Sexual History and Epstein-Barr Virus Infection

Epstein-Barr virus (EBV) is a tumorigenic herpes virus that is carried as a persistent infection by more than 90 percent of adults. Most persistently infected people produce EBV in their saliva, and transmission is through close contact. EBV infection generally occurs early in life, often spread among family members, and primary infection with seroconversion usually occurs without clinical illness. In Western countries where the standard of hygiene is high, primary EBV infection may be delayed until early adulthood and causes infectious mononucleosis (IM) in 45-46 percent of cases. IM is a benign lymphoproliferative disease that is common among university students and can cause prolonged illness and fatigue. It is also associated with an increased risk of subsequently developing Hodgkin disease.

Because it is present in saliva, EBV is assumed (without direct evidence) to be spread among young adults through kissing. It is unclear whether the risk among heterosexual individuals is related to age at first sexual intercourse or number of sex partners, and there is no information on whether this route of transmission can cause IM -- a particularly important issue now that vaccines with the potential to prevent IM are being tested. The present study surveyed more than 1,000 new university students to determine the relationship between sexual behavior and EBV infection in this population.

The researchers conducted a cross-sectional study of EBV serologic testing and histories of IM and sexual behavior among 1,006 new students at Edinburgh University. Students were confidentially surveyed on numbers and sexes of partners, age at first intercourse, use of contraception, STDs, and IM.

Overall, 753 students were EBV seropositive, and 253 were EBV seronegative. Of the EBV-seropositive students, 110 had a history of IM; 643 had no such history. Ten EBV-seronegative students said they had a history of IM. EBV-seropositivity was significantly greater among women (79.2 percent) than among men (67.4 percent)and among those who had ever been sexually active (82.7 percent) than among those who had not (63.7 percent).

The researchers found "a highly significant association between sexual intercourse and EBV seropositivity, with a correlation with increasing numbers of sex partners. These data strongly suggest that sexual contact, or a factor closely associated with it, is an important factor in acquisition of EBV during the teenage years. Because EBV has been found in genital secretions from healthy seropositive men and women, direct spread of virus during sexual intercourse is possible. It is very difficult, however, to distinguish between this and transmission of virus by kissing or orogenital contact during sexual intercourse, and, therefore, an indirect association remains a possibility. Our results show more evidence of a reduction in risk with condom use, which would accord with a direct route of transmission, but the results are not clear cut and need repetition. It seems implausible that the association with sexual intercourse could be explained by confounding factors; certainly, there is no known nonsexual etiological factor that could provide such an explanation."

"To reach adult levels of seropositivity in the United Kingdom, ~90 percent of seronegative students will be infected with EBV while at university, and ~45-65 percent of these will develop IM. Therefore, this group could benefit from a vaccine that prevents primary EBV infection," the authors concluded.

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