Hepatitis C remains the most deadly infectious disease in the United States.
Officials at the Centers for Disease Control and Prevention (CDC) that the number of hepatitis C infections reported to their agency has tripled over the most recent five-year reporting period.
They added the number of hepatitis C infections has reached a 15-year high.
There were 2,436 new hepatitis C cases reported to the CDC in 2015. That compares with 850 cases in 2010.
However, CDC officials note that hepatitis C has few symptoms, so nearly half the people infected with the virus don't know they have it. They add that many people also don't report the infections.
Given that, the CDC estimates there were actually about 34,000 new infections in the United States in 2015.
In addition, deaths from hepatitis C are now hovering at around 20,000 per year. There were slightly more than 11,000 deaths in 2003. The majority of deaths are people 55 years and older.
Baby boomers, drug users
CDC officials estimate that 3.5 million Americans are currently living with hepatitis C.
The majority are the baby boomers, born between 1945 and 1965. CDC officials said that members of this generation are six times more likely to be infected with hepatitis C than other age groups. They are also more likely to die from the virus.
Many have been unknowingly living with the disease and have unintentionally passed it on to others.
Some have developed liver cancer and other life-threatening hepatitis C-related diseases, CDC officials said.
However, CDC officials noted that the largest increase in hepatitis C cases is in the 20-to-29 age group. They said this is to an increase in injection drug use associated with the country's opioid epidemic.
The agency said people who inject drugs are another major contributing factor.
The main mode of transmission is from infected blood, most often found on used needles. Personal contact, including kissing and sexual intercourse, rarely results in transmission, according to the .
Shirley Barger, the co-chair of the San Francisco Hepatitis C Task Force, told Healthline last year that there a number of reasons for the continued rise in cases.
The first is that more people are being tested, she said. That's because more medical providers are aware of the need for tests and baby boomers are being encouraged to come in for tests whether they have symptoms or not.
In addition, the newer tests are easier and quicker to administer.
Another reason, Barger said, is the increase in people who are injecting opioid drugs, especially in communities where syringe exchanges and harm reduction programs are limited.
What can be done
CDC officials last year recommended a comprehensive prevention program to reverse the hepatitis C trend.
The program would include regular testing for hepatitis C, rapid links to medical care for people who test positive, access to substance abuse treatment programs, as well as sterile injection equipment.
The agency as well as the U.S. Preventive Services Task Force also recommends testing for people born between 1945 and 1965.
Many people from that age group acquired hepatitis C from blood transfusions they received before 1992, when donated blood was not screened for the disease.
However, according to a story in the New York Times, health experts are optimistic the rise in hepatitis C deaths can be reversed.
They said new drugs introduced since 2014 are reducing the number of people who die from the infectious disease. Many of those drugs cure patients within 12 weeks.
Among the new drugs are Sovaldi and Harvoni. However, those medications cost between $84,000 and $95,000 for 12 weeks of treatment.
“We must act now to diagnose and treat hidden infections before they become deadly and to prevent new infections,” said Dr. John W. Ward, director of the CDC’s Division of Viral Hepatitis, in a press statement last year.
Ward also told The Times his agency hopes to reduce the number of hepatitis C deaths by 15 percent over the next five years.
Barger said educating the public is another key. That includes informing people on how to avoid becoming infected and where to get treatment if they do.
"We may not be able to take it down to zero cases yet, but we can, with concerted effort, really change the trajectory," she said.
This story was originally posted on May 4, 2016. It was updated on May 11, 2017.