Transcript for Concerns over mystery ailment at US consulate

Now to that medical mystery, Americans working at a U.S. Consulate in China getting sick facing symptoms typical of traumatic brain injury similar to what happened at the U.S. Embassy in Cuba two years ago. James Longman is tracking it from London. There are concerns that this could be a type of attack. Reporter: That's right, Amy. This is a very strange case. It's a crisis affecting the biggest U.S. Consulate in China with Americans there apparently suffering from a mystery illness. Workers and their families in the southern city there say they're experiencing dizziness, fatigue and one heard marbles being rolled around inside a tunnel. The state department says they're the kind of things caused by a concussion or minor traumatic brain injury. Several Americans have been evacuated now to the U.S. For evaluation and this case gets even more strange because as you say these complaints are similar to what happened in Cuba in 2016 when 24 Americans at the U.S. Embassy in Havana fell with similar symptoms and that's still being investigated. The big question, is this just an illness or a deliberate attack? If so, who is responsible? The Chinese are saying they have absolutely no idea what is causing all this. They say an investigation into the first reported illness in may came up with nothing and they're prepared to launch another one and work with the U.S. To find out what's going on. Bizarre and frightening. James Longman, thank you very much for that.

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