Vienna, Austria(CNN) Austrian authorities said they are investigating reports that US diplomats in Vienna have experienced symptoms of a mystery illness known as Havana Syndrome.
"We take these reports very seriously and, according to our role as the host state, are working with the US authorities on a joint solution," the Federal Ministry of European and International Affairs said Sunday.
"The security of diplomats dispatched to Austria and their families is of utmost priority for us," the ministry added.
A US State Department spokesperson said Saturday: "In coordination with our partners across the US Government, we are vigorously investigating reports of possible unexplained health incidents among the US Embassy Vienna community or wherever they are reported."
Victims of Havana Syndrome have reported a varying set of symptoms and physical sensations, including sudden vertigo, nausea, headaches and head pressure, sometimes accompanied by a "piercing directional noise." Some reported being able to "step in" and "step out" of these sensations by physically moving their bodies elsewhere. Some have been diagnosed with traumatic brain injuries and continue to suffer from debilitating headaches and other health issues years later.
Since the incidents began in late 2016 in Cuba, US federal investigators have struggled to determine what -- or who -- is causing the mysterious symptoms. There have been cases reported in Russia, China and elsewhere across the globe, and a Senate committee said in April that the number of suspected cases appeared to be on the rise. In April, CNN reported on two separate incidents that occurred near the White House late last year affecting National Security Council staffers.
In May, two defense officials said the Pentagon was drafting a memo to the entire US military and civilian workforce asking personnel to report any so-called anomalous health symptoms that might indicate they have been victims of Havana Syndrome, which has struck US diplomats, spies and military personnel around the world in recent years.
No final decision has been made on whether to issue the memo, but the fact it's being considered underscores the growing concern at the Pentagon's senior levels that they need to gather more information on the illness.