Colombia’s president says he is aware of cases of the mysterious illness known as “Havana Syndrome” being reported at the U.S. Embassy in Bogotá — one of the largest U.S. embassies in the world, hosting diplomats, intelligence agents and aid workers.

“Of course we have knowledge of this situation, but I want to leave it to the U.S. authorities, who are conducting their own investigation, because it is about their personnel, to clarify,” President Iván Duque told reporters in New York on Tuesday.

News of the suspected cases comes about a week before Secretary of State Antony Blinken’s planned visit to Bogotá.

At least five families with links to embassy staffers were afflicted in recent weeks, with one family leaving the country for treatment, according to the Wall Street Journal, which first reported the cases.

The State Department said in a statement to The Washington Post that it “vigorously” investigated reports of such incidents wherever they were reported, including “whether they may be attributed to a foreign actor.”

“Due to privacy concerns and for security reasons, we do not discuss specific reports or Embassy operations, but we take each report we receive extremely seriously,” the statement said.

The exact origins of the illness remain unknown, although its name dates to 2016, when it first appeared to hit CIA officers and Canadian personnel in Cuba’s capital, Havana. The initial cluster confounded medics, with victims reporting the sudden onset of a range of symptoms such as headaches, nausea and memory loss. Brain scans later showed tissue damage usually seen in patients with concussions after a blast or car accident.

Signs of it have since popped up in Russia, China, Colombia, Uzbekistan and the United States. German police confirmed last week that the country was looking into an “alleged sonic attack” targeting U.S. Embassy staffers in Berlin, among roughly 200 cases among U.S. diplomats and intelligence officers around the world.

President Biden has just signed legislation to give financial aid for brain injuries to victims of Havana Syndrome, pledging on Friday to “get to the bottom of these incidents.”

The bill comes after symptoms consistent with the illness showed up last month in the team of CIA Director William J. Burns, who tasked a top agency official this summer with leading the investigation into the mysterious illness.

In another sign of the growing attention the illness is attracting, the spy agency removed its station chief in Vienna after criticism of the response to purported cases at the U.S. Embassy in Austria.

Read more: