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The bottom line
Is rectal mucus a source of HIV transmission?
by Chuck Osborne
rectal mucus a source of HIV transmission? There have
Isbeen few studies conducted on rectal secretions and HIV
plasma load, but the limited data does point to the probability
that rectal mucus has a higher concentration of HIV than
other bodily fluids such as blood or semen.
Rectal mucus is a natural-forming substance that occurs when
the bowels contract to allow smooth passage of stool. In most people,
this only happens in small amounts. Most rectal mucus discharges
are benign, but there are many conditions that can cause abnormal
or excessive discharge. Amongst these could be hemorrhoids, anal
fissures, prolapses, and warts. Crohn’s disease, colitis, rectal ulcers,
anal tuberculosis, or any number of sexually transmitted infections
(STIs), as well as some AIDS-defining illnesses, could also be responsible.
It’s also normal that rectal mucus can consist of a litany of
fluids, the most evident being blood.
The US Centers for Disease Control and Prevention do not
specifically list rectal mucus as a source of HIV transmission,
and very few other agencies mention this fluid by name; however,
the general reference to vaginal or anal fluids presumably
includes anal mucus.
The US Centers for Disease
Control and Prevention do not
specifically list rectal
mucus as a source of HIV
transmission, and very few
other agencies mention this
fluid by name.
Nevertheless, scientists have been aware that rectal fluids
can be a source of infection since Dennis Osmond’s report
from the University of California, San Francisco, in 1998.
There appear to be only two studies of note that have
attempted to measure levels of viral load in rectal mucus.
The first, conducted in 2000 by investigators at the Center for
AIDS & STD at the University of Washington in Seattle, found
only one man out of 54 participants with blood plasma viral
loads below 50 copies/mL who had detectable HIV virus in
rectal secretions. The other study, conducted in 2004 by
Zuckerman et al, again at the University of Washington,
compared viral loads in the blood, semen, and mucosal lining
of the rectum in 64 gay men in the US and Peru. Viral loads
tended to be higher in rectal mucus.
Bodily fluids and their risk factor
in HIV transmission
HIV is not present in:
• Urine
• Feces
• Vomit
• Sweat
HIV is present in negligible (non-infectious) quantities in:
• Saliva (only detected in a very small number of people)
• Tears
• Blister fluid
HIV is present in sufficient (infectious) quantities in:
• Rectal lubricating secretions (in very high concentrations)
• Blood and blood products
• Semen and pre-ejaculate (pre-cum)
• Vaginal/cervical secretions or juices
• Breast milk
Zuckerman’s study fails to note that of 63 patients, only 27
were on antiretroviral therapy and only 18 had undetectable
viral loads. The study also doesn’t address how long the viral load
was non-detectable before biopsy, or the type of antiretrovirals
participants were taking.
We know from many other studies that some people can have
undetectable viral load in their blood but detectable viral loads in
either genital secretions or sperm. Scientists believe that this may
be more likely to happen in people who have STIs or even
asymptomatic herpes (that is, herpes with no visible symptoms).
The bottom line is that when engaging in anal sex, it’s
always wise to use precautions. 5
Chuck Osborne is a volunteer with BCPWA’s
Prevention and Treatment Information Programs.
8 living5 MayqJune 2010