Multistate (USA) - Update: Acute flaccid myelitis, more cases reported

October 10, 2018
CDC (US); State Health Agencies

According to the Centers for DIsease Control and Prevention (CDC), so far in 2018, there are 38 confirmed cases of acute flaccid myelitis (AFM) ocurring in 16 states across the U.S.

Since August 2014, CDC has seen an increased number of people across the United States with AFM. CDC has not confirmed the cause for the majority of these cases. CDC has been actively investigating these AFM cases, and it continues to receive information about suspected AFM cases.

The graph below by CDC shows the number of AFM cases confirmed by CDC as of September 30, 2018, with onset of the condition through September 30, 2018.

^ Confirmed AFM cases that CDC has been made aware of as of September 30, 2018 with onset of the condition through September 30, 2018. The 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.

The following are the latest updates from several states reporting AFM cases.


The Colorado Department of Public Health and Environment continues to work with CDC to investigate an outbreak of viral infections with neurologic complications among young children. Testing by the CDC shows most of these cases are associated with enterovirus A71.

This year, Colorado has had 41 cases of enterovirus A71 infections associated with neurologic illness in children. As part of this outbreak, Colorado also has had 14 cases of AFM. Of the AFM cases, 11 tested positive for enterovirus A71, one tested positive for enterovirus D68, and two tested negative for enteroviruses.

While all the patients were hospitalized, nearly all have fully recovered. There have been no deaths.

Acute flaccid myelitis is a condition that affects the spinal cord; most patients who get it have a sudden onset of limb weakness, and most recover from the illness.

Enteroviruses are common and can cause cold-like illnesses; hand, foot and mouth disease; and skin rashes. EV-A71 and EV-D68 are less-common types of enterovirus in the United States, and usually cause mild illness. Rarely, they may cause neurologic illnesses not commonly seen with other enteroviruses, such as meningitis, encephalitis and acute flaccid myelitis.

All enteroviruses are spread through contact with an infected person’s feces; eye, nose and mouth secretions (such as saliva, nasal mucus or sputum); and fluid from blisters caused by the virus. Some people with enteroviruses have no symptoms but still can spread the virus to others. Typically, enterovirus cases increase in the summer and fall.

There is no vaccination or specific treatment for enteroviruses. People with mild illness typically need treatment only for symptoms. However, some illnesses caused by EV-A71 and EV-D68 can be severe enough to require hospitalization.

The state health department has been monitoring this situation closely since early spring. In addition to investigating the outbreak, the department has issued alerts to health care providers on how to test for the viruses and enhanced guidance to child care centers on infection prevention.

Parents and guardians should contact a health care provider if they or their children have:

  • Severe symptoms such as sudden weakness in arms and legs, trouble breathing, unsteady walking, severe headache, stiff neck or seizures.
  • Dizziness, wobbliness, or abnormal, jerking movements that are worse at night.
  • Fever along with any other concerning symptoms.

Colorado has experienced previous outbreaks of less-common enteroviruses. In 2014, enterovirus D68 caused an outbreak of respiratory illness in Colorado children and was associated with 11 cases of AFM. In 2003 and 2005, enterovirus A71 caused outbreaks similar to what Colorado is experiencing now, with eight cases of central nervous system infections occurring in each of those years.


The Illinois Department of Public Health (IDPH) has received recent reports from health care providers of nine sporadic, clinically diagnosed cases of AFM. IDPH is working with the health care providers to collect necessary information to send to CDC. The CDC reviews medical information on all reported clinical cases to classify cases as AFM. The case reports are from individuals younger than 18 years of age and from northern Illinois. Specific location information is not available. The CDC will make the final determination on AFM classifications and numbers are subject to change.

In September, IDPH issued an alert to health care providers about AFM, including information about reporting this clinical syndrome and submitting specimens. Illinois has monitored this syndrome since 2014 when it was first described by CDC. Since 2015, four cases reviewed by CDC experts have been counted in Illinois. IDPH continues to work closely with the CDC to monitor reports of AFM.


The Washington State Department of Health and four local public health agencies are investigating reports of five children hospitalized for sudden onset of paralysis of one or more limbs. The Department of Health is working with experts in neurology from CDC for confirmation of acute flaccid myelitis (AFM).

All cases are among infants and children under age six who all reportedly had symptoms of a respiratory illness in the week prior to developing symptoms of AFM. Four of the five had fever of 100.4 F or greater. The children are residents of King County (2), Pierce County (1), Lewis County (1), and Snohomish County (1).

The children are being evaluated for AFM, a rare condition that affects the nervous system, specifically the spinal cord. Symptoms typically include sudden weakness in one or more arms or legs, along with loss of muscle tone and decreased or absent reflexes. AFM can cause a range of types and severity of symptoms, but the commonality among them is a loss of strength or movement in one or more arms or legs. The cause of any individual case of AFM can be hard to determine, and often, no cause is found. CDC specialists will make the final determination if these cases are AFM.

“At this point there isn’t evidence that would point to a single source of illness among these cases,” said Dr. Scott Lindquist, state infectious disease epidemiologist at the Department of Health. “We’re working closely with medical providers and public health agencies. We’ll continue to investigate and share information when we have it.” 

Some viruses and germs have been linked to AFM, including common germs that can cause colds and sore throats, and respiratory infections. It can also be caused by poliovirus and non-polio enteroviruses, mosquito-borne viruses (such as West Nile virus or Zika virus) and possibly by non-infectious conditions.

While there are no specific recommendations for avoiding AFM, you can help protect yourself from some of its known causes by: washing your hands often with soap and water, avoiding close contact with sick people, and cleaning surfaces with a disinfectant, especially those that a sick person has touched. Staying updated on recommended immunizations is also important to avoid vaccine preventable illnesses.

The Department of Health sent a notice to public health departments for distribution to healthcare providers across the state to be alert for other suspected AFM cases.

In 2016 there was a cluster of nine cases of AFM in Washington state. In 2017 there were three cases, and since the beginning of 2018 there has been one case in the state. For more information on AFM, visit the CDC website. From January 1st to September 30th, a total of 38 people in 16 states have been confirmed to have AFM. Most of these illnesses have been in children.

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