What CDC is Learning about AFM

CDC has been thoroughly investigating AFM in the United States since 2014, when large numbers of cases were first reported.

Who, When, Where, and What puzzle pieces.

Since 2014, we have learned that

  • Most AFM cases have been in children (over 90%).
  • AFM has occurred in children and adults in 49 states and DC.
  • Increases in AFM cases have occurred in 2014, 2016, and 2018.
  • Non-polio enteroviruses, particularly EV-D68, are likely responsible for the increases in AFM cases in those years.
  • All the stool specimens from AFM patients that we received tested negative for poliovirus. This means that the cases of AFM since 2014 are not caused by poliovirus.

Evidence that points to enteroviruses

  • More than 90% of patients with AFM had a mild respiratory symptoms or fever consistent with a viral infection before they developed AFM.
  • We have seen increases in AFM cases at about the same time of year when enterovirus circulation is most common in the United States.
  • We have detected coxsackievirus A16, EV-A71, and EV-D68 in the spinal fluid of a small number of patients with AFM, which points to the cause of their AFM. For all other patients, no pathogen (germ) has been detected in spinal fluid to confirm a cause.
  • Studies have shown that AFM patients had antibodies specific for enteroviruses in their spinal fluid more often than persons without AFM. Having antibodies for enterovirus means that a person was previously infected with the virus.
Page last reviewed: December 29, 2020