Many Americans don’t know much about hepatitis C, but the U.S. Centers for Disease Control and Prevention (CDC) reports that annually, more Americans die from the infection than from causes related to HIV.

Researcher John Ward, MD, director of the division of viral hepatitis at the CDC, told WebMD, “The decrease in deaths from HIV reflects the infrastructure that’s been set up to make access to highly effective treatments happen.”

Both the hep C virus and HIV can be spread through contact with contaminated blood, most often when needles are shared during illegal drug use. Since the nation’s blood supply wasn’t screened for hep C until 1989, experts believe many baby boomers who had blood transfusions when they were younger may have the disease and not even know it.

In fact, most people don’t know they have hep C until decades after being infected — often when routine blood tests find the liver damage the virus has caused over time.

Left untreated, hepatitis C can lead to liver cancer, so many doctors have urged baby boomers to be tested — especially because two new drugs approved for U.S. use last year have been highly effective in eliminating the virus in people with less-advanced liver disease when used with traditional treatments.