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CDC urges vigilance for acute flaccid myelitis :

July 9, 2019

Public health officials are asking doctors to be on the lookout for acute flaccid myelitis (AFM) and report it quickly as the season for outbreaks approaches.

The syndrome is rare but serious, characterized by sudden limb weakness and typically preceded by respiratory illness or fever. So far this year, there have been 11 cases in eight states, and officials say learning more about AFM is a priority.

“We know families are facing uncertainties when it comes to their child’s recovery from AFM, and we want parents to know we are keeping their children front and center and working with our partners to better understand this illness, its risk factors, and ways to treat and prevent it,” saidAnne Schuchat, M.D., Centers for Disease Control and Prevention (CDC) principal deputy director.

Since 2014, there have been 570 cases in 48 states, typically occurring in late summer or early fall. The largest outbreaks have occurred every other year, but CDC experts are still trying to pinpoint the cause of the outbreaks and say there are no guarantees that AFM will stick to the same pattern.

In a new Vital Signs report, the CDC analyzed cases from 2018, which saw the largest outbreak including 233 confirmed cases in 41 states with a median age of 5 years. Just under half of the respiratory and stool samples were positive for enteroviruses or rhinoviruses.

“We really do suspect viruses play a role, and enterovirus is among the leading suspects,” said pediatricianTom Clark, M.D., M.P.H., deputy director in the CDC Division of Viral Diseases.

Physicians who suspect a patient has AFM should perform a workup, including MRI and collection of respiratory, stool, serum and spinal fluid samplesfor testing. They also should report suspected cases to their state or local health department.

Some of the specimen samples may have been negative in 2018 due to delays in collecting them. The time from onset of limb weakness to specimen collection among last year’s cases was two to seven days, while reporting to the CDC took 18-36 days.

The CDC urged physicians to do both more rapidly.

“When specimens are collected as soon as possible after symptom onset, we have a better chance of understanding the causes of AFM, these recurrent outbreaks and developing a diagnostic test,” Dr. Schuchat said. “Rapid reporting also helps us to identify and respond to outbreaks early and alert other clinicians and the public.”

The Council of State and Territorial Epidemiologists recently updated its case definition to say the MRI should include evidence of spinal lesions with at least some gray matter involvement. However, the CDC noted a physician’s definition for diagnosis may not be the same as the one used by public health officials, and physicians should not delay their diagnosis and management while waiting for a CDC classification.

While there is no specific treatment for AFM, Dr. Clark said “early and aggressive physical therapy and rehabilitation holds good promise,” which also supports the need for early recognition.

Clinicians can get help with diagnosis and management of AFM through a new 24-hour consultation service with experts from the University of Texas Southwestern and Johns Hopkins University that was created by the Acute Flaccid Myelitis Workgroup and the Transverse Myelitis Association. To consult with a specialist, visit

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