Results from a new study have added to the evidence that the common vaginal infection bacterial vaginosis (BV) is a sexually transmitted disease. Previous research had linked such risky sexual practices as having multiple partners to BV, but the role of sexual activity remained unclear. But in the new study, scientists found that women who had no sexual experience did not appear to have BV at all, while women who'd had intercourse did have the infection. The percentage of study participants who...