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Study Points to Kaposi's Sarcoma Cause

By Samuel Quintero

January 2001

Evidence suggests that human herpes virus 8 (HHV-8) is the common cause of Kaposi's sarcoma. According to the New England Journal of Medicine, Kaposi's sarcoma appears to be the most common cancer associated with HIV infection among men who have sex with men. Statistics show that in the U.S. alone, 30 to 54 percent of HIV-positive men have detectable antibodies for HHV-8. Recent laboratory results suggest the possibility of HHV-8 infection by mouth-to-mouth contact (kissing).

Preceding studies on Kaposi's sarcoma have indicated that HHV-8 was more commonly found in saliva than in genital secretions. Consequently, a group of researchers at the University of Washington Virology Research Clinic conducted a study to determine the source and patterns of HHV-8 shedding (spread/transmission) among men who have sex with men but who are not diagnosed with Kaposi's sarcoma.

Two groups of men who have sex with men (MSM) were recruited for the study. Between 1998 and 1999, samples were obtained from a cohort of 112 men to identify the sites of HHV-8 infection among seropositive men. Among the 112 men, 18 percent tested HIV-positive and 35 percent were seropositive for HHV-8. From the 39 qualified individuals, 27 agreed to participate in the HHV-8 study.

Overall, HHV-8 was detected in oral cavity secretions, semen, prostatic secretions and urethra swabs. HHV-8 was detected significantly more often in oropharyngeal samples (oropharynx) than in genital tract samples. Results showed that oral-cavity secretions had both the overall highest frequency of HHV-8 DNA and the highest number of copies of HHV-8 DNA.

Researchers were also able to detect shedding of HHV-8 in mucosal sites in 60 percent of the total number of men who have sex with men whom were studied extensively. Among the 92 men enrolled in the cohort and who tested negative for HIV, a history of sex with a partner who had Kaposi's sarcoma, deep kissing with an HIV-positive partner, and the use of amyl nitrate capsules ("poppers") or inhaled nitrites were independent risk factors for infection with HHV-8.

In addition to being common among men who have sex with men in the United States, human herpes virus 8 is seen in high rates in regions of Africa and Italy. Since the seropositivity for HHV-8 is commonly first detected during childhood in Africa and southern Italy, the non-sexual modes of transmission may also be important for these regions.

Sexual activity among men who have sex with men plays an important role in the acquisition of HHV-8. Although researchers of the study at the University of Washington focused on the genital tract as the most likely source of HHV-8 shedding, latest results indicated that oral cavity is an important, if not the main source of the infection. Laboratory findings suggest that HHV-8 infection may occur by mouth-to-mouth contact, especially if the seropositive sexual partner has high levels of HHV-8 and high frequency of viral shedding. Furthermore, scientists indicated that oral contact might not be sole mode of transmission; thus, their findings appear to be consistent with previous studies associating increased sexual activity, including oro-genital contact, with the acquisition of HHV-8. Some observations were drawn in response to potential questions regarding the mode of transmission of the human herpes virus 8. If the transmission of the HHV-8 may occur by kissing, why is the infection in North America restricted to men who have sex with men? Conducted studies on the transmission of human herpes virus 8 (HHV-8) lead to suggest that infection may not be easily transmitted and it may depend on the degree of exposure to infected persons, especially to HIV-infected individuals.

HHV-8 is a severe infection in HIV-positive individuals and Kaposi's sarcoma ultimately develops in over 39 percent of those infected with both viruses. Conducters of the HHV-8 shedding study concluded that since mouth-to-mouth contact is not considered a high-risk behavior for sexually transmitted diseases, few men who have sex with men practice protected oral sex. Then, until there is a better understanding of the modes of transmission, it is very difficult to promote the most effective approach in prevention.

The study concluded that safer sex practices, such as consistent use of condoms, although important in preventing other sexually transmitted infections, may not protect against the human herpes virus (HHV-8) infection.

Samuel Quintero is a treatment advocate in AIDS Project Los Angeles' Health Education Core. He can be reached by calling (323) 993-1664 or by e-mail at

This article has been reprinted at The Body with the permission of AIDS Project Los Angeles (APLA).

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