**FILE** In this image provided by the Centers for Disease Control and Prevention, a photomicrograph of a fresh stool sample, which had been prepared using a 10% formalin solution, and stained with modified acid-fast stain, reveals the presence of four Cyclospora cayetanensis oocysts in the field of view. Iowa and Nebraska health officials said on July 30, 2013, that a prepackaged salad mix is the source of a cyclospora outbreak that sickened more than 178 people in both states. Cyclospora is a rare parasite that causes a lengthy gastrointestinal illness. (Associated Press/Center for Disease Control and Prevention)