About 240,000 people in the United States have HIV but don't know it, according to a report Tuesday from the Centers for Disease Control and Prevention.

That amount represents 20 percent of the estimated 1.2 million people living with HIV in the nation, the CDC said.

People who don't know they have the disease won't be able to get care and treatment, will be at grater risk for serious health problems and early death and can give the virus to others without knowing it, the CDC said.

"All Americans between the ages of 13-64 be tested for HIV at least once as part of regular medical care. Others at greater risk (those with more than one sex partner, who inject drugs or are a men who has sex with other men) should get tested once a year or more often." the CDC said in a statement.

Although there are treatments that currently lower the amounts of the virus in the body of a person and improve health and help patients live longer, like the antiretroviral therapy, only half of people with HIV in the U.S. are in care and only 28 percent have their virus under control, the CDC said.