The U.S. State Department issued a warning to U.S. citizens in China Wednesday after a government employee experiencing “abnormal” sounds and pressure received a mild traumatic brain injury.
“A U.S. government employee in China recently reported subtle and vague, but abnormal, sensations of sound and pressure,” the department said. “The U.S. government is taking these reports seriously and has informed its official staff in China of this event.”
A health alert released by the U.S. consulate in Guangzhou, the Chinese city where the employee was stationed, tells Americans to report any similar medical issues “that developed during or after a stay in China.”
The consulate describes potential symptoms to include “acute auditory or sensory phenomena accompanied by unusual sounds or piercing noise” and warns U.S. citizens against attempting to locate its source.
“We do not currently 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 department added.
Speaking with The Washington Posts, Jinnie Lee, a spokeswoman for the U.S. Embassy in Beijing, said China has also begun looking into the incident.
“The Chinese government has assured us they are also investigating and taking appropriate measures,” Lee said.
While the cause of the injury is reportedly unknown, the symptoms are being compared to those experienced by U.S. government employees in Cuba.
U.S. Secretary of State Mike Pompeo drew comparisons to Cuba Wednesday while testifying in front of Congress.
“The medical indications are very similar, and entirely consistent with, the medical indications that were taking place to Americans working in Cuba,” Pompeo said.
At least 24 diplomats in Havana suffered issues including brain trauma and hearing loss shortly after the election of U.S. President Donald Trump in November, resulting in large staff reductions months later.
Cuba denied involvement and accused the U.S. of “political manipulation” after investigators said the injuries may have resulted from a sonic weapon attack.