Summary of Findings: Investigation of Acute Flaccid Myelitis in U.S. Children, 2014-15

From August to October 2014, CDC received increased reports of children across the United States who developed a sudden onset of weakness in one or more arms or legs with MRI scans that showed inflammation of the gray matter—nerve cells—in the spinal cord. This illness is called acute flaccid myelitis. CDC continues to receive sporadic reports of cases.

From August 2014 to July 2015, CDC has verified reports of 120 children in 34 states who developed acute flaccid myelitis that meets CDC's outbreak case definition.

The median age of the children was about 7 years.
Almost all of them were hospitalized; some were put on breathing machines.
Most patients had fever and/or respiratory illness before onset of neurologic symptoms.
About 7 out of 10 of the children had elevated white blood cell counts, often with elevated protein levels, in their spinal fluid.
About two thirds of the children who have been observed (median 19 days) after their illness reported some improvement in symptoms, while about one third showed no improvement. Only two of the children have fully recovered.
CDC tested many different specimens from these patients for a wide range of pathogens that can result in this syndrome. Despite extensive testing, no pathogen was consistently detected in the patients’ spinal fluid; a pathogen detected in the patients’ spinal fluid would be good evidence to indicate cause of the illness.

A brief summary of the status of the investigation through November 13, 2014 is available in CDC’s MMWR: Acute Flaccid Myelitis Among Persons Aged ≤21 Years — United States, August 1–November 13, 2014.

The specific causes of this illness are still under investigation. However, these cases are most similar to illnesses caused by viruses, including

enteroviruses (polio and non-polio),
adenovirus,
West Nile virus and similar viruses, and
herpesviruses.

The apparent increase in cases of acute flaccid myelitis in 2014 coincided with a national outbreak of severe respiratory illness among children caused by enterovirus D68 (EV-D68). However, despite this close association in timing, a cause for the 2014 acute flaccid myelitis cases has not been determined.

Neurologic Illness with Limb Weakness

Every year, children in the United States develop neurologic illness with limb weakness, and often the causes are not identified. Such illnesses can result from a variety of causes, including viral infections, environmental toxins, genetic disorders, and Guillain-Barre syndrome, a neurologic disorder caused by an abnormal immune response that attacks the body’s nerves.

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What CDC is Doing

CDC is

re-emphasizing the importance of continued vigilance by healthcare professionals for cases of acute flaccid myelitis among all age groups
verifying reports of cases of acute flaccid myelitis using the CSTE case definition
working with healthcare professionals and state and local health departments to investigate and better understand the cases of acute flaccid myelitis, including potential causes and how often the illness occurs
testing specimens, including stool, respiratory and cerebrospinal fluid, from the children with acute flaccid myelitis
providing information to healthcare professionals, policymakers, general public, and partners in various formats, such as the Morbidity and Mortality Weekly Report, health alerts, websites, social media, and presentations
pursuing a multi-pronged approach to further explore the potential association of acute flaccid myelitis (AFM) with enterovirus D68 (EV-D68) and other etiologies as well as risk factors for AFM. This includes
- testing specimens from AFM cases for a wide range of viruses that may be associated with this clinical presentation and testing to possibly detect previously unrecognized pathogens and
- collaborating with several medical institutions to review MRI scans of children from the past 10 years to determine the baseline prevalence of AFM and identify characteristics of patients presenting with AFM.

Information for Parents

If your child appears to have a sudden onset of weakness in arms or legs, parents should contact a healthcare provider to have their child assessed for possible neurologic illness.

Being up to date on all recommended vaccinations is the best way to protect yourself and your family from a number of diseases that can cause severe illness and death, including polio, measles, whooping cough, and acute respiratory illnesses such as influenza.

You can help protect yourselves from infections in general by

washing your hands often with soap and water,
avoiding close contact with sick people, and
disinfecting frequently touched surfaces.

You can protect yourself from mosquito-borne viruses, such as West Nile virus, by using mosquito repellent, and staying indoors at dusk and dawn, which is the prime period that mosquitoes bite.