On Wednesday, a spokesman for the US State Department reported that they have brought home a group of diplomats based in Guangzhou, China after they have been identified to be suffering from a mysterious illness that is similar to a brain injury that was also reported for US personnel in Cuba who had been brought home for a similiar case.
According to the statement of spokeswoman Heather Nauert, after they have confirmed one government employee had "suffered a medical incident" in Guangzhou, the department immediately sent a team to screen employees and their families in their consulate to see if others have also been affected by the problem.
Nauert said "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."
"Medical professionals will continue to conduct full evaluations to determine the cause of the reported symptoms and whether the findings are consistent with those noted in previously affected government personnel or possibly completely unrelated."
The New York Times reported that the State Department had evacuated at least two Americans who fell ill after hearing strange noises in China.
On Thursday, Chinese Foreign Ministry spokeswoman Hua Chunying said during the regular news briefing in Beijing, the government had not had any formal communication with US officials on any new cases and that it had investigated an initial incident.
"At present, there's been no discovery of clues or the reason causing the situation the United States mentioned," Hua said and added China is protecting diplomats according to international convention.
"If there's really a problem then the US side can directly contact the Chinese side and communicate, and China will continue to conscientiously investigate and coordinate with a responsible attitude."
Meanwhile, a US government official in China reported that there had been only one confirmed case in China, which was announced last month, and the State Department was offering screening to anyone in the US embassy or consulates in China who requested it.
Aside from Guangzhou, the US also has consulates in Chengdu, Shenyang, Wuhan and Shanghai.
Last year, 24 US employees and their family members based in Cuba displayed odd symptoms which was only seen in concussion and mild traumatic brain injury. The mysterious illnesses triggered tensions between the two countries, who used to be foes during the Cold War.
On Tuesday, US State Secretary Mike Pompeo released a statement that reveals that the department established a task force last month "to direct a multi-agency response to the unexplained health incidents".
"The precise nature of the injuries suffered by the affected personnel, and whether a common cause exists for all cases, has not yet been established."
