescription pills to injecting heroin, which has become cheaper and more easily available in some cases," said Ward. "In turn many -- most, in some communities -- people who inject drugs become infected with hepatitis C."
Hepatitis C, a blood-borne virus, has primarily been transmitted from person to person via shared needles since the early 1990s, when donated blood screening and other precautions were put into place to prevent health care related spread, said Ward.
"Much less frequently, hepatitis C is also transmitted through sexual contact or during pregnancy between a mother and baby," Ward said.
There is no vaccine for hepatitis C. The best way to prevent hepatitis C is by avoiding behaviors that can spread the disease, especially injecting drugs, according to the CDC
Ward and his colleagues believe states can reduce the number of people risking a hepatitis C infection by adopting laws and policies that would increase access for IV drug users to services intended to prevent and treat the infection.
For the new report, then, Ward and his colleagues assessed state laws and Medicaid policies that impact IV drug users.
To decide whether a state had comprehensive needle laws, the CDC explored five questions: Did the state explicitly authorize a needle exchange program? Did the state exempt syringes from the definition of drug paraphernalia? Did the state decriminalize possession and distribution of needles for participants of needle exchange programs? Did the state permit a person to disclose possession of a needle to an arresting officer to avoid criminal prosecution? Finally, did the state allow the sale of needles, without prescriptions, to injected drug users?
With regard to Medicaid, the researchers looked at whether a state imposed sobriety requirements on drug users before approving treatment for an infection. Permissive Medicaid treatment policies, as defined by the CDC, would mean states either do not require a period of being sober or only require screening and counseling for a person to receive treatment.
The CDC found three states -- Massachusetts, New Mexico, and Washington -- with both comprehensive laws and permissive Medicaid policies capable of improving access to preventive and treatment services for injected drug users. All three states, Massachusetts, New Mexico, and Washington, are among those with the highest rates of new infections.
"Even though certain states may have the most comprehensive policies providing access to [syringe service programs], they still may experience steep increases in cases," said Ward, adding that some states changed their policies only recently to address increasing rates.
This appears to be the case with five states: Massachusetts, New Mexico, North Carolina, Pennsylvania, and Washington. Though they have adopted permissive Medicaid treatment policies, they still rank among the 17 states with highest rates of new hepatitis C virus infections.
"The rise in hepatitis C among women of reproductive age and pregnant women parallels this opioid epidemic," said Ward. "And as hepatitis C has increased among young women, the newest generation of Americans are now at risk."
Hepatitis C transmission to infants
Between 2009 and 2014, rates of hepatitis C virus infection among US women giving birth doubled, according to a second CDC study
"In 2014, 35 infants a day were exposed to the virus," said Dr. Stephen W. Patrick, author of the study and assistant professor of pediatrics and health policy at Vanderbilt University School of Medicine. He explained the risk of transmission from mother to infant is estimated to be just about 6%, but research suggests follow-up on infants is poor.
"My worry is that some infants will convert to having hepatitis C without anyone knowing, or treating the infant," said Patrick.
For their study, he and his colleagues used birth certificate and hospital billing data to analyze trends in the rates of hepatitis C infection among women giving birth during the years 2009 through 2014.
Hepatitis C infections present when pregnant women delivered their babies increased 89% during the study period -- from 1.8 to 3.4 per 1,000 live births. In 2014, the highest infection rate -- 22.6 per 1,000 live births -- was in West Virginia, while Tennessee had 10.1 per 1,000.
"Our study found substantially higher rates of HCV among pregnant women in rural and Appalachian counties in Tennessee," said Patrick.
Diving deeper, Patrick and his colleagues examined individual features associated with hepatitis C infection in Tennessee.
They found the odds of an infection were about three times higher among women residing in rural counties than among women in large urban counties, 4.5-times higher among women who smoked cigarettes during pregnancy, and nearly 17-times higher among women with concurrent hepatitis B virus infection.
The study was not designed to determine the exact cause of the increase in hepatitis C among pregnant women or why it has disproportionately impacted rural areas, explained Patrick.
"We suspect it is linked to the ongoing opioid epidemic in the US," said Patrick, explaining his team previously found a 5-fold increase in infants having opioid withdrawal after birth with newborn opioid withdrawal occurring at higher rates in rural areas.
"As the opioid epidemic has continued to evolve, there has been an uptick in heroin and now fentanyl-related complications," said Patrick. "Heroin is generally injected and this comes with a risk of HCV and HIV."
Stemming the tide
Dr. Raymond Chung, a member of the committee of the American Association for the Study of Liver Diseases that provides hepatitis C treatment guidance to doctors, said there are several impediments to treating the drug-using population.
First, it's simply difficult to identify and then treat people who inject drugs, said Chung, who did not participate in the CDC research.
"All too often these persons have fragmentary or fleeting interactions with health care and never do quite make it back to have diagnosis either made or confirmed and more import, to have a care plan outlined," said Chung.
Second, there's a lack of accessibility to the treatments themselves due to limitations on reimbursement of payment for medications to treat the virus. While Medicaid-based payors are frequently footing the bill for IV drug users, reimbursement restrictions vary within states and between states. "So the ability to access those medications is highly variable," said Chung.
Currently there are a number of FDA-approved regimens "and the beauty is that these regimens are now virtually uniformly successful" in bringing about a cure of the infection, said Chung.
When they first appeared on the market, these treatments made headlines and garnered criticism for their high price tags. Today, the price of these treatments generally range from about $60,000 to $90,000 for a standard 12-week course of treatment. However, Chung says deals and different arrangements between the pharmaceutical drug providers and payors have been made considerably reducing the cost.
With treatment for hepatitis C, there must also be counseling to get these patients into care for their addiction to avoid an "exercise in futility" by treating only "a consequence of the substance use disorder." according to Chung.
Coordinated effort is needed to get patients plugged into care so they beat their addictions and avoid becoming reinfected with hepatitis C.
Yet there have been several studies performed on rates of reinfection among IV drug users and they range from about 10% to 20%, said Chung. The results are not yet "water-tight," said Chung, but reinfection rates can be viewed from another angle: "Success can be had -- and durable success can be had -- in most of these patients."