Confirmation of the symptoms in a 25th embassy employee - who was one of two staffers medically evacuated from Havana - brings investigators no closer to determining exactly what happened since the first incident was reported in late 2016.
"We still don't know, to this day, what is causing it and who is responsible," said State Department spokeswoman Heather Nauert.
The second employee evacuated from Cuba is still being evaluated, Nauert said. Before this incident, the last time an embassy worker was known to have been affected was in August of 2017.
The stricken embassy employees both in Cuba and China have reported health issues, including concussions, hearing loss and disorientation, after hearing odd, unexplained sounds. Many have been screened and treated by specialists in brain injury at the University of Pennsylvania.
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