Sept. 2 (UPI) -- The U.S. State Department said more diplomats in Cuba have suffered symptoms following a new "acoustic attack" in August.
State Department spokesperson Heather Nauert said 19 Americans were confirmed to have been affected by the "sonic harassment attacks," up from 16 last month.
"We can confirm another incident which occurred last month and is now part of the investigation," Nauert said. "We can't rule out new cases as medical professionals continue to evaluate members of the embassy community."
The United States and Cuba began probing the apparent "acoustic attack" conducted using ultrasound energy after two Cuban diplomats were expelled from the Cuban embassy in Washington, D.C., in May.
U.S. officials originally said the attacks on U.S. diplomats dated back to December 2016 and ended in late spring, but the new incident in August is now subject of an ongoing investigation.
The American Foreign Service Association has met or spoken with 10 victims, as some of the others were unavailable or remained at their posts in Havana.
"Diagnoses include mild traumatic brain injury and permanent hearing loss, with such additional symptoms as loss of balance, severe headaches, cognitive disruption, and brain swelling," the association said. "AFSA strongly encourages the Department of State and the U.S. Government to do everything possible to provide appropriate care for those affected, and to work to ensure that these incidents cease and are not repeated."
Nauert said no device or piece of equipment has been discovered yet, but the government is committed to solving the mysterious cases and caring for the affected diplomats.
"What has happened there is of great concern to the U.S. government," Nauert said. "Let me just reassure you that this is a matter that we take very seriously ... It is a huge priority for us and we're trying to get them all the care that they need."