Similar to other diseases, case definitions for AFM have specific criteria that we use to classify patients’ cases as being a confirmed, probable, or suspect case of this illness. If a patient’s case does not meet these criteria, it is classified as “not a case” of AFM. By focusing on patients with the most similar symptoms (confirmed cases), we can better compare them to understand possible risk factors for and causes of AFM. Even though some patients’ cases might not meet the case definitions, the information provided about their case still helps us understand the full spectrum of the illness. As we learn more about AFM, we will work with our partners to refine the case definitions. The case classifications are not the same as a diagnosis from a doctor, and should not change treatment or patient care.