Illustration of a Candida albicans cell in the gastrointestinal tract. Candida albicans is a fungus that is normally present in the gut flora and on the skin and in mucous membranes such as the vagina, mouth, or rectum. The fungus also can travel through the blood stream and affect the throat, intestines, and heart valves. It is the primary cause of yeast infections in humans. Candida albicans reproduce by budding.