More Americans die as a result of hepatitis C infection annually than from HIV-related causes, according to a report released Tuesday by the Centers for Disease Control and Prevention (CDC) researchers.

Hepatitis C killed 15,100 Americans in 2007, accounting for 0.6 percent of all deaths that year, the researchers said in their report, which is published in the Annals of Internal Medicine. That compared with a little over 12,700 deaths related to HIV.

Those numbers are based on death certificates, and almost certainly underestimate the real scope, according to the CDC.

The researcher also found that three-fourths of the hepatitis deaths occurred in the middle-aged, people 45 to 64.

An estimated 3.2 million Americans are infected with hepatitis C, which can lead to liver cancer, Like HIV, hepatitis C is spread through contact with contaminated blood, most commonly through shared needles used with drugs.

Also, as with HIV, the disease can be sexually transmitted, but that is not as common with hepatitis C. Most people don't know they're infected with hepatitis C until decades later, when routine blood tests uncover liver damage caused by the virus over time.