Spermicides May Ease HPV Transmission
Animal Study Shows Ingredient in Spermicides May Boost Transmission of Human Papillomavirus
Next, the researchers focused on the use of carrageenan, a substance widely
used as a thickening agent in foods and also used in some vaginal lubricants,
including the brands Divine No. 9 and BIOglide.
The researchers use pure carrageenan, not the commercial lubricant formulas.
They pretreated one group of mice with the spermicide and another group with
both the spermicide and carrageenan. The third group wasn't pretreated with
anything and wasn't exposed to the virus.
None of the animals exposed to both the spermicide and carrageenan got
infected with HPV, Roberts says. But of those exposed just to the spermicide,
"all were infected," he says.
Exactly how carrageenan protects isn’t certain, either, Roberts say. It may
interfere with the HPV interaction at the cellular level, helping to prevent
infection, he tells WebMD.
"We have no idea whether this is valid in humans," cautions Harper.
Human trials of carrageenan are definitely in order, she says.
HPV and Cervical Cancer
In 2007, more than 11,000 women in the U.S. will learn they have cervical
cancer, according to estimates from the American Cancer Society, and about
3,670 women will die from it this year.
Of the more than 100 HPV types, about 30 or so types can cause genital HPV
infections. Of those, certain types are classified as "high risk"
because they lead to abnormal cell changes and can cause genital cancers. HPV
16 and 18 are high risk -- thought to cause about 70% of all cervical
Most sexually active men and women do contract HPV at some point. Most won't
have symptoms and the virus will typically clear on its own, often within two
years or less. When it doesn't clear, the cells in the cervix can continue to
change abnormally, with precancer or cancer the result if no treatment is
Though the new HPV vaccine, Gardasil, can help prevent infection, and
another HPV vaccine is expected to be available soon, neither is a perfect
solution because they don't protect against all HPV types. For that reason,
Roberts and other public health experts believe it is important to consider
other interventions against HPV to reduce the toll of cervical cancer.
Preventing HPV Infection
More research is needed before any practical advice can be given, Roberts
says. Carrageenan, he says, "has not been studied enough to officially
recommend. It's something I think is worth investigating."
Earlier NIH research, Roberts says, showed that carrageenan is also
protective against some of the other HPV types besides 16. And their research
suggests that when the nonoxynol-9 and carrageenan are used together, the
spermicide is still effective for birth control purposes.
Perhaps, Roberts says, manufacturers of commercial spermicides with
nonoxynol-9 might consider adding carrageenan to the formulas.
"We recommend using condoms without spermicide," says Fred Wyand,
spokesman for the American Social Health Association in Research Triangle Park,
N.C., a nonprofit organization focusing on sexually transmitted disease
information and education.
"There is some evidence that the spermicides can cause inflammation of
the skin, which may make acquisition of sexually transmitted infections more
likely," Wyand says.
If a woman wanted to prevent both HPV infection and pregnancy, Harper says,
she would "probably tell her to use a different birth control method than a
spermicide. She should still use a condom, and if she uses a lubricant, she
could pick one with carrageenan."
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