Canada is continuing to investigate the cause of the symptoms that were first reported by Canadians connected to the Havana embassy in 2017 and have also affected U.S. diplomats in Cuba.
The symptoms, which include dizziness, headaches and nausea, have been found in 10 of the 27 Canadian personnel and family members that initially received medical testing, the official said.
While there have been no new incidents since the fall of 2017, diplomatic families that have returned to Canada have continued to experience symptoms. In some cases, the symptoms have lessened in intensity before returning, the official said.
Canada has also recently received information from Canadian and American medical specialists that raised concerns of a possible type of acquired brain injury, the official said, while initial theories of a sonic attack first raised by U.S. officials last year or mass psychosomatic causes are now considered to be improbable.
Air and water quality tests of staff quarters in Havana did not indicate a cause for the health problems, the official told reporters.
The U.S. State Department said last August that Americans linked to its embassy in Cuba had experienced physical symptoms caused by unspecified "incidents" starting as far back as late 2016.
The United States said in March it was making permanent last year's decision to slash staffing at its Havana embassy by around two-thirds as the alleged health incidents among its diplomats remained unsolved.
Cuban officials have denied any involvement or any knowledge of what was behind the incidents. Canada has generally enjoyed good relations with Cuba, even as the United States mounted a decades-long economic blockade against the country.
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