Subjects in this study will be asked to provide a blood, urine, and stool sample when they present with symptoms or either cow milk protein intolerance or eosinophilic esophagitis. Blood will only be obtained if clinical samples are requested, and no extra blood drawing will be required for participation in this study. Similar blood, urine, and stool specimens will be obtained after the patient has been placed on anti-atopic therapy and is experiencing clinical remission.