PITTSBURGH (KDKA) — A mystery illness causing pain and weakness in the arms and legs, loss of bowel and bladder control, trouble swallowing, slurred speech — and no one knows what’s causing it.

One of the first cases appeared in Colorado and California in 2014. It has now been reported in 24 states and has affected 50 people this year, mostly children. There’s often a fever several days before the weakness begins.

“It may be a non-specific viral syndrome,” says Dr. George Small, a neurologist at Allegheny General Hospital.

Certain infections can cause this type of weakness: West Nile virus, Enterovirus, Polio, even a question of Zika. But these conditions don’t seem to explain it. So for now, it’s simply called Acute Flaccid Myelitis.

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Dr. Small is not aware of any cases locally. Suspicious cases turned out to be something else.

“I did see a case that could be described like this, and that patient turned out to have Lyme Disease,” he says.

Common findings on medical tests include bright segments in the spinal cord on MRI scan and inflammation in the spinal fluid. There’s no specific treatment. Most of the known cases have improved greatly, though for some, weakness remains.

The limited pattern of cases suggests that this condition peaks in the late summer and early fall, then fades away in the winter.

“I don’t think there’s any cause for alarm in the community,” says Dr. Small.

Best prevention right now is hand washing and avoiding sick people.

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