The Centers for Disease Control and Prevention said in a Nov. 23 update that there are 116 confirmed cases of acute flaccid myelitis, a condition that affects the nervous system, causing a polio-like illness.

Although rare, the CDC said the 116 confirmed cases are among the 286 total reports the group received so far in 2018.

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“It affects the nervous system, specifically the area of the spinal cord called gray matter, which causes the muscles and reflexes in the body to become weak,” the agency said. “CDC has been thoroughly investigating the AFM cases that have occurred since 2014, when we first noted a large number of cases being reported.”

This 2014 electron microscope image made available by the Centers for Disease Control and Prevention shows numerous, spheroid-shaped Enterovirus-D68 (EV-D68) virions. Doctors have suspected a mysterious paralyzing illness, acute flaccid myelitis, might be tied to a kind of enterovirus, such as EV-D68 or EV-A71. A spike in EV-D68 illnesses coincided with the first mysterious wave of paralysis cases in 2014.

Credit: Cynthia S. Goldsmith, Yiting Zha

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Credit: Cynthia S. Goldsmith, Yiting Zha

The agency said it has not identified a confirmed cause for AFM. It said more than 90 percent of patients with AFM had a mild fever or respiratory illness consistent with a viral infection, such as enteroviruses, before they developed the condition.

The CDC is continuing to investigate why a small number of people develop AFM and most others recover.

Despite the illness being compared to polio, the CDC said it is not caused by poliovirus.

More information is at CDC.gov.