OTTAWA—Months after Canadians diplomats and family members based in Cuba reported strange health problems, the federal government says it’s no closer to solving the mystery of what made them sick.

Noises in the garden, pressure waves, headaches, dizziness, sleeplessness and a child’s nosebleed are among the clues and symptoms that are now the focus of a government-wide investigation led by the Royal Canadian Mounted Police but also involving the Department of National Defence, Health Canada and other federal agencies.

A Global Affairs official briefed reporters Wednesday on what the federal government knows so far about the curious crisis that has also hit American diplomats based in Havana and left Washington scrambling to find answers too.

Despite the health concerns — the most recent possible incident was reported in December — operations continue as normal at the Canadian embassy, though unspecified security precautions have been taken.

And the foreign affairs department doesn’t think it needs to follow Washington’s lead and warn tourists against visiting the Caribbean isle, saying there’s no evidence yet that Canadian visitors have been affected by the mystery ailments.

Yet the department also admits it is in uncharted waters, confronting a situation it’s never seen elsewhere.

The drama started in April, when American diplomats in Cuba asked their Canadian counterparts whether they had experienced any unexplained health ailments or heard any strange sounds.

The Americans had been suffering symptoms such as nausea, headaches, nosebleeds or ear complaints since the previous December, said the official, who spoke on the condition of anonymity.

After polling embassy staff, some Canadians and their dependants reported that they too had experiencing these kinds of symptoms. In all, 27 people from 10 families underwent testing and of those, eight individuals required medical followup.

A panel of Senate lawmakers questioned key U.S. State Department personnel Tuesday, trying to get to the bottom of why U.S. embassy personnel in Cuba have reported medical problems that some are attributing to "sonic attacks" in Havana. (The Associated Press)

None of the eight suffered permanent damage and all have returned to work or school, the official said.

The incidents appear to have been clustered in early spring, though an individual in August and another in December complained about feeling waves of pressure.

The U.S. announced in September that it was withdrawing family members of diplomats and nonessential personnel from its embassy in Cuba.

And it issued a travel warning to visitors, saying that the U.S. embassy staff “appear to have been targeted in specific attacks” that left them injured.

“Because our personnel’s safety is at risk, and we are unable to identify the source of the attacks, we believe U.S. citizens may also be at risk,” the advisory said, adding that attacks occurred in U.S. diplomatic residences and two Havana hotels.

U.S. personnel first reported symptoms about a year ago, “many of which are not easily quantifiable and not easily attributable to a specific cause,” Dr. Charles Rosenfarb, medical director at the U.S. State Department, told a Senate Foreign Relations subcommittee hearing on Tuesday.

Twenty-four U.S. personnel have been affected. The type of injuries was “most likely related to trauma from a non-natural source,” Rosenfarb said, according to a transcript of his remarks.

They described experiencing sensations such as “high-pitched beam of sound,” an “incapacitating sound” or an intense pressure in one ear, he told U.S. lawmakers.

Those descriptions prompted speculation that it was a so-called sonic or acoustic attack, an explanation discounted by some.

But the Canadian experience has been different, the official said Wednesday. Some Canadians have reported hearing a noise — similar to warping sheet metal — but only one of those then reported health symptoms.

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That’s why the Canadian investigation continues to consider all possible causes, ranging from foul play to factors such as air and water, with environmental assessments underway, the official said Wednesday.

Strangely, only Americans and Canadians appeared to have been affected. Cubans and diplomats from other countries have not reported ailments. Whatever the cause, it seems to originate at residences and two hotels, rather than the embassies.

Washington expelled 15 Cuban diplomats in retaliation, charging that Cuba had failed to protect foreign diplomats.

But the Canadian official said that the Cubans appear as puzzled as everyone else about the case. With more than 1.2 million Canadian visitors to the island every year, he said that Cuba has a vested interest in solving the mystery.