Want to learn more? 

www.cdc.gov/vitalsigns/afm

JUL. 2019

#vitalsigns

PROBLEM:

Acute Flaccid Myelitis (AFM)

Promptly recognize & rapidly report

Overview:

Acute flaccid myelitis (AFM) is a rare but serious 

syndrome (a pattern of symptoms) that causes 

limb weakness, mostly in children. Three national 

outbreaks have occurred starting in 2014, when 

CDC began surveillance for AFM. 

• Most patients developed AFM in late 

summer or early fall. 

• Most patients had respiratory symptoms or 

fever consistent with a viral infection less 

than a week before onset of limb weakness. 

• CDC believes viruses, including 

enteroviruses, play a role in AFM. 

• Currently, there are no proven ways to treat 

or prevent AFM. 

• Prompt symptom recognition, specimen 

collection, and reporting to CDC are all 

critical to improve understanding of this 

complex syndrome, including its risk factors, 

outcomes, possible treatments, and ways to 

prevent it.

5 The average age of 

patients with AFM 233 was 5 years. 

233 AFM cases 

occurred in 41 

states in 2018. 18

On average, CDC 

received reports of 

suspected AFM cases 

18 days after patient’s 

limb weakness began.

Recognizing AFM is challenging.

• AFM is rare, and there is no lab test 

available yet to diagnose patients.

• When clinicians recognize AFM early, they 

can quickly: 

 Get patients the best care, including 

treatment and rehabilitation. 

 Collect lab specimens like blood or 

urine to better understand AFM and 

its causes.

 Report suspected cases for prompt 

investigation and outbreak detection.
For more information

1-800-CDC-INFO (232-4636)

TTY: 1-888-232-6348 | Web: www.cdc.gov

Centers for Disease Control and Prevention

1600 Clifton Road NE, Atlanta, GA 30329

Publication date: July 9, 2019

CS304508-A

Clinicians should: 

• Strongly suspect AFM in patients with acute flaccid limb weakness, 

especially after respiratory illness or fever, and between August 

and October.

• Hospitalize patients immediately, collect lab specimens, diagnose, 

and begin medical management. 

 Don’t wait for CDC’s case classification for diagnosis.

• Alert the health department and send lab specimens and 

medical records.

Most AFM cases occur in late summer & early fall

Putting Together the Pieces of AFM 

SOURCE: CDC Vital Signs, July 2019

THE WAY FORWARD

CDC IS:

• Monitoring AFM trends and the 

clinical presentation. 

• Researching possible risk factors. 

• Conducting advanced lab testing 

and research to understand how viral 

infections may lead to AFM. 

• Tracking long-term patient outcomes. 

CLINICIANS CAN:

• Contact neurologists specializing 

in AFM through the AFM Physician 

Consult and Support Portal for 

help with patient diagnosis

and medical management.

https://bit.ly/2Y2U3VR

• Contact CDC with any questions 

about AFM, including how to 

report cases and collect 

appropriate specimens.

HEALTH DEPARTMENTS CAN:

• Work with CDC to collect medical 

information, MRI images, and 

specimens, and classify cases.

• Communicate information about 

AFM to clinicians and the public.

PARENTS CAN:

• Immediately seek medical care if 

their child develops sudden arm or 

leg weakness. 

Clinicians: Timing is Key for AFM

Collect specimens

& then get MRI

Collect 

cerebrospinal fluid 

(CSF), serum, stool, 

and nasopharyngeal 

(NP) swab as soon 

as possible, and 

handle and store 

specimens properly 

Rapidly report 

to health 

department

If the MRI shows a 

spinal lesion with 

some gray matter 

involvement, alert 

the health 

department and 

send specimens 

and medical records

Diagnosis 

& medical

management

Refer to specialists, 

monitor for signs 

of worsening 

symptoms, 

hospitalize if 

indicated, and 

begin treatment 

and rehabilitation

Recognize 

AFM early

Be alert for onset 

of acute flaccid 

limb weakness and 

consider AFM on 

your differential 

diagnosis

WHO

WHAT

WHEN

WHERE

WHO

570 AFM cases, mostly children, 

since 2014

WHEN

AFM outbreaks have occurred 

every two years starting in 2014, 

in late summer and early fall

48 states and D.C. have had 

AFM cases since 2014

WHERE

CDC believes viruses, including 

enteroviruses, play a role in AFM 

WHAT

WHAT