The often-undiagnosed virus is transmitted through contaminated blood. While infection rates have dropped dramatically since the early 1990s - due in part to the introduction of blood and organ screening - many older adults are still at risk, according to the U.S. Centers for Disease Control and Prevention, which released the draft guidelines.

According to the CDC, one in 30 baby boomers - the generation born from 1945 through 1965 - has been infected with hepatitis C, and most do not know it.

A one-time, cost-effective blood test would "identify hundreds of thousands of hidden infections," said Dr John Ward, director of CDC's division of viral hepatitis.

He likened the proposal to existing age-related guidelines on screening for diseases including breast cancer, cervical cancer and high cholesterol.

Hepatitis C causes serious liver diseases, including liver cancer - the fastest-rising cause of cancer-related deaths - and is the leading cause of liver transplants in the United States.

The CDC said it believes routine blood tests will address the largely preventable consequences of the disease, especially in light of newly available therapies that can cure around 75 percent of infections.

The field has attracted broad interest with two new hepatitis C drugs - Incivek from Vertex Pharmaceuticals Inc and Merck & Co's Victrelis - reaching the U.S. market in the past year.

Companies including Gilead Sciences Inc and Bristol-Myers Squibb Co aim to improve on those medicines with pills that do not need to be combined with injections of immune system boosters, which have side effects that can deter patients.

More than 15,000 Americans, most of them baby boomers, die each year from hepatitis C-related illness, such as cirrhosis and liver cancer.

Current U.S. guidelines call for testing only individuals with certain known risk factors for hepatitis C infection.

The CDC said it will accept public comment on the draft recommendations from May 22 to June 8.

Final recommendations will be issued later this year.

(Reporting By Deena Beasley in Los Angeles; editing by John Wallace and Matthew Lewis)

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