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CDC revises testing procedures for acute flaccid myelitis :

April 11, 2017

Federal health authorities are requesting new specimens as they investigate causes of acute flaccid myelitis (AFM).

The Centers for Disease Control and Prevention (CDC) now is asking for unspun cerebrospinal fluid (CSF) and whole blood in addition to other specimens from patients suspected of having AFM.

Researchers have been trying to determine whether 2014 outbreaks of AFM and enterovirus D68 (EV-D68) were linked, but have not been able to pinpoint a consistent cause of AFM cases.

“We decided to broaden our approach to testing so now (we’re) looking for both infectious and non-infectious etiologies, including immune-mediated mechanisms that might be responsible for the disease process,” said Janell Routh, M.D., M.H.S., a medical officer with the CDC.

AFM is defined as

  • acute onset of focal limb weakness and
  • MRI showing spinal cord lesion largely restricted to gray matter (confirmed case) or CSF with pleocytosis (probable case).

Patients also may present with facial droop, ptosis and difficulty swallowing or speaking. AFM is rare but serious. Physicians who suspect a patient may have AFM should contact their state or local health department and collect samples of CSF (spun and unspun), serum, whole blood, and stool or rectal swab for testing by the CDC.

Specimens should be collected as soon as possible, shipped within 24-48 hours of collection and sent overnight to arrive at the CDC on a Tuesday through Friday, according to the CDC. Additional details about specimen amounts, processing and storage are available at

“I think this emphasizes the importance of clinicians really identifying AFM as soon as possible, knowing the symptoms, knowing what to look for and making that determination,” Dr. Routh said. “The sooner we collect samples in proximity to the neurologic manifestations of AFM I think the sooner we may be able to get answers.”

The CDC no longer is asking for a respiratory nasopharyngeal or oropharyngeal swab. However, if another lab does test such a sample and finds enterovirus or rhinovirus, it can send it to the CDC for typing.

Enteroviruses, West Nile virus and adenoviruses all have been known to cause AFM. In 2014, an outbreak of EV-D68 occurred at the same time as an outbreak of 120 cases of AFM. After extensive testing, the CDC was not able to determine whether the virus was causing the outbreak. Last year, there were 136 confirmed cases of AFM in 37 states, but no consistent connection was found to EV-D68 or any other pathogen. There has been one case of AFM this year.

Based on data from the 2014 outbreak, treatment for AFM is largely supportive. The CDC is convening a panel of experts to potentially update the guidance later this year.

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