Study: Cold-sore virus is cause of new genital herpes

Herpes simplex virus type 1 (HSV-1), the virus that causes cold sores, is the most common cause of new genital herpes infections in UW–Madison students, says a new study.

These findings were reported today at the National STD Prevention Conference in San Diego by University Health Services epidemiologist Craig Roberts and Wisconsin State Laboratory of Hygiene epidemiologist John Pfister.

“These findings are significant because they suggest that the majority of new genital herpes infections in UW–Madison students may be acquired from oral sex,” Roberts says. “The typical situation is when a partner has oral herpes (cold sores).”

HSV-1 is usually thought to cause less than 30 percent of genital herpes infections in the United States. The study shows evidence that the proportion of newly diagnosed genital herpes infections due to HSV-1 has increased steadily during the past nine years.

In 2001, HSV-1 accounted for 78 percent of genital herpes infections diagnosed at University Health Services. The study notes that HSV-1 was more common in females than males, and more common in ages 16-21 than older ages. But increases were noted in all subgroups.

Roberts speculates that changing sexual practices may contribute to this change, particularly oral-genital sexual contact. The increasing use of condoms for vaginal intercourse may also be a factor. Roberts says he believes that counseling messages for patients should emphasize the risk of oral sex as a mode of transmission for genital herpes.

“Many students are not aware of this risk and the connection between cold sores and genital herpes,” Roberts says.