What Is It? Bacterial vaginosis (BV) is a condition in which the normal balance of bacteria in the vagina is disrupted and replaced by an overgrowth of certain bacteria. Symptoms may include discharge, odor, itching or irritation, but often there are no symptoms. Bacterial vaginosis (BV) is the most common of three vaginal infections that fall under the category known as vaginitis. The other two infections are trichomoniasis, a sexually transmitted disease, and the fungal infection commonly known as a yeast infection.