Origin of salad-linked outbreak remains a mystery

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 Tuesday, 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. (AP Photo/Centerd for Disease Control and Prevention)LINCOLN, Neb. (AP) — Nearly 400 people across the country have been sickened by cyclospora, a lengthy intestinal illness usually contracted by eating contaminated food. But if you're looking to find out exactly where it came from, you may be out of luck.