No lesions? Genital herpes still contagious

People with genital herpes can transmit the virus to partners even when they do not have lesions, new research shows.

This has been suspected before, but "the data here looks really robust," said Fred Wyand of the American Social Health Association.

Herpes simplex virus type 2 (HSV-2) is one of the most common sexually transmitted diseases, affecting 536 million people worldwide. Of U.S. adults, only 10 percent to 25 percent of those infected recognized the disease.

Blood tests to detect HSV-2 became widely available in 1999, making it easier to find out if people have genital herpes, even if the infection isn't active.

Still, previous large government surveys had found that some 80 percent of Americans don't know they have genital herpes, said study co-author Dr. Christine Johnston. The report appears in Wednesday's issue of the Journal of the American Medical Association. -- HealthDay