A US State Department spokeswoman said on Thursday that at least 16 people at the US Embassy compound in Cuba have had a mysterious health symptom.
"We can confirm that at least 16 US government employees from our embassy have had some symptoms," said spokeswoman Heather Neuert. "They have received medical treatment in the United States as well as in Cuba."
Many of the US government agencies and departments are investigating these incidents and "taking them seriously," Noiret said.
The New York Times reported that health symptoms may be caused by ultrasound devices used in the homes of embassy staff.
Nuert said the Americans began to experience these symptoms in 2016 and told embassy staff.
"We are working hard to try to provide care for our parents there - they are on an official mission - and we are trying to provide them with the care, treatment and support they need," she said.
The US government said earlier this month that an "accident" last year in Havana had wounded US diplomats with "a variety of physical symptoms." The Canadian government said at least one of its diplomats in Cuba had been treated in hospital after suffering "unusual" symptoms, including headaches and hearing loss.
Washington expelled two Cuban diplomats in response to the incident.
Former US President Barack Obama re-established diplomatic ties with Cuba and the embassy resumed operations in 2015.
President Donald Trump took steps to reverse some of Obama's reforms toward Cuba, but he kept the embassy open in Havana.