KS-associated herpesvirus epidemic in San Francisco gay men predates HIV epidemic; oral sex is a likely risk for infection

A high percentage of San Francisco gay men were infected with Kaposi’s sarcoma-associated herpesvirus (KSHV), the virus that causes Kaposi’s sarcoma (KS), in 1978 before the onset of the HIV epidemic, according to researchers at the University of California, San Francisco (UCSF).

“In part because KS was so rare in the US prior to the HIV epidemic, it had been assumed that KSHV infection was also rare before the HIV epidemic. However, we found a high percentage — about one in four — of gay men infected with KSHV before large numbers were infected with HIV,” said the study’s lead author, Dennis Osmond PhD, associate professor in the UCSF department of epidemiology and biostatistics.

“Furthermore, we found that the level of KSHV infection in gay men was remarkably unchanged from 1978 to 1995. This suggests that any prior reports of a decline in KS before the era of highly active antiretroviral therapy (HAART) are not explained by a decline in transmission of KSHV. In fact, when we re-examined available data for a decline in KS, we were unable to confirm the prior reports,” said Osmond.

“We also found a significant decrease in the practice of unprotected anal intercourse among gay men in San Francisco between 1984 and 1995. This likely explains the decline in HIV transmission observed among gay men during this time. However, the frequency of oral intercourse did not change. Because the prevalence of KSHV infection did not change during this time, this suggests that oral intercourse is a more likely route of KSHV transmission than anal intercourse.

Since KSHV is much more commonly present in saliva than in semen, this suggests that the practice of insertive penile-oral intercourse might be most important in the transmission of KSHV,” said Jeffrey N. Martin MD MPH, assistant professor in the UCSF department of epidemiology and biostatistics, who directed the study with Dr Osmond.

The study, published in the 9 January issue of the Journal of the American Medical Association, examined stored serum from three earlier studies of gay men in San Francisco in 1978-80, 1984-85, and 1995-96. The San Francisco City Clinic Cohort, the first study, screened 6,709 gay men between 1978 and 1980. Testing of the serum samples collected in the first six months of 1978 showed 24.9% infected with KSHV and only 1.8% infected with HIV.

The percentage of gay men infected with HIV rocketed to 50% while the percentage infected with KSHV was steady at 29.6% in the second study. The San Francisco Men’s Health Study was a population based probability sample of gay men with the serum specimens drawn in 1984 and 1985. In this study, 54% of gay men reported unprotected penile-anal intercourse with one or more partners. The rate of unprotected penile-oral intercourse was just over 60%.

The last study was also a population based probability sample of gay men. The San Francisco Young Men’s Health Study collected serum specimens in 1995-96. The rate of HIV infection dropped to 18% while the rate of KSHV infection was stable at 26.4%. At this time, only 11% of gay men reported unprotected receptive penile-anal intercourse. However, the rate of unprotected penile-oral intercourse remained high, over 80%.