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Herpes, the virus that causes cold sores, is still very common in the U.S., the latest statistics show.

A herpes cold sore. redhumv / Getty Images

But it’s becoming less common, the National Center for Health Statistics (NCHS) finds. That’s good news, since the virus is incurable and can kill newborn infants.

The herpes virus that causes genital herpes is also becoming less common, the center found.

Just under half, 48 percent, of people aged 14 to 49 have herpes simplex 1, HSV-1, commonly known as the cold sore virus. By age 49, nearly 60 percent of people are infected, the NCHS, part of the Centers for Disease Control and Prevention, found.

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In 2000, more than 59 percent of people over 14 had the virus.

About 12 percent of people aged 14 to 49 have HSV-2, known widely as genital herpes. Only about 7 percent of teenagers are infected, but more than 21 percent of people over 40 are, the survey found.

Both viruses are transmitted by close contact. They thrive in the mucosal membranes — the thin, wet surface found on the lips, inside the mouth and nose, and on the genitals. The virus travels along nerve cells and takes up permanent residence in the body, emerging during times of stress to cause painful blisters.

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But people can transmit the virus even when they have no sores or other symptoms. And condoms do not provide foolproof protection.

Certain antiviral drugs, including acyclovir and valaciclovir, can control outbreaks but they don’t cure the infection.

“HSV-2 is a lifelong and incurable infection that can cause recurrent and painful genital sores and can make those infected with the virus two-to-three times more likely to acquire HIV, the virus that causes AIDS,” the CDC says on its website about herpes.

People can transmit herpes by kissing and through sex. Some newborn babies in certain Jewish communities have died from herpes infections passed along by ultra-Orthodox practitioners who use their mouths in circumcising infant boys.

Newborns can also catch either virus from their mothers during birth. Taking an antiviral before delivery can reduce that risk.