Doctors are not exactly sure why bacterial vaginosis develops. Because it occurs more commonly in people who are sexually active, bacterial vaginosis is considered by some to be sexually transmitted. However, bacterial vaginosis also occurs in people who either are not sexually active or have been in long-term relationships with just one person.
In some women, bacterial vaginosis continues to return after treatment. Scientists don't understand why this happens. In some cases, treating the male sex partner or routine use of condoms may help to prevent this, but these interventions don't always help.
Having bacterial vaginosis may make it easier for you to be infected with HIV if your sexual partner has HIV. If you already have HIV, then bacterial vaginosis may increase the chance that you will spread HIV to your sexual partner.