OTTAWA (Reuters) - Ottawa will remove families of diplomats posted at its embassy in Cuba as the cause of unusual health symptoms is still unknown, though information from medical specialists has raised concerns of a new type of brain injury, Canada said on Monday.

Canada is still investigating 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, a senior government 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 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.

Due to the uncertainty, Canada’s embassy in Cuba will be designated as an unaccompanied post, meaning diplomats will not be stationed with their families, the government said in a separate statement.

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.

There are currently 15 staff in Havana, and Canada will review whether all the positions are needed, the official said.

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.

The symptoms appear to have affected only Canadian and American personnel, and there have been no signs travelers could be at risk, the official said.