Since 2016, American and Canadian diplomats at an embassy in Havana, Cuba have suffered neurological problems thought to have been caused by mysterious "acoustic attacks" from some sort of sonic weapon. While several theories have been posited about the cause of the so-called Havana Syndrome, a new scientific study suggests that the sickness may be related to insecticides used in Cuba to combat mosquitos and stop the spread of the Zika virus. From CNN:
Testing on 26 Canadian diplomats in the period from August 2018 to February 2019 raised the possibility of "overexposure to cholinesterase inhibitors," possibly through insecticides. Cholinesterase is an enzyme required for the proper functioning of the nervous systems.
"While the source of exposure to toxins of the cholinesterase inhibitor family is not yet confirmed in our study, the use of insecticides readily and evidentially suggests itself," the study said. "Importantly, certain chemical classes of pesticides, such as organophosphates and carbamates, work against insects by inhibiting the action of cholinesterase, but can also be poisonous to humans….
The US Environmental Protection Agency canceled the use of Temephos in the United States in 2011, but the chemical is still used in Cuba and in some other countries.
The researchers wrote that, at the time, Cuba had well-documented efforts underway to stop the spread of the Zika virus, including mass indoor and outdoor fumigations. Embassy records also confirmed an increase in the number of times people sprayed for mosquitoes at the Canadian office and at staff homes in January 2017, which coincided with the time when people were reporting symptoms.