Hepatitis C is officially more deadly to U.S. adults than HIV is, according to a new study from the Centers for Disease Control and Prevention. Health experts are quite pleased with the country's falling HIV rates, but warn that these new figures prove the need for expanded screening methods for hepatitis C, a liver disease commonly spread through shared needles. Here, a look at the rise of America's new "silent" killer, by the numbers:

3.2 million

Americans infected with hepatitis C

50

Percent of those Americans who don't know they have the disease

2/3

Ratio of infected Americans who are baby boomers. The spread "has a lot do do with casual needle injection-drug use back in the 1960s, '70s, and '80s," says Amy Norton at Reuters.

1/33

Ratio of Americans born between 1945 and 1964 who have hepatitis C

18,000

New hepatitis C infections per year

75 to 85

Percentage of hepatitis C infections that become chronic, potentially causing "serious diseases like cirrhosis (scarring of the liver) and liver cancer," says Norton.

15,100

Americans killed by hepatitis C in 2007, the most recent year for which data is available

12,700

Americans killed by HIV in 2007

82,000

Estimated deaths that could be prevented if all Americans born between 1945 and 1965 agreed to a one-time hepatitis C screening, according to the CDC. "Most people don't know they're infected with hepatitis C until decades later," says Rita Rubin at Web MD, "when routine blood tests uncover liver damage caused by the virus over time."

$2,900

Cost of screening an adult for hepatitis C

45

Percent of hepatitis C patients who are cured if treated with two generic medicines, interferon and ribavirin

70

Percent of hepatitis C patients who are cured if two recently approved drugs, Incivek and Victrelis, are added to the regimen

$50,000

Cost of the Incivek treatment

$26,000 to $48,000

Cost of the Victrelis treatment

$100,000

Low-end cost of a liver transplant

Sources: Associated Press, Reuters, Web MD