The new study has linked oral sex and vaginal intercourse with a demonstrably higher rate of infection, particularly in young women, researchers from the University of Pittsburgh report.

Genital herpes is one of the most common sexually transmitted diseases in the North America. One out of five adolescents and adults have had a genital herpes infection.

While there is no cure for herpes, antiviral medications can shorten and prevent herpes outbreaks. Daily suppressive therapy can reduce, but not eliminate, risk of transmission of herpes virus to non-infected partners.

More recent evidence suggests that HSV-1 (herpes virus, type 1) also is an important pathogen in genital herpes infections, especially in younger women. Herpes virus is more commonly known to cause infections of the mouth and lips, often called fever blisters or cold sores.

 

Herpes virus transmission is possible even in the absence of a visible outbreak.

"Receptive oral sex and vaginal intercourse were found to be significant risk factors for the acquisition of HSV-1," said Thomas Cherpes, M.D., an infectious diseases fellow at the University of Pittsburgh School of Medicine and 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."

At the beginning of the study, 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, or 6.8 versus 1.2 cases.

For those who had only receptive oral sex without vaginal intercourse, however, the risk was even greater - 9.8 versus 1.2 cases.

"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, Ph.D., professor in the departments of obstetrics, gynecology and reproductive sciences and molecular genetics and biochemistry at the University of Pittsburgh School of Medicine and the study's senior author. "As a result, a significant number of young adults are now susceptible to oral or genital HSV-1 infection."

"Lifetime prevalence of receptive oral sex among sexually active women is 75 percent," the doctor said. "In our group, more than 90 percent of study participants reported a history of such activity." 

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