"We have not been able to identify a cause for the majority of these cases", said Dr. Nancy Messonnier, director of the CDC's National Center for Immunization and Respiratory Diseases.
The CDC announced Wednesday that Acute Flaccid Myelitis has spread to 22 states, with more than 62 confirmed cases nationwide.
The CDC says there are preventative measures people can take to reduce the risk of infections that could lead to AFM.
There were 120 cases in 2014 when the disease was first detected in the United States.
So far the disease has claimed one life in the U.S.
Acute flacid myelitis or AFM is not new, but cases have been on the rise since 2014.More news: Banksy video suggests he planned to shred entire Girl With Balloon artwork
"We are actually looking at everything. We are looking beyond the normal infectious diseases that can cause this".
This year's numbers are similar to 2016 and 2014.
Lacking an established cause, health officials confirm cases through a review of brain scans and symptoms. However, the illness has been on the rise in the USA since 2014.
The agency also said it will post case count updates on its website every week now, a change from the monthly updates it had been giving.
Depending on which part of the spine is damaged, different muscles can become weak or paralyzed. The once-healthy child now relies on a wheelchair to get around, a ventilator to breathe and a feeding tube to eat. AFM may be one of them. Minnesota has seen seven cases in children this year alone. Ninety per cent of children diagnosed with AFM are under 18, with the average age of children in confirmed cases being about 4.
According to the National Institutes of Health, AFM is classified as a rare disease. There was one confirmed death previous year, the CDC said on Tuesday. It is important that tests are done as soon as possible after someone develops symptoms. "Parents need to know that AFM is very rare even with the increase in cases we're seeing right now". It's also a serious condition. It's unclear from mouse studies whether AFM symptoms will return in afflicted individuals, Tyler says.More news: Liverpool, Manchester City are laughing at Manchester United, says Paul Scholes
Messonnier did not address enterovirus D68 directly during the news conference and said the CDC has not yet had time to fully analyze the cases from this summer and fall.
Doctors and experts are all emphasizing the importance of reporting potential symptoms, like extreme limb weakness or paralysis, early.
Some children with AFM recover completely, but others are disabled for years.
It is "a pretty dramatic disease", but fortunately most kids recover, Messonnier said. Once a virus has attacked the nervous system, there's no known medical intervention that can reverse the effects. Rehabilitation therapy can help patients regain function.
People can protect themselves from contracting AFM using methods similar to preventing getting the flu, Ellerin said. Some treatments such as high doses of steroids are used, but it is not certain they work.
Officials have not determined a cause of the rare disease.More news: Missing journalist: Alleged member of Khashoggi 'hit squad' seen at Saudi consulate