Barcelona, Spain ? The AIDS pandemic is increasingly becoming one of young women, experts say.

About half of all new infections are in women, and among people in their late teens and early 20s, females account for nearly two-thirds of new cases.

Sex between men and women continues to be the main way HIV is spread in the developing world, where the majority of HIV cases are, and it is difficult for women there to follow prevention recommendations because of their subordinate position in society.

“It is women and girls who are overwhelmingly the casualties of this scourge, and it is getting worse,” said Stephen Lewis, the U.N. secretary-general’s special envoy on AIDS in Africa. “It is a nightmare.”

Scientists at the 14th International AIDS Conference presented several studies on the female face of HIV and on ways to help women protect themselves without having to rely on men to use condoms.

“We’ve got to make sure that the money is going proportionately to those who are paying proportionately the greatest price, and at the moment, the greatest price on this planet is being paid by the women and girls of Africa,” Lewis said.

A University of California, San Francisco, study found that in Zimbabwe, rape is common and negotiating for safe sex to prevent HIV infection is almost impossible for many adolescent girls who become involved with older men in return for clothes and school fees.

The phenomenon of intergenerational sex is driving much of the epidemic in southern Africa, where between one-quarter and one-third of older men are HIV positive, said the study’s leader, Nancy Padian, director of international programs at UCSF’s AIDS Research Institute.

“An intervention to promote economic self-sufficiency is an essential element in any plan to reverse the spread of HIV,” she said.

In some areas, common myths about AIDS that sex with a virgin cures sexually transmitted infections and that sex with condoms will not release body heat also work against women, Dr. Suniti Solomon, director of the YRG Center for AIDS Research and Education in Chennai, India, told the conference.

On average, women are becoming infected 10 years earlier than men due to early marriages, rape or being forced into prostitution for economic reasons, said Solomon, whose team documented the first evidence of HIV infection in India.

There is an urgent need for HIV prevention methods that do not require the cooperation of the male partner, Solomon said.

One possibility is microbicides, gels designed to kill HIV. No microbicide has been shown effective yet, but more than 50 candidates are under development.