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PHILADELPHIA (CBS) – The mysterious polio-like disorder that’s striking children around the country is growing, according to an update from federal health officials Tuesday.

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Many local cases have been treated at Children’s Hospital of Philadelphia. The CDC still has not pin-pointed exactly what’s causing this disorder, but they suspect a virus that circulates this time of the year.

The CDC is reporting 127 patients are under investigation for acute flaccid myelitis or AFM. Sixty-two cases of the rare but serious condition have now been confirmed in 22 states, including Pennsylvania and New Jersey.

“This is truly a mystery disease. We actually don’t know what is causing this increase. For some previous cases, we have identified one pathogen or another, but we have no unifying diagnosis,” said Dr. Nancy Messonnier of the National Center for Immunization and Respiratory Diseases.

AFM affects the nervous system, specifically part of the spinal cord often causing polio-like symptoms. Muscles and reflexes are weakened and some patients are left paralyzed.

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More than 90 percent of cases are in children.

Children’s Hospital of Philadelphia most recently had two cases in August.

“Any weakness, including trouble swallowing, weakness of an extremity, especially in a child who has recently gone through signs of an infection, those would be the main red flags,” said Sarah Hopkins. “Of course, I would suggest if your child develops weakness of any extremities, you have them assessed by a physician as soon as possible. We certainly don’t want to alarm people because it’s very rare, but at the same time, I believe it’s something that’s best to have checked out.”

AFM was first detected in 2014, when 120 cases were confirmed. In 2016, there were 149 cases.

The CDC says it seems to be following an every other year pattern that emerges in the fall.

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CDC officials say some possible suspected causes, like polio and West Nile virus, have been ruled out. Another kind of virus is suspected, but it’s been found in only some of the cases.