According to a new Canadian study, the mysterious ailments experienced by Canadian and US diplomats and their families while stationed in Cuba may have had nothing to do with so-called “sonic attacks,” identified in previous reports.

The study, obtained exclusively by Radio-Canada’s investigative TV program Enquête and reported Thursday by the CBC, suggests the cause could instead be neurotoxic agents used in pesticide fumigation — an entirely different avenue of investigation.

About 40 Canadians and Americans living in Havana fell victim to an unexplained illness starting in late 2016, complaining of concussion-like symptoms, including headaches, dizziness, nausea and difficulty concentrating. Some described hearing a buzzing or high-pitched sounds before falling sick.

It immediately sparked concerns over Cuban, or possibly even Russian surveillance methods — the rumour being that this was a possible side-effect of some new method of monitoring diplomats. The fact so many were affected, also raised alarm bells in diplomatic circles.

The incidents caused the administration of Donald Trump to charge that diplomats had been attacked by some sort of secret weapon. Canada has refrained from such charges.

The Canadian embassy in Havana. Credit: Zeenews

In the wake of these health problems, Global Affairs Canada commissioned a clinical study by a team of multidisciplinary researchers in Halifax, affiliated with the Brain Repair Centre, Dalhousie University and the Nova Scotia Health Authority, CBC reported.

“The working hypothesis actually came only after we had most of the results,” Dr. Alon Friedman, the study’s lead author, said in an interview.

The researchers identified a damaged region of the brain that is responsible for memory, concentration and sleep-and-wake cycle, among other things, and then looked at how this region could come to be injured, the CBC report said.

“There are very specific types of toxins that affect these kinds of nervous systems … and these are insecticides, pesticides, organophosphates — specific neurotoxins,” said Friedman. “So that’s why we generated the hypothesis that we then went to test in other ways.”

Twenty-six individuals participated in the study, including a control group of people who never lived in Havana.

The researchers — comprised of 15 principal investigators and their teams — conducted a thorough assessment of the Canadians’ symptoms, including blood tests and several brain imaging tests.

According to a CTV interview, the team actually used a simple Google search to determine that pesticides were used extensively in Cuba during a fumigation campaign against the Zika virus in 2016.

“We learned that (the diplomats’) houses and their areas were fumigated,” said Friedman.

Havana has been designated an “unaccompanied post” since April 2018, meaning Canadian families no longer accompany diplomats there, CTV reported.

According to the Ottawa Citizen, 15 people, including five diplomats and their families from the Ottawa area, are suing the federal government for CDN$28 million in connection with mysterious health issues they suffered when they were posted to Cuba.

The suit alleges the Canadian government failed to properly inform, protect, treat and support the Canadians.

“Throughout the crisis, Canada downplayed the seriousness of the situation, hoarded and concealed critical health and safety information, and gave false, misleading and incomplete information to diplomatic staff,” the suit alleges.

Meanwhile, the Trump administration on Thursday ordered the expulsion from the US of two members of Cuba’s delegation to the United Nations and restricted travel of the remaining mission members to Manhattan.

In an announcement just days before world leaders gather for the annual UN General Assembly, the US State Department accused the two Cuban diplomats of trying to “conduct influence operations” harmful to US national security but did not elaborate on the accusations or release their names.

It was the latest sign of deteriorating US relations with Cuba, since US President Donald Trump took office in January 2017, which has rolled back the detente initiated by his predecessor Barack Obama.