What is it?
Bacterial vaginosis (BV) is a disease of the vagina caused by an excessive growth of bacteria. Typical symptoms include increased vaginal discharge that has a fish-resembling smell, and burning with urination. Sometimes there might be no symptoms at all.
BV is most common in Africa and least common in Asia and Europe. In the US, about 30% of women between the ages 14-49 are affected.
What causes it?
There lives a number of harmless bacteria inside the vagina. BV happens when the balance of these normal bacteria shifts and one species starts to dominate over the others. One of the main risk factors of BV is rinsing the vagina from inside with water – this is one of the reasons why doing this is discouraged. Having a female partner also increases the risk of BV quite significantly.
What happens during it?
A vagina normally contains lactic acid bacteria, and the lactic acid they produce keeps the vagina slightly acidic and prevents the growth of other bacteria. It is not really understood why the lactic acid bacteria start to die in BV, but they do. The rise in the pH gives a chance to many anaerobic bacteria to grow. These anaerobic bacteria don’t release energy the same way we do – they break down the molecules they’ve found in their surroundings without using oxygen. They produce large amount of enzymes that go on and break down some molecules found inside the vagina. The remains of these molecules are what makes the vaginal discharge smell in BV.
How can it be treated?
BV is typically treated with antibiotics. They can be given by mouth or applied inside the vagina.
Sources: https://en.wikipedia.org/wiki/Bacterial_vaginosis, http://www.uptodate.com/contents/bacterial-vaginosis