HIV screening has become more routine, but scientists say people are still falling through the cracks.

HIV specialists say there have been small gains, but no more than 100 of the country's 5,000 emergency rooms routinely test for the virus in patients who aren't critically ill. The Centers for Disease Control and Prevention estimates that 20 percent of Americans infected with HIV don't know they have it.

The specialists say part of the problem is physician confusion about the ease of today's tests. They can cost as little as $15.

More than two years ago, the CDC recommended routine HIV screening for everyone aged 13 to 64, whether they think they're at risk or not.