Candida albicans is the most common type of yeast infection found in the mouth, intestinal tract and vagina, and it may affect skin and other mucous membranes. If the immune system is functioning optimally, this type of yeast infection is rarely serious. However, if the immune system is not functioning properly, the candida infection can migrate to other areas of the body, including the blood and membranes around the heart or brain, causing serious candida symptoms.