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.
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
- the AFM cases were not caused by poliovirus; all the stool specimens from AFM patients that we received tested negative for poliovirus
- increases in AFM cases have occurred every two years between August and November
- non-polio enteroviruses, particularly EV-D68, are likely responsible for the increases in AFM cases
Evidence that points to enteroviruses:
- More than 90% of patients with AFM had a mild respiratory illness 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: July 13, 2020