Nov. 8, 2000 -- Deep kisses could spread the virus that causes Kaposi's sarcoma, the deadly cancer linked to AIDS. The new finding, reported in TheNew England Journal of Medicine, suggests that current safe-sex practices may not protect against the virus.
"I wouldn't want this to detract from safer-sex practices, which emphasize prevention of HIV," study co-author Anna Wald, MD, MPH, tells WebMD. "However, we do need to be aware that there are viruses that can be spread through kissing." Wald is medical director of the virology research clinic at the University of Washington in Seattle.
Discovered only six years ago, human herpesvirus 8 (HHV-8) is widely thought to be the cause of Kaposi's sarcoma in people with AIDS. In addition to Kaposi's sarcoma, the virus is linked to tumors of the blood and lymph nodes. Moreover, Italian researchers report in the same issue of NEJM that HHV-8 infection can lead to the destruction of the bone marrow in transplant patients taking immunity-suppressing drugs to prevent organ rejection.
Exactly how HHV-8 is spread has long been a mystery. Among HIV-infected people in the U.S. and western Europe, Kaposi's sarcoma is more common among gay and bisexual men than among heterosexuals. Most experts, therefore, assumed that HHV-8 is spread by anal intercourse. To test this theory, Wald and co-workers tested oral, genital, and anal samples from HHV-8 infected men. To their surprise, they found that the virus was much more likely to be found in the saliva than anywhere else -- and in much larger amounts.
Next, the researchers looked at risk factors for HHV-8 in a group of HIV-negative men. Three things increased the risk of infection:
- Men were 5.4 times more likely to have HHV-8 infection if they reported deep kissing with an HIV-positive partner.
- Men were 4.8 times more likely to have HHV-8 infection if they had a partner with Kaposi's sarcoma.
- Men were 5.1 times more likely to have HHV-8 infection if they used "poppers" or other inhaled nitrites, which are taken to improve the intensity of the experience during sex.
"Fortunately, we think that for most healthy people, this virus will not present any kind of a health problem," Wald says. "It is particularly a problem for people with HIV and people whose immune systems are being suppressed for transplant surgery."
Patrick S. Moore, MD, MPH, who is the co-discoverer of HHV-8, wrote an editorial accompanying the studies in NEJM. "We really don't know the rate of disease among healthy people who become infected, but probably one in a thousand will get KS [Kaposi's sarcoma]," the Columbia University researcher tells WebMD. "But if one of those people becomes immunocompromised, the risk of disease can skyrocket to up to a 50-50 chance. That is the reason why it is a dangerous virus."
Despite its recent discovery, Moore says that HHV-8 has been around for a long time. "Humans have always had this virus -- it evolved along with us and has maintained itself in some small portion of the human population over millions of years," he says. "Chimps have their own version of HHV-8, gorillas have their own -- and some of the lower primates have two versions. Maybe the second one died off. But the other possibility is that it also is present in higher primates -- so there could be an HHV-9. If it were like most herpes viruses, it could be associated with disease."