Havana Syndrome refers to a mysterious set of symptoms—headaches, dizziness, tinnitus, and cognitive issues—that has affected more than 1,500 U.S. intelligence and diplomatic personnel since 2016. The latest case, which was the most high-profile to date, is that of the former CIA Director James Woolsey, whose wife said that he was suffering from Havana Syndrome in the years leading up to his recent death. Let’s go through the details of what we know about this mysterious malady.