Havana syndrome (formally "anomalous health incidents"[6][7]) is a medical condition reported by U.S. and Canadian government officials and military personnel, primarily in overseas locations. Reported symptoms range in severity from pain and ringing in the ears to cognitive dysfunction[8][9] and were first reported in 2016 by U.S. and Canadian embassy staff in Havana, Cuba. Beginning in 2017, more people, including U.S. intelligence and military personnel and their families, reported having these symptoms in other places, such as China, India,[10] Europe, and Washington, D.C.[11] The most recent studies of over 1,000 reported cases of Havana syndrome have ruled out foreign involvement in all but a couple dozen cases.[2][12][13]