The U.S. Embassy in China issued a health alert on Wednesday after a U.S. government employee experienced an "abnormal" sound and suffered a mild brain injury - in an incident reminiscent of a mysterious illness that hit diplomats in Cuba.
A spokesperson at the U.S. Embassy in Beijing confirmed to CBS News that from late 2017 through April 2018, a U.S. government employee assigned to the Guangzhou Consulate reported "a variety of physical symptoms".
On Wednesday, a U.S. diplomat in China reported "abnormal" sensations of sound and pressure, which prompted the USA government to start looking into the incident.
The State Department said in its Wednesday statement that anyone who experienced "unusual acute auditory or sensory phenomena" while in China should move away from the source of the noise.
In an alert e-mailed to USA citizens in China, the embassy said that it does not know what caused the symptoms or of any similar situations in the country.
It added that U.S. Secretary of State Mike Pompeo told lawmakers that the "sonic attack" in China was "medically similar" to the incidents in Cuba. Both the State Department and Chinese government are investigating the case, reports CNN; the employee began reporting symptoms late previous year, and no other American personnel are known to have experienced anything similar.
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China's Foreign Ministry and National Health Commission did not immediately respond to faxed questions about the report.
In November 2016, United States diplomatic staff in Cuba said they began to experience symptoms and were subsequently treated for hearing loss, dizziness, balance problems and insomnia, all of which occurred after their exposure to alleged acoustic attacks.
The State Department was taking the incident very seriously and working to determine the cause and impact, the embassy said.
In the Cuba incident previous year, 21 people fell sick with injuries including hearing loss, cognitive issues and sleep difficulties in what the State Department called an "attack".
Staff there reported symptoms including hearing loss, dizziness, fatigue and cognitive issues, though Cuban officials dismissed the idea of acoustic strikes as "science fiction" and accused Washington of slander.
The cause of those incidents remains unresolved.