AFM Cases and Outbreaks
As of February 28, 2020, there have been no confirmed cases in 2020. There are 17 reports of patients under investigation (PUIs) for 2020.
There were 42 confirmed cases in 2019 out of 141 PUIs. CDC, state, and local health departments are still investigating some of the PUIs.
There have been 613 confirmed cases since CDC began tracking AFM in August of 2014. CDC has been thoroughly investigating cases since that time. We have seen increases in AFM cases, mostly in young children, every two years.
No deaths were reported during the acute illness of patients with confirmed AFM who had limb weakness onset in 2018 and 2019; however, there were two reports of patients confirmed with AFM in 2018 who died months after limb weakness onset. We have also learned of deaths in cases confirmed in previous years.
Annual maps represent only cases for whom information was sent to and confirmed by CDC as of February 28, 2020. Patients under investigation are still being classified, and the case counts are subject to change.
We defer to the states to release additional information on cases as they choose.
Most patients had onset of AFM between August and October, with increases in AFM cases every two years since 2014. At this same time of year, many viruses commonly circulate, including enteroviruses, and will be temporally associated with AFM.
Confirmed AFM cases by CDC
^ Confirmed AFM cases by CDC from August 2014 through February 28, 2020, with onset of condition by December 31, 2019. Case counts are subject to change.
* The data shown from August 2014 to July 2015 are based on the AFM investigation case definition: onset of acute limb weakness on or after August 1, 2014, and a magnetic resonance image (MRI) showing a spinal cord lesion largely restricted to gray matter in a patient age ≤21 years.
† The data shown from August 2015 to present are based on the AFM case definition adopted by the Council of State and Territorial Epidemiologists (CSTE): acute onset of focal limb weakness and an MRI showing spinal cord lesion largely restricted to gray matter and spanning one or more spinal segments, regardless of age.
For more information, visit the Case Definitions page.
It is currently difficult to interpret trends of the AFM data. Collecting information about PUIs for AFM is relatively new. There may initially be more variability in the AFM data from year to year, making it difficult to interpret or compare case counts between years.