When it comes to preventive screenings, the Centers for Disease Control and Prevention wants baby boomers to add one more item to the list.

The CDC is calling for all Americans born between 1945 and 1965 to be tested for the Hepatitis C virus as part of expanded recommendations to limit related illnesses and deaths that were released today.

Hepatitis C currently affects more than 3.2 million Americans and is the leading cause of liver transplants and liver cancer in the country. Baby boomers are by far the most vulnerable population, with more than 75 percent of infections occurring within the group, according to a statement.

Since the virus is transmitted through blood, people at risk include those exposed to intravenous drugs, shared needles, blood transfusions and transplants, and unprotected sexual activity. Previous CDC guidelines were focused on identifying those at risk, rather than increasing overall screening.

“It has been overlooked – and I think that the evidence is in the individuals with unrecognized cases,” said Dr. Andrew Talal, a physician at Weill Cornell Medical Center, researcher at the Center for the Study of Hepatitis C, and an external advisor for the agency’s recommendations.

Among the reasons boomers find themselves at higher risk is the fact they came of age during an era marked by experimental drug use. Many are reluctant to divulge past drug experiences because of the stigma. But it’s not just this factor that’s in play — the protocol for blood transfusions and transplants has changed and improved over time, so those who treated in previous years had higher exposure to infection.

Because approximately 80 percent of people with the virus do not exhibit any immediate symptoms, many are not tested for years. But the majority of people affected develop chronic diseases like cirrhosis, according to the World Health Organization –- conditions that the CDC said could be prevented with screening and treatment.

“The earlier the treatment is provided, the more effective it will be,” said Dr. John Ward, director of the division of viral hepatitis at the CDC, in a teleconference on Thursday.

Ward said one-time testing could identify an additional 800,000 people infected with Hepatitis C, and when followed by treatment, could prevent more than 120,000 deaths.

CDC Director Dr. Thomas Frieden said testing for Hepatitis C is generally available in primary care clinics, and is usually covered under routine prevention screenings at little extra cost to the public. The agency will continue to promote its recommendations in the “Know More Hepatitis” campaign.