Bacterial vaginosis (BV) is the most common vaginal infection in women of reproductive age, and it occurs when there is an overgrowth of certain “bad” bacteria in the vagina.

Bacterial vaginosis is linked to an imbalance in the bacteria that are usually found in a female’s vagina – an imbalance in the vagina’s naturally occurring bacterial flora. However, nobody fully understands why this imbalance occurs. The vagina usually contains mostly good bacteria and few harmful bacteria – bacterial vaginosis occurs when these harmful bacteria grow in numbers. It is not known what role these harmful bacteria play in causing BV.

A female’s vagina should contain lactic acid bacteria called lactobacilli. These bacteria produce lactic acid, making the vagina slightly acidic, preventing other bacteria from growing there. If the vagina is not as acidic as it should be, other bacteria may have the opportunity to grow. If there are fewer lactobacilli, the vagina may become less acidic.

Any female can develop BV. Some behaviours or activities may upset the balance of the naturally occurring bacterial flora and increase the risk of developing BV, including:

• Douching – using water or a medicated solution to clean the vagina
• Having a bath with antiseptic liquids
• Having a new sex partner
• Having multiple sex partners
• Perfumed bubble baths and some scented soaps
• Smoking
• Using an IUD (intrauterine device), such as a contraceptive device made from plastic and copper that fits inside the uterus
• Using vaginal deodorants
• Washing underwear with strong detergents

Symptoms

Women with BV may have an abnormal vaginal discharge with an unpleasant odour. Some women report a strong fish-like odour, especially after intercourse. Discharge, if present, is usually white or grey; it can be thin. Women with BV may also have burning during urination or itching around the outside of the vagina, or both. However, most women with BV report no signs or symptoms at all.