A US State Department employee has suffered "subtle and vague, but abnormal, sensations of sound and pressure" that later lead to a diagnosis of "mild traumatic brain injury" while working in China - resulting in a warning to all US citizens there.
"The Chinese government has assured us they are also investigating and taking appropriate measures", said Lee, the embassy spokeswoman.
"We can not at this time connect it with what happened in Havana, but we are investigating all possibilities", a USA embassy official told Reuters.
That study found that 21 US government employees in Havana experienced "persistent cognitive, vestibular, and oculomotor dysfunction, as well as sleep impairment and headaches, were observed. associated with reports of directional audible and/or sensory phenomena of unclear origin".
"The embassy learned that the clinical findings of this evaluation matched mild traumatic brain injury", Lee said.
"A US government employee in China recently reported subtle and vague, but abnormal, sensations of sound and pressure", the U.S.
"The U.S. government is taking these reports seriously and has informed its official staff in China of this event", the embassy said in a statement.
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The State Department and Chinese government are investigating all possibilities behind the brain injury.
China's Foreign Ministry did not immediately respond to a request for comment.
The department also warned against attempting to locate the source of any unusual sounds.
More than 20 members of staff in Havana were harmed in the "health attacks", according to the state department.
Suspected "sonic attacks" affecting more than a dozen US diplomats and family members in Havana beginning in November 2016 led to the U.S.
Multiple workers in Havana complained of an incapacitating "high pitch beam of sound".
Despite hundreds of billions of dollars in annual trade between them, China and the US are considered strategic rivals for influence in Asia. "Instead, move to a location where the sounds are not present", the emailed alert said.
Of the 21 medically confirmed U.S. victims, some have permanent hearing loss or concussions, while others suffered nausea, headaches and ear-ringing.