What is candidiasis? Candidiasis, commonly called a yeast infection, is an infection caused by a fungal microorganism, most often the fungus Candida albicans. Candidiasis is also known as candida and thrush. It can cause yeast infections in many areas of the body including: Mouth (oral thrush) Vagina (vaginal yeast infection, vaginal thrush) Digestive tract (gastroenteritis) The fungus that causes most cases of candidiasis, Candida albicans, normally lives in the mouth, vagina, and other places in the body. It exists in a certain balance with other microorganisms, including bacteria. However, some factors or conditions may cause an overgrowth of Candida albicans resulting in candidiasis. Candidiasis can also be passed from a pregnant woman to her child during pregnancy or breastfeeding. Candidiasis is treatable in generally healthy people. However, candidiasis is more likely to occur and can be more difficult to treat in people with weakened immune systems due to such conditions as HIV/AIDS, diabetes, or taking steroid medications or chemotherapy. In these cases, complications of candidiasis may become life threatening. Recurring candidiasis infections can also be a symptom of a serious, undiagnosed underlying disease, such as HIV/AIDS or diabetes. Seek prompt medical care for recurring candidiasis infections including vaginal yeast infections or oral thrush.