Updated

Health officials say only 1 in 4 Americans with the AIDS virus have the infection under control with medications.

Part of the reason is that about 20 percent of those infected with HIV don't know they have it. People can be infected with the AIDS virus for years without developing symptoms.

An infection was once considered a death sentence. But medications that have been available for 15 years can reduce the amount of virus in people’s bodies to low levels.

However, the Centers for Disease Control and Prevention found only a small fraction of those infected are being successfully treated.

Of the nearly 1.2 million people with the infection, about 40 percent are getting medications regularly.

Worse, only 28 percent have the virus under control at low levels.

The CDC report was released Tuesday.

In other HIV news, a trial conducted in Africa of a microbicide gel containing the anti-HIV drug tenofovir has ended because the gel didn’t protect women from contracting the virus, the New York Times reports.

Part of the study — which also looked at whether two different pills protected against the virus — is continuing and data have not yet been released, making it difficult to figure out why, exactly, the gel didn’t appear to work, the paper says.

The Associated Press and The Wall Street Journal contributed to this report.

Click here to read more from The Wall Street Journal.