Scientists held out the hope of a breakthrough in the prevention of HIV/Aids with the results of a study showing that a vaginal gel used by women before sexual intercourse halved the numbers who became infected.

Scientists have been hunting for years for something that will allow women to protect themselves, and the excitement of Aids campaigners will be hard to contain, even though further research is needed to confirm the findings.

The director general of the World Health Organisation (WHO), Margaret Chan, congratulated the scientists. If their results were confirmed by further tests, WHO will work with countries and partners to accelerate access to these products, she said.

A number of large microbicide trials have been run, but all have failed. The success of this one (run in South Africa where one in three young women aged 20 to 34 is living with HIV) is attributed to the use of an anti-retroviral drug called tenofovir – of the sort used to treat Aids – in gel form.

The study, called Caprisa 004, was conducted by the Centre for the Aids Programme of Research at the University of KwaZulu Natal in South Africa. The researchers recruited 889 women between 18 and 40 who were HIV-negative, sexually active and at risk of becoming infected.

Half were given vaginal applicators filled with gel containing 1% tenofovir. The others got something that looked the same but was inactive. Until the end of the trial, nobody knew who was in each group. The women were asked to insert a first dose of gel 12 hours before sexual intercourse and a second dose as soon as possible afterwards, within 12 hours. All were given counselling on avoiding HIV infection and a free supply of condoms.

At the end of a year, the researchers discovered that the gel had halved the numbers of women becoming infected with HIV. After two and a half years, the numbers had dropped, but there were still 39% fewer infections in those women using it. The drop in the numbers protected, they believe, is caused by some women tending to use it inconsistently as time went on, not knowing whether it was in fact having any effect.

Swingers, straight couples who swap sex partners or have group sex, have some of the highest rates of sexually transmitted diseases, Dutch researchers said.

The researchers at the University of Maastricht based their findings on the data on patients seeking treatment in 2007 and 2008 at three sexual health clinics in South Limburg, Netherlands.

During the study period, there were just under 9,000 consultations at the three clinics, in which 12% were identified as swingers.

The study, published online ahead of print in the journal Sexually Transmitted Infections, found swingers were among those with the highest rates of sexually transmitted infections -- young people and gay men.

The combined rates of Chlamydia and gonorrhea were 10% among straight people, 14% among gay men, just under 5% in female prostitutes and 10.4% among swingers.

While other risk groups for sexually transmitted infections, such as young straight people and gay men, are systematically identified at sexually transmitted infections healthcare facilities and provided with appropriate services, this is generally not the case for swingers, the authors said in a statement.

The US Food and Drug Administration hasn't approved a drug that is designed to treat low sex-drive in women.

Flibanserin, also knows as female viagra or pink viagra, was voted down 10-1 by an FDA advisory panel who said that using the drug was not significantly better than using a placebo.

Not convinced of the clinical meaningful benefit of flibanserin, said Paula Hillard, gynecologist from the Stanford University School of Medicine.

Flibanserin was developed by the German Firm Boehringer Ingelheim and was touted to have the ability to provide satisfying sexual events in pre-menopausal women suffering from Hypoactive Sexual Desire Disorder or HSDD.

In response to the drug's web promotion, which began before it the FDA had a chance to weigh in on its effectiveness, Thea Cacchioni of the University of British Columbia labeled the it a thinly veiled marketing campaign filled with bias, misinformation and celebrity endorsement.

Some were more blunt in their evaluation flibanserin, I think it's a scam, said said Leonore Tiefer with the NYU School of Medicine.

Commercially knows as Girosa flibanserin has yet to be approved for sale in any country to date.