In October, a State Department official said the USA had "received a handful of reports from US citizens who report they experienced similar symptoms following stays in Cuba".
The State Department said an email notice Wednesday, May 23, 2018, that a USA government employee in southern China reported abnormal sensations of sound and pressure, recalling similar experiences among American diplomats in Cuba who later fell ill.
"We do not now know what caused the reported symptoms and we are not aware of any similar situations in China, either inside or outside of the diplomatic community".
The unusual incident recalls a similar spat of reports from Cuba, where USA officials reported symptoms consistent with a "sonic attack", or exposure to harmful frequencies, while overseas.
The United States past year made a decision to withdraw a large number of embassy staff from Cuba after diplomats stationed there complained of symptoms such as hearing loss, dizziness, tinnitus, visual difficulties, headaches and fatigue. The employee was sent back to the United States for assessment.
"We are working to figure out what took place both in Havana and now in China as well", Pompeo said.More news: Walmart reports $122.7bn Q1 revenue
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The person has been diagnosed with a mild traumatic brain injury (MTBI) blamed on a "sonic attack" with eerie similarities to an incident in Cuba.
The embassy's health alert says the government employee "recently reported subtle and vague, but abnormal, sensations of sound and pressure".
"The Department is taking this incident very seriously and is working to determine the cause and impact of the incident", Lee said in an email.
China's Foreign Ministry did not immediately respond to a request for comment. "Instead, move to a location where the sounds are not present", the recommendation said.
The spokeswoman added that the Chinese government is also investigating the matter.
At a congressional hearing in January, US officials detailed how personnel came to experience a variety of symptoms including sharp ear pain, headaches, ringing in one ear, vertigo, disorientation, attention issues and signs consistent with mild traumatic brain injury or concussion. Media reports have suggested that the Federal Bureau of Investigation has not been able to verify any evidence to support the sonic weapon theory.
Staff there reported symptoms including hearing loss, dizziness, fatigue and cognitive issues.