Candidiasis, commonly called yeast infection or thrush, is a fungal infection of any of the Candida species, of which Candida albicans is probably the most common.
Yeast organisms are always present in all people, but are usually prevented from "overgrowth" (uncontrolled multiplication resulting in symptoms) by naturally occurring microorganisms.
At least three quarters of all women will experience candidiasis at some point in their lives.
The Candida albicans organism is found in the vaginas of almost all women and normally causes no problems.
However, when it gets out of balance with the other "normal flora," such as lactobacilli (which can also be harmed by using douches), an overgrowth and symptoms can result.