The US embassy in China issued a new health alert for its citizens on Friday after more US government employees were evacuated from the country over fears they may have been hit by a mysterious illness.
American officials sent a medical team to the southern city of Guangzhou last month after an employee attached to the consulate there was diagnosed with brain trauma after experiencing strange sounds.
The case revived fears that a US rival has developed some kind of acoustic or microwave device after similar symptoms were reported among American diplomats and their families in Cuba in 2016.
The US embassy’s latest health alert, the second in two weeks, said that following voluntary medical screenings, the State Department “has sent other individuals to the United States for further evaluation”.
The message urges staff and family members to contact their health care provider if they experience “any unusual, unexplained physical symptoms or events, auditory or sensory phenomena, or other health concerns”.
“Symptoms to be attentive for include dizziness, headaches, tinnitus, fatigue, cognitive issues, visual problems, ear complaints and hearing loss, and difficulty sleeping,” the alert says.
The message urges people to “not attempt to locate the source of any unidentified auditory sensation” and instead move to a different location.
The cases come at a sensitive time in relations between the United States and China, with the two nations locked in negotiations aimed at preventing a trade war and tensions over Beijing’s claims to the South China Sea.
The State Department, which reported the latest medical evacuations on Wednesday, has not accused any particular country or organisation of being behind the latest incidents.
The Chinese foreign ministry said Thursday that its investigation into the first case has not yielded any clues as to the cause of the incident.
“As for the latest incident, my understanding is that the US side hasn’t had any formal communication with the Chinese side about it,” foreign ministry spokeswoman Hua Chunying said Thursday at a regular press briefing.
The State Department has previously said brain injuries suffered by 24 US officials and family members posted in Havana could have been the result of a “health attack”, perhaps from an unidentified secret weapon.
Washington has said in the past that Cuban authorities must take responsibility for the safety of US diplomats on their soil, but the Havana government denies any knowledge of an attack.
The US has set up a task force to oversee the response to the mystery ailments among diplomats in China and Cuba.