Umair Choudhry, 10, steps off a yellow school bus in Chicago wearing a helmet, mittens and a mouth guard. He's dressed for protection--not from the elements or schoolyard bullies but from himself. He has bitten his arms in the past and scarred his scalp by tearing out his hair. In his native Pakistan, his relatives think he is possessed by demons. "They said an evil spirit was making him hurt himself," says his mother Farah Choudhry. In the U.S., his affliction is known as autism.
Ricardo de Santiago-Carrillo, 34, who is confined at an immigration facility in El Centro, Calif., recalls...