Yeast infections are overgrowths of normally growing fungi in the vagina. When this fungus grows out of control for many reasons including those described below, the vagina becomes inflamed, and a white cheesy discharge results. There is a strong odor, irritation and itching. Naturally occuring bacteria in the body usually control the yeast fungi. Sometimes this balance is upset. At least 75% of women experience a yeast infection at some point in their life.