(Radio Iowa) — A rare disease that causes muscle weakness, loss of reflexes and even paralysis has appeared in Iowa — twice — in recent weeks and the experts are puzzled. State health officials confirm two cases of a rare polio-like illness which attacks the nervous system called acute flaccid myelitis, or AFM. The first case is a three-year-old boy in Grimes, while the second is in a person under 18 in western Iowa. Minnesota reports seven cases of AFM since mid-September, while 62 are reported nationwide in 22 states.

There is no known cure and federal investigators haven’t been able to identify a common cause in the cases which usually start as a cold.