AFM Cases and Outbreaks

There are 33 confirmed cases in 2019 out of 131 reports of patients under investigation (PUIs). CDC, state, and local health departments are still investigating some of the PUIs.

There have been 603 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 AFM Cases by State

Annual maps represent only cases for whom information was sent to and confirmed by CDC as of January 2, 2020. Patients under investigation are still being classified, and the case counts are subject to change.

AFM Reported Cases 2019

In 2019, there were 33 total confirmed cases in 16 states.

AFM Reported Cases 2018

In 2018, there were 237 total confirmed cases in 41 states. One of the confirmed cases is a foreign resident (based on the country of usual residence) and therefore not included in the state map.

AFM Reported Cases 2017

In 2017, there were 38 total confirmed cases in 17 states.

AFM Reported Cases 2016

In 2016, there were 153 total confirmed cases in 39 states and the District of Columbia.

AFM Reported Cases 2015

In 2015, there were 22 total confirmed cases in 17 states.

AFM Reported Cases 2014

In 2014, there were 120 total confirmed cases in 34 states between the months of August and December. These case counts include only pediatric patients younger than 22 years of age.

We defer to the states to release additional information on cases as they choose.

Cases by Month, 2014-2019

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 reported to CDC: Aug-14 = 21, Sep-14 = 51, Oct-14 = 24, Nov-14 = 15, Dec-14 = 9, Jan-15 = 2, Feb-15 = 2, Mar-15 = 1, Apr-15 = 0, May-15 = 1, Jun-15 = 0, Jul-15 = 2, Aug-15 = 3, Sep-15 = 1, Oct-15 = 4, Nov-15 = 2, Dec-15 = 4, Jan-16 = 1, Feb-16 = 0, Mar-16 = 6, Apr-16 = 1, May-16 = 6, Jun-16 = 9, Jul-16 = 12, Aug-16 = 30, Sep-16 = 44, Oct-16 = 27, Nov-16 = 9, Dec-16 = 4, Jan-17 = 1, Feb-17 = 5, Mar-17 = 5, Apr-17 =4, May-17 =2, Jun-17 = 4, Jul-17 = 3, Aug-17 = 1, Sep-17 = 4, Oct-17 = 0, Nov-17 = 2, Dec-17 = 4, Jan-18 = 0, Feb-18 = 4, Mar-18 = 0, Apr-18 = 2, May-18 = 2, Jun-18 = 8, Jul-18 = 8, Aug-18 = 29, Sep-18 = 86, Oct-18 = 64, Nov-18 = 21, Dec-18 = 6, Jan-19 = 2, Feb-19 = 3, Mar-19 = 2

^ Confirmed AFM cases by CDC from August 2014 through January 2, 2020, with onset of condition by October 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.

Page last reviewed: January 3, 2020