Around the globe, an estimated 2 billion people have been infected with hepatitis, according to new statistics from the World Health Organization – but what’s even more concerning is that most of these people don’t even know they have the liver disease.

That’s because many hepatitis carriers can live for years – even decades – without experiencing any symptoms. Just ask Southern rock legend Gregg Allman of the Allman Brothers Band and R&B artist Natalie Cole.

Cole told FoxNews.com that she was “mortified” when she was diagnosed with hepatitis C after a routine blood test in 2008.

“I found out that it had been living inside my body for over 20 years, which was an extraordinary revelation, because I never felt, you know sick or possibly if I did, I just worked through it,” she said.

Just like Cole, Allman said he had been unknowingly living with the chronic condition for decades, which he thinks he probably got in his 20s. His diagnosis finally came in 1999, but because he had been living with hep C for so long, his treatment failed, and ultimately, he ended up needing a liver transplant.

Allman said he wished things hadn’t gotten to that point, and that’s why he and Cole have teamed up with Merck and the American Liver Foundation to promote the campaign, “Tune In to Hep C,” a national public health campaign to educate people about the disease and the “importance of taking action.”

“If we could save the life of somebody, or if they go and get checked – it's just a blood test, we want them to, you know if you don't go and get checked, you never know you had it, and time is something you don't have. And doing nothing is not an option,” Allman said.

And that’s exactly what the campaign is trying to drive home to people, according to Allman’s Georgia-based physician, Dr. Steve Carpenter, an associate professor of internal medicine at The Center for Digestive & Liver Health in Savannah.

“Again, doing nothing is not an option,” Carpenter said. “This disease is not going to go away. This campaign is about awareness and talking with friends and family about options. We also have to breakdown the social stigma.”

The stigma surrounding the disease is also a huge barrier – but both Allman and Cole are hoping to break down those walls.

“That’s why this campaign is so important,” Cole said. “Because one of the focuses of it is to lift that stigma… to try to get rid of that stigma… because for years, everyone thought, ‘Oh hep C? You're a junkie. You were a junkie or you were a drug addict.’ In my case, that was the case, but it turns out there's several ways you can get hepatitis C.”

Allman said in the beginning he didn’t tell anyone about his diagnosis because he wasn’t sure what people would think, but in the end, he said he was “surprised and grateful” for the support of his friends and family.

“You've got it, so take the next step. You’ve got to go into action with this whole thing, because the sooner you detect it, the sooner you're going to get treatment for it,” he said.

At a benefit concert in New York City Wednesday night, Allman and Cole performed to a sold-out crowd, and in the end, raised more than $250,000 to support testing, awareness programs, and services for people with chronic HCV infection.

The Toll of Hepatitis

Viral hepatitis kills as many as a million people annually across the globe. Here in the U.S., the Department of Health and Human Services estimates that 3.5 to 5.3 million are living with viral hepatitis, with hepatitis C being the most common of all bloodborne infections.

WHO hepatitis specialist Dr. Steven Wiersma told a news conference this week that the disease – which has five main viruses – produced a "staggering toll" on health care systems around the globe and had the potential to spark epidemics, as well as being the main cause of liver cirrhosis and cancer.

As a result, the WHO has declared Thursday the first ever, “World Hepatitis Day.”

Of the five viruses dubbed A, B, C, D and E, a new WHO document says, B was the most common and could be transmitted by mothers to infants at birth or in early childhood as well as through contaminated injections or injected drug use.

The E virus, transmitted through infected water or food, is a common cause of outbreaks of the disease in developing countries and is increasingly observed in developed economies, according to the WHO.

The WHO says effective vaccines had been developed to combat the A and B viruses and could also be used against D. A vaccine for hepatitis E had been developed but was not widely available, while there was none for the C virus.

Vaccination campaigns had scored considerable success in many countries, with about 180 of the WHO's 193 member states now including the B vaccine in infant immunization programs, the agency said.

But more needed to be done to prevent or control the disease. It was vital to ensure that people already infected could be tested and given quality care and treatment without delay, the WHO document declared.

Click her for more information about the campaign “Tune In to Hep C.”

Click here for more information about hepatitis from the WHO.

Reuters contributed to this report.