Overview

Acute flaccid myelitis (AFM) is a rare but serious condition that affects the spinal cord. It can cause sudden weakness in the arms or legs, loss of muscle tone, and loss of reflexes. The condition mainly affects young children.

Most children have a mild respiratory illness or fever caused by a viral infection about one to four weeks before developing symptoms of acute flaccid myelitis.

If you or your child develops symptoms of acute flaccid myelitis, seek immediate medical care. Symptoms can progress rapidly. Hospitalization is needed and sometimes a ventilator is required for breathing support.

Since experts began tracking acute flaccid myelitis following initial clusters in 2014, outbreaks in the United States have occurred in 2016 and 2018. Another outbreak is expected in 2020. Outbreaks tend to occur between August and November.