(NBC) -- As more baby boomers reach their golden years many are learning they've been carrying a potentially fatal virus.
"About one out of every 30 persons born in these years are living with Hepatitis C infection," notes Dr. John Ward, director of the Division of Viral Hepatitis at the Centers for Disease Control.
More than 3 million Americans are infected with Hepatitis C.
One half to three fourths don't know they have it.
That's of major concern to doctors, who say the longer the virus goes undetected the more damage it can cause.
"We want to find Hepatitis C before the patient develops cirrhosis. Cirrhosis means your liver is severely injured, it has a lot of scar tissue, and it's not working the way it's supposed to work," explains Dr. Jose G. Oliva.
In an effort to find these hidden infections the Centers for Disease Control and Prevention now recommends anyone born between 1945 and 1965 have a one-time test for Hepatitis C at their next doctor's visit.
If they test positive effective treatments are available.
"Persons treated with Hepatitis C with the current drugs, over 70% cure their infection," says Dr. Ward.
Doctors say this blood test has the potential to prevent 50,000 case of liver cancer and 100,000 deaths.
Many of the baby boomers who are infected may have experimented with injectable drugs decades ago, or they had a blood transfusion or transplant operation before routine screening for the virus began.
It can also be spread through sexual contact.