A woman walks past the United States embassy in Beijing on February 6, 2010 where a US missionary released by North Korea after entering the communist country on Christmas Day to protest against human rights abuses is being assisted by embassy consular officers after his arrival in Beijing en route to his homeland, the US embassy said.  North Korean authorities detained Robert Park, 28, for illegal entry after he crossed a frozen border river from China carrying a letter calling on leader Kim Jong-Il to free political prisoners, shut prison camps, improve rights and step down. The missionary had expressed "sincere repentance" for his actions, which were prompted by "false propaganda" from the West, the North's official news agency said on February 5 upon announcing his release.    AFP PHOTO/Frederic J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
US issues health warning to Americans in China
01:40 - Source: CNN
Washington CNN  — 

A number of US personnel in China have been sent back to the United States for further health screenings after concerns over reports of mysterious acoustic incidents similar to the Cuba “sonic attacks.”

The US State Department said Wednesday a medical team had been sent to Guangzhou, in southern China, to conduct screenings of all US government employees and family members who asked for them.

“As a result of the screening process so far, the Department has sent a number of individuals for further evaluation and a comprehensive assessment of their symptoms and findings in the United States,” State Department spokeswoman Heather Nauert said.

The screenings came after a US government employee in Guangzhou fell ill in early 2018 after reporting “abnormal sensations of sound and pressure” which resulted in a mild brain injury.

The US consulate in Guangzhou issued its second health notice around the issue Thursday, saying a single government employee had reported “subtle and vague, but abnormal, sensations of sound and pressure.” The consulate said it did not know what had caused the symptoms, but was taking the incident “seriously.”

Chinese Foreign Ministry spokeswoman Hua Chunying said Thursday the US government hadn’t told China about the new cases. She said the US could reach out directly to Chinese authorities and they would investigate.

Speaking in Washington in May, Chinese Foreign Minister Wang Yi said China had been investigating the incident but hadn’t yet found the source of the “sonic influence.” Wang added he didn’t want to see individual cases “magnified, complicated or politicized.”

Just days earlier, Secretary of State Mike Pompeo announced Tuesday the formation of a task force in response to “unexplained health incidents” affecting US diplomats and their family members.

Pompeo had previously said on May 23 the Guangzhou incident was very similar to the mysterious sound-related illnesses experienced by US personnel in Cuba in 2016 and 2017, a statement which was reiterated by his department on Wednesday.

Some officials have characterized these illnesses as “sonic attacks” or “acoustic attacks” as they often coincided with a high-pitched sound.

US officials have detailed how personnel came in Cuba 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.

In nearly all cases there – 24 in total – the ailments were preceded by some sort of “acoustic element,” such as a “high-pitched beam of sound” or a “baffling sensation akin to driving with the windows partially open in a car.”

A study earlier this year outlined the extensiveness of the problem, but the State Department has not pointed to a specific cause behind the mysterious incidents.

CNN’s Michelle Kosinski, Steven Jiang, Maegan Vazquez, Laura Koran and Patrick Oppmann contributed to this report.