Three-year-old Carter Roberts was playful, healthy and active until he became one of over four dozen people in the United States diagnosed with acute flaccid myelitis, or AFM, NBC News reported.
He was unable to move his arms or legs, and "doctors were working really hard to try and figure out what was going on," said his mother, Robin Roberts.
The mysterious muscle weakness, similar to polio, appears to be on the rise this year.
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As of August 2016 there have been 50 cases of confirmed AFM across 24 states, the Centers for Disease Control and Prevention reported Monday, more than double 2015, when 21 cases for the whole year were reported.