The U.S. State Department confirmed Thursday that the number of American citizens suffering “health effects” from an unspecified attack at the American embassy in Havana, Cuba, has risen to 25.

Washington has yet to find a source for the defects, which a study in the Journal of the American Medical Association (JAMA) published in February described as mild brain damage, as well as physical and mental health defects. The case confirmed Thursday is the first since August 2017 to occur in Cuba, though the State Department confirmed a similar incident occurring in Shanghai, China, in May.

“On June 21st, following a comprehensive medical evaluation, one U.S. diplomat working at the U.S. Embassy Havana was medically confirmed to have experienced health effects similar to those that were reported by members of the U.S. Havana diplomatic community,” State Department spokeswoman told reporters Thursday. “This is the first medically confirmed case in Havana since August of 2017. The number of Americans now affected is 25.”

Nauert noted that one other embassy worker is still undergoing medical evaluations, and it is possible that a second person will be diagnosed with a medical condition as part of the mysterious string of attacks in the near future. She also told reporters that an unspecified number of Americans at the embassy requested medical evaluations to make sure that they, too, were not suffering the same health effects as their colleagues, but only one new case has been confirmed in Cuba since August.

Nauert did not provide any details as to the health defects the latest patient suffered, and has consistently refused to do so for any patient, citing medical confidentiality.

“We informed the Cuban Government of this occurrence on May the 29th of this year. The Cuban Government assured us that they will continue to take this seriously and are continuing their investigation,” Nauert added. “We strongly remind the Cuban Government of its responsibility under the Vienna Convention to protect our diplomats.”

Asked about whether the Cuban Castro regime has been forthcoming with information and helpful in uncovering the mystery behind these attacks, Nauert refused to “characterize it in any way.”

“I think our position on Cuba remains the same, and an investigation is still underway. We still don’t know to this date what is causing it and who is responsible,” she said, adding that the same goes for the situation in China. She also urged reporters not to “combine the issues” of China and Cuba and level blame on China based on the fact pattern in Cuba.

The State Department began to refer to the incidents as “attacks” during the tenure of Secretary of State Rex Tillerson, but have refused to provide any information on the context surrounding the diagnoses or what the embassy workers experienced before documenting headaches, short-term memory loss, and other concussion-like symptoms, according to the JAMA study. In October, the Associated Press published audio of a sound that it said the diplomats heard loudly in their rooms before beginning to suffer health effects, a shrill buzzing that at least one Cuban former political prisoner said resembled the sounds used to torture him in prison there.

That month, President Donald Trump told reporters that he believed Cuba was “responsible” for the attacks on the diplomats. The State Department withdrew all non-essential staff from the embassy, which only reopened under President Barack Obama for the first time since the violent Cuban Revolution in 1959.

Havana’s communist regime has denied any involvement in the attacks, first promising to work in tandem with the U.S. government to find the source of the attacks, then claiming the attacks never happened. Cuban Foreign Minister Bruno Rodríguez described the incidents as “science fiction,” and a feature-length report on Cuban state television concluded that the diplomats heard cricket noises in their homes and thought they were being attacked. Senator Jeff Flake (R-AZ), a consisted defender of the Castro regime for years, told reporters that he did not believe evidence existed that the attacks occurred in January.

The JAMA study concluded that it was impossible for the patients studied to have fabricated what occurred to them and that their symptoms were not psychosomatic.

At press time, neither Cuban state media nor the Cuban Foreign Relations Ministry (MINREX) has responded to the announcement of a new case of injuries in Havana.