The mysterious polio-like disorder that's striking children around the country is growing, according to an update from federal health officials Tuesday.
A rare illness doctors are comparing to polio is spreading in states surrounding North Dakota.
CNN found 47 confirmed cases and 49 more that were suspected or being investigated, for a total of 96 cases in 30 states in 2018.
"There is a lot we don't know about AFM and I am frustrated that despite all of our efforts, we haven't been able to identify the cause of this mystery illness", Nancy Messonnier, a top official at the Centers for Disease Control, said Tuesday. Another spike came in 2016.
Some possible causes being investigated by the CDC include enteroviruses, which affect the digestive system, and rhinoviruses - the infectious agents associated with the common cold.
Dr. Messonnier said, "We want to encourage parents to seek medical care right away if you or your child develops symptoms of AFM, such as sudden weakness and loss of muscle tone in your arms or legs". However, none of the US patients tested positive for polio, and, according to Dr. Messonnier, none of this year's cases have been linked to West Nile virus. Specifically, the disease affects the area of the spinal cord called gray matter. The other good news is that only one of the 386 cases so far has resulted in death.
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The medical name is Acute Flaccid Myelitis, or AFM.
After testing patients' stool specimens, the CDC determined poliovirus is not the cause of the AFM cases.
Cases have been on the rise since 2014.
It is "a pretty dramatic disease", but fortunately most kids recover, Messonnier said.
People can protect themselves from contracting AFM using methods similar to preventing getting the flu, Ellerin said.
The CDC says it seems to be following an every other year pattern that emerges in the fall. To date, no pathogen has been consistently detected in AFM patients.
And while the causes of acute flaccid myelitis are not known, it is important to practice disease prevention steps, such as staying up-to-date on vaccines and washing your hands. Six children in Minnesota were diagnosed with the disease since mid-September.