A study of sexual activities has linked oral sex with a demonstrably higher rate of acquiring herpes simplex virus type 1, one of the most common sexually transmitted diseases in the United States. In the U.S., at least 45 million people aged 12 and older have had a genital herpes infection. The new study, appearing in the journal Sexually Transmitted Diseases, was compiled by University of Pittsburgh researchers. In the past, it was thought that herpes simplex type 1 (HSV-1) infections most often take place above the waist, while herpes simplex type 2 (HSV-2) predominated below the belt. However, recent evidence suggests that HSV-1 also is an important pathogen in genital herpes infections. HSV-1 is more commonly known to cause infections of the mouth and lips (fever blisters or cold sores). "Receptive oral sex and vaginal intercourse were found to be significant risk factors for the acquisition of HSV-1," said Thomas Cherpes, the study's first author.
"Because oral HSV-1 infections are less frequent in childhood and adolescence, future prevention strategies will need to consider increased susceptibility for HSV-1 among young adults, and the important contribution of HSV-1 to the growing genital herpes epidemic."
The study surveyed the sexual behavior of women aged 18 to 30 whose blood samples were tested for HSV-1- and HSV-2-specific antibodies. HSV-1 was found in 38 percent of women aged 20 or younger. During the follow-up period, analysis found that women who had vaginal intercourse had a more than six-fold higher risk of acquiring HSV-1 than sexually inactive women. For those who had only receptive oral sex without vaginal intercourse, however, the risk was even greater, approaching a ten-fold higher risk.
"The low frequency of infection we detected at enrollment is consistent with other research indicating a reduction in HSV-1 prevalence among younger people," said Sharon Hillier, the study's senior author. "As a result, a significant number of young adults are now susceptible to oral or genital HSV-1 infection."
The researchers say this is important because most current research on genital herpes vaccine development focuses on HSV-2. The falling rate of childhood HSV-1 infections is complicating the scenario by leaving larger numbers of young people susceptible to genital infection with HSV-1, particularly since surveys show a high rate of participation in sexual activities that put them at higher risk. "Lifetime prevalence of receptive oral sex among sexually active women is 75 percent," said Dr. Cherpes. "In our group, more than 90 percent of study participants reported a history of such activity."
