Results of this study are made even more troubling by recent numbers from the Joint United Nations Programme on AIDS showing women to be the fastest growing HIV-positive population segment. In terms of medical research, women are often considered to be at a disadvantage; most tests and studies are conducted using male subjects and resulting medical advice or treatment is not necessarily suited to women. This vulnerability is compounded by the fact that women are more likely to be infected by HIV during heterosexual sex than their male partners. Add Monday's announcement to this already grim tally sheet, and it looks as if women are in for an unforgiving battle against HIV and AIDS. "The HIV virus is like a moving target for scientists," says Gorman. "And now, it could represent multiple moving targets in infected women."
The HIV virus, one of science's most mysterious predators, became even more evasive Monday with news that the virus may infect women and men in different ways. While tracking heterosexual men and women in Kenya, researchers from the Fred Hutchinson Cancer Research Center in Seattle found that female subjects were infected by multiple versions of HIV, while men were infected by a single variant of the virus. The study, published Monday in the journal Nature Medicine, showed that although the women participants had been infected by a single partner, they carried several strains of the virus just after contracting HIV. That could mean that a single strain from a male partner mutates in some unknown way to become multiple strains in infected women. "Assuming these results can be reproduced, this is bad news for vaccine development," says TIME medical writer Christine Gorman. "Single-strain HIV is already a highly variable virus that mutates quickly" and is difficult to pin down.