Sex May Transmit
AIDS-Related Cancer Virus
NEW YORK (Reuters Health) - The cancerous skin lesions known
as Kaposi's sarcoma are closely related to HIV/AIDS, but the virus
that causes Kaposi's was prevalent among US gay men before the
HIV epidemic ever started, California researchers report.
Their study also revealed that far into the HIV era in San Francisco--when
more men were practicing safe anal sex but largely not protecting
themselves during oral sex--the Kaposi's-associated virus remained
They speculate that transmission routes other than anal sex,
including oral sex, may be key in the spread of the cancer-causing
virus, called Kaposi's sarcoma-associated herpesvirus (KSHV).
``We think the data strongly suggest that avoiding unprotected
anal intercourse is not enough to avoid acquiring this viral infection,''
the study's lead author, Dr. Dennis H. Osmond, told Reuters Health.
However, he added, this study cannot establish that definitively
because it did not look at each man's individual sexual behavior
and his risk of KSHV infection.
Osmond, a researcher at the University of California, San Francisco,
and his colleagues report the findings in the January 9th issue
of The Journal of the American Medical Association.
KSHV, also known as human herpesvirus 8, is believed to be necessary
for Kaposi's sarcoma to develop. In most healthy people the virus
is unlikely to lead to Kaposi's sarcoma, but the immune system
damage caused by HIV makes infected individuals vulnerable to
Because of the cancer's close relationship to HIV and AIDS, experts
have suspected that the HIV epidemic triggered the similar one
seen with KSHV infection.
But in looking at blood samples from homosexual men involved
in three San Francisco studies from the late 1970s to the 1990s,
Osmond's team found that KSHV was prevalent when HIV infections
were still ``close to zero.'' What's more, it remained stable
over the two decades--even after both HIV prevalence and unprotected
anal sex dropped substantially among men in the study.
From 1978 through 1980, the researchers report, about 28% of
the men were positive for KSHV. That percentage held steady through
1996, when about 26% of men had the virus. Yet during the same
period, HIV prevalence varied greatly, peaking in the mid-1980s
at nearly half of men in one study, then declining to around 17%
among men in another study in the early-1990s.
In addition, the proportion of men reporting unprotected anal
sex fell from more than half in the mid-80s to 11% in 1993, according
to one study the researchers analyzed.
On the other hand, unprotected oral sex remained common throughout
the study periods, ranging from 60% to 90%.
``The inference,'' the researchers write, ``is that behaviors
remaining highly prevalent during this period, such as unprotected
penile-oral intercourse...seem more likely transmission routes
However, Osmond's team points out that there is ``no consensus''
on how KSHV is typically transmitted among gay men, and this study
cannot answer that question.
They speculate that KSHV--an apparently ``ancient virus''--may
have long been endemic among homosexual men without being noticed.
In the US, they note, KSHV-infected people without HIV rarely
develop Kaposi's sarcoma.
Osmond pointed out that the cancer has seen a recent decline
in the US HIV-positive population. Some, he said, have suggested
that this might be due to a decline in KSHV transmission--a belief
that seems to be wrong based on these findings.
Instead, Osmond said, the decline in Kaposi's sarcoma appears
to be the result of patients' better immune function since the
introduction of powerful drug ``cocktails'' containing protease
SOURCE: The Journal of the American Medical Association 2002;287:221-225.
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