New hepatitis C infections tripled in US over the past five years

The US Centers for Disease Control and Prevention (CDC) released new data last week showing that the number of new hepatitis C virus (HCV) infections reported to the agency nearly tripled between 2010 and 2015.

A related study saw a rising rate of hepatitis C among pregnant women – increasing the likelihood of mother-to-child HCV transmission – while another showed that many states are not doing all they could to reduce new infections.

A total of 2436 new hepatitis C cases were reported to the CDC in 2015 from 40 states, up from 850 in 2010, according to preliminary data described in a new HCV surveillance report. The number rose each year during this period. However, a majority of people living with hepatitis C are thought to be unaware of their status, and the CDC estimates that the actual number was around 33,900 new cases – the highest level in 15 years.

Traditionally 'baby boomers' born between 1945 and 1965 have had the highest hepatitis C prevalence in the US. About three-quarters of the estimated 3.5 million Americans living with HCV fall into this age group, which has a sixfold greater likelihood of being infected than people of other ages. Liver disease caused by hepatitis C progresses over time, and a majority of the nearly 20,000 people who died from HCV-related causes were over age 55.

Hepatitis C incidence is increasing most rapidly among young people age 20-29, in association with the ongoing opioid epidemic. White people living in non-urban areas – especially in the Midwest, New England and Appalachia – are most heavily affected.

The new surveillance report also gives estimates for hepatitis A and B.

Although levels fluctuated somewhat over the past five years, the number of reported new cases of hepatitis A virus (HAV) infection in 2015 was almost the same as the 2011 number: 1390 and 1393, respectively. After adjusting for missed diagnoses and under-reporting, researchers estimated the total number of new HAV infections in 2015 to be 2800.

HAV is primarily spread through contaminated food or water and resolves without treatment. A small spike in 2013 was attributed to an outbreak among people who ate imported pomegranate seeds.

New hepatitis B virus (HBV) case reports also fluctuated a bit, with numbers rising from 2903 in 2011 to 3370 in 2015. This included a substantial 21% increase from 2014 to 2015. After adjusting for missed diagnoses and under-reporting, the estimated total number of new HBV infections in 2015 was 21,900.

The CDC estimates that approximately 850,000 people are living with hepatitis B, with about half of chronic infections among Asians and Pacific Islanders, and three-quarters among people born outside the US. HBV is largely transmitted the same way as HCV, but mother-to-child transmission is more common and it can be prevented with a vaccine.

Sharing needles and other equipment for injecting drugs is the predominant risk factor for HCV infection in the US.

As described in the 12 May Morbidity and Mortality Weekly Report (MMWR), CDC researchers assessed state laws governing access to safe injection equipment, as well as Medicaid policies related to hepatitis C treatment in all 50 states and Washington, D.C.

They found that 18 states had not authorised syringe exchange programmes, taken steps to decriminalise possession and distribution of syringes, or allowed for the sale of syringes without a prescription.

In addition, 24 states required a period of abstinence before people could receive antiviral treatment for hepatitis C through Medicaid. This barrier to treatment access also hinders prevention, as people who are cured no longer transmit HCV.

The 17 states with higher than average HCV incidence in 2015 had a variety of laws and policies concerning comprehensive hepatitis C prevention services. Only three of these states – Massachusetts, New Mexico and Washington – support full access to both syringe programmes and hepatitis C treatment for people who inject drugs.

The current opioid epidemic is largely centred in suburban and rural areas with less access to harm reduction services than large cities. A previous CDC study found that 80% of young people with hepatitis C live more than 10 miles from a safe syringe programme.

A second report in the same edition of MMWR revealed that HCV incidence among women giving birth rose from 1.8 to 3.4 cases per 1000 live births – an increase of 89%. In Tennessee, one of the states heavily impacted by the opioid epidemic, HCV incidence rose by 163%, reaching 10.1 per 1000 live births. Rural white women had the greatest burden of infection. White women were about 80% more likely to have hepatitis C than black women, and 70% more likely than Hispanic women.

"By testing, curing and preventing hepatitis C, we can protect generations of Americans from needless suffering and death," Jonathan Mermin, director of CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention said in a statement. "We must reach the hardest-hit communities with a range of prevention and treatment services that can diagnose people with hepatitis C and link them to treatment. This wide range of services can also prevent the misuse of prescription drugs and ultimately stop drug use – which can also prevent others from getting hepatitis C in the first place."