Canadian researchers say they may have identified the cause of a mystery illness which plagued diplomatic staff in Cuba in 2016.
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.