Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

Acute flaccid myelitis (AFM) is a rare but serious condition. It affects the nervous system, specifically the area of the spinal cord called gray matter, which causes the muscles and reflexes in the body to become weak. This condition is not new. However, the large number of AFM cases reported since 2014, when we first started our surveillance for this condition, is new. The risk of getting AFM varies by age and year. We have seen increases in AFM cases every two years since 2014 and mostly in young children. Still, CDC estimates that less than one to two in a million children in the United States will get AFM every year. Since 2014, most patients (more than 90%) had a mild respiratory illness or fever consistent with a viral infection before they developed AFM. All the stool specimens from AFM patients that we received tested negative for poliovirus. We are working closely with national experts to better understand the possible causes of AFM and update our information on treatment.