One in four US women between the ages of 14 and 59 years is infected with human papillomavirus – a sexually transmitted virus that can cause genital warts and cervical cancer – according to new government figures.

The survey found that around a quarter of teenage girls and half of women in their early 20s carry the virus.

Doctors say that the new findings show that HPV infection is common and that there is a need to vaccinate young girls against high-risk strains of the virus. But some campaigners argue that vaccination should not be encouraged for all girls because it only protects against a small subset of HPV strains.

Telltale DNA

Eileen Dunne of the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, US, and colleagues analysed self-collected vaginal swabs from roughly 2000 women aged between 14 and 59 years. They tested for HPV infection by analysing DNA in the swab samples, looking for genes that belong to the virus.

About 27% of the women tested positive for HPV infection, which equates to around 25 million women in the US, the team says.

More than 2% of the participants tested positive for HPV 16, HPV 18, or both, two strains of the virus known to cause cervical cancer. High-risk strains of HPV are found in 99% of women with the disease.

Dunne’s group also found that around 1% of the women had HPV 6 and/or HPV 11, which are known to cause genital warts.

In 2006, the CDC’s advisory committee on immunisation provisionally recommended the HPV vaccine Gardasil – which protects against types 6, 11, 16 and 18 – for all girls aged 11 or 12.

Kevin Ault of Emory University in Atlanta, who has conducted clinical trials of the vaccine, notes that only 4% of the participants in Dunne’s study already carried one of the four types of HPV that the vaccine protects against. "To me that means that 96% of the women might benefit from the vaccine," which could prevent them from catching the strain, says Ault.

The fact that nearly a quarter of girls between the ages of 14 and 19 years tested positive for HPV "shows how important it is to vaccinate people early", says Rachel Winer of the University of Washington in Seattle, Washington, US.

Natural defences

But opponents of mandatory HPV vaccination programmes for US schoolgirls say that the new findings do not demonstrate that they are needed.

The body naturally clears most HPV infections on its own, including types 16 and 18, says Dawn Richardson, president of Parents Requesting Open Vaccine Education, based in Austin, Texas. The parent group recently held a demonstration against attempts to make the vaccine mandatory for schoolgirls aged 11 and 12 years in the state.

Richardson adds that Gardasil only protects against two of the HPV types that can cause cervical cancer, which means that girls who receive the jab are still vulnerable to other high-risk types of the virus that cause these tumours.

A MYSTERIOUS protein extracted from pregnant women’s urine can slow the progression of an AIDS-like disease in laboratory animals. It can also destroy cells from tumours that afflict some AIDS patients and boost the production of immune cells, virologist Robert Gallo of the University of Maryland in Baltimore told the AAAS.

"We’re still in the early days. We don’t even know what the active component is exactly," says Gallo. "But we may have the basis here for a whole new avenue of AIDS drugs."

The winding route to the discovery started with a chance observation by Gallo and his colleagues while they were studying Kaposi’s sarcoma, a skin cancer that often claims the lives of patients with AIDS. Kaposi’s sarcoma is particularly common in gay men with the disease, and is thought to be triggered by a herpes virus.

A drug designed to combat genital herpes can also reduce levels of HIV in the blood by 70%, a small trial in Africa has revealed. The herpes medication, valacyclovir, also appears to reduce levels of HIV in the genital tract.

The researchers behind the study suggest that valacyclovir, and other herpes drugs, might dramatically reduce the spread of HIV. Philippe Mayaud of the London School of Hygiene and Tropical Medicine, UK, and colleagues recruited 140 women infected with both HIV and herpes in the West African nation of Burkina Faso.

All of the women had high levels of CD4 immune cells, meaning they were still relatively healthy and ineligible to receive antiretroviral HIV drugs under World Health Organization guidelines.

In addition, none of the women had visible symptoms of herpes so they would not normally be given herpes medication such as valacyclovir.

Sustained effect

The researchers gave half of the women valacyclovir and the other half women placebo pills. At the end of three months, copies of HIV in those who received valacyclovir had dropped from 25,000 copies per millilitre of blood to 8000 per millilitre – a 70% reduction.

This is the same effect one would expect if the women had been given an anti-HIV drug such as Zidovudine (AZT), according to Mayaud. Levels of HIV found in the blood of women who received the placebo, by comparison, had increased slightly on average.

Because all of the women were healthy to start with, there was no difference in symptoms during the 3-month period. But Mayaud says that such a dramatic drop in virus particles could potentially delay the onset of AIDS.

"It’s important to know if the effect is sustained over a long period," he adds, stressing the need for long-term studies of valacyclovir’s effect on HIV infection.

Researchers believe that valacyclovir indirectly reduces HIV infection by decreasing copies of the herpes virus. They note that untreated herpes can cause lesions in the genital region, which subsequently attract a type of immune cell that harbours HIV.

Halting spread

Mayaud points out that the women who received valacyclovir also had half as many copies of HIV in their genital tracts compared to those who received the placebo. This also suggests that valacyclovir has the potential to reduce the spread of HIV, he says.

In Africa, between five and nine out of 10 HIV-infected patients are also infected with herpes. In Europe, the figure is between three and seven out of 10.

Lawrence Corey at the University of Washington in Seattle, Washington, US, says this is good reason to explore herpes drugs as a treatment for HIV. "Because so many people in the world are co-infected we should spend more time on that," he told New Scientist.

Mayaud adds that some herpes drugs, such as acyclovir, cost just $40 per year while the triple-drug regimens normally used to lower HIV levels in patients cost anywhere from $150 to $300 per year.

However, it remains unclear whether valacyclovir would offer an additional benefit if taken with a triple-drug HIV treatment.