The cause of a mystery illness which plagued diplomatic staff in Cuba in 2016 may have been identified by Canadian researchers.
Some reports in the US suggested an "acoustic attack" caused US staff similar symptoms, sparking speculation about a secret sonic weapon.
But the Canadian team suggests that neurotoxins from mosquito fumigation are the more likely cause. The Zika virus, carried by mosquitoes, was a major health concern at the time.
So-called "Havana syndrome" caused symptoms including headaches, blurred vision, dizziness and tinnitus.
It made international headlines when the US announced more than a dozen staff from its Cuban embassy were being treated.
Cuba denied any suggestion of "attacks", and the reports led to increased tension between the two nations.
The Canadian team from the Brain Repair Centre in Halifax thinks it now has the answer.
Canadian diplomats were affected by similar reactions to US counterparts - though the study noted that the symptoms of the Canadians were more gradual than in some of the US cases.
The study notes that tests carried out on 28 participants - seven of whom were tested both before and after being posted to Havana - support a diagnosis of brain injury acquired by diplomats and their families while in Cuba.
The patterns of brain injury "all raise the hypothesis of recurrent, low-dose exposure to neurotoxins", the report said.
But the low, consistent doses the researchers believe were delivered are consistent with exposure to commercial pesticides, the study's authors said.
And fumigation in Cuba increased after the country "declared war" on the Zika virus, spraying gas around or even inside diplomats' homes.