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."