The mystery illness first reported in late 2016 among U.S. diplomats in Havana is now affecting personnel at a U.S. consulate in Guangzhou, China. Yet 18 months in, an explanation is nowhere in sight, although hypotheses have proliferated. Former Secretary of State Rex Tillerson blamed a deliberate "health attack" for the Cuba ailments, whereas some neuroscientists and psychologists—and a panel of Cuban scientists—have written them off as the result of stress. Some unaffected diplomats from the Havana embassy agree. But a few researchers are finding hints of a physical cause for the symptoms, which include headaches, dizziness, and insomnia. In the latest proposal, Michael Hoffer, an otolaryngologist at the University of Miami in Florida, and his colleagues describe a unique vestibular and cognitive disorder in two dozen people evacuated from the Havana embassy.