The first cases emerged in late November, last year, in Qom, some 125 kilometers (80 miles) southwest of Iran’s capital, Tehran. There, in a heartland of Shiite theologians and pilgrims, students at the Noor Yazdanshahr Conservatory fell ill in November. They then fell ill again in December. Other cases followed, with children complaining about headaches, heart palpitations, feeling lethargic or otherwise unable to move. Some described smelling tangerines, chlorine or cleaning agents.