The virus that causes cold sores, Herpes simplex virus type one, is the most common cause of new genital herpes infections in UW-Madison students, a new study shows.

The findings were reported Monday 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 said. “The typical situation is when a partner has oral herpes [cold sores].”

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

In 2001 the virus accounted for 78 percent of herpes infections of UW students. The study notes that it was more common in females than males and more common in ages 16-21 than older ages. However, increases were noted in all subgroups.

Roberts speculated that changing sexual practices may contribute to this change, particularly oral-genital sexual contact. The increase in use of condoms for vaginal intercourse may also be a factor. Roberts said he believes counseling 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 said.