AFM Cases & Outbreaks

What to know

As of February 6, 2025, there have been 0 confirmed cases out of 1 patient under investigation (PUI) in 2025 and 22 confirmed cases of out of 37 PUIs in 2024. There have been 769 confirmed cases since CDC began tracking AFM in August of 2014.

Annual AFM Cases by State

Annual maps represent only cases for whom information was sent to and confirmed by CDC as of February 6, 2025. Patients under investigation are still being classified, and the case counts are subject to change. Cases of AFM have occurred in 49 states and the District of Columbia.

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

AFM Confirmed Cases 2025

As of February 6, 2025, there have been 0 confirmed cases.

Annual AFM Cases 2024

As of February 6, 2025, there have been 22 confirmed cases in 14 states.

Cases by Month, 2014-2025

Most patients developed AFM between August and November, with increases in AFM cases in 2014, 2016, and 2018. Many viruses commonly circulate at this same time of year, including enteroviruses, which are likely responsible for the increase in cases in peak years.

Cases by Month Data Table

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Total
2014 -- -- -- -- -- -- -- 21 51 24 15 9 120
2015 2 2 1 0 1 0 2 3 1 4 2 4 22
2016 1 0 6 1 7 9 13 33 43 27 9 4 153
2017 2 5 5 4 2 4 3 1 4 0 3 5 38
2018 0 4 1 2 3 8 8 30 88 66 21 7 238
2019 2 4 4 3 5 2 5 4 6 7 2 3 47
2020 7 3 5 2 1 2 3 3 3 3 1 1 34
2021 3 2 3 1 3 3 2 2 2 1 4 3 29
2022 2 1 4 2 3 2 2 9 9 5 7 2 48
2023 2 2 2 0 1 3 3 1 1 2 0 1 18
2024 2 4 1 1 5 0 2 0 3 1 2 1 22
2025 0

Confirmed cases of AFM by month of illness onset. Case Counts are subject to change.

^ Confirmed AFM cases by CDC from August 2014 through February 6, 2025. 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 or flaccid 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.