ARI SHAPIRO, HOST:
Cuban officials said yesterday they can't figure out what's behind a range of health problems for U.S. diplomats and their families. That came after the U.S. withdrew two people from the embassy in Havana last week on top of more than 20 people who were recalled last year. And U.S. diplomats in China were brought home, too, experiencing similar symptoms. Some of them reported hearing odd noises.
We're going to talk about the science behind this mystery with NPR's Jon Hamilton. Hi, Jon.
JON HAMILTON, BYLINE: Hey.
SHAPIRO: Remind us what happened with these U.S. diplomats in Cuba and China experiencing these odd symptoms.
HAMILTON: Well, the symptoms were kind of like those associated with a concussion. So you had people talking about headaches and dizziness, and then there was hearing loss. Now, hearing loss is not necessarily something when you get whacked over the head. But for instance, a concussion caused by a blast wave can cause hearing loss. So that's what we're hearing.
SHAPIRO: And there's been speculation that this could have been some kind of sonic attack. Other people have said maybe it could have been some kind of crude audio surveillance technology. How likely is that?
HAMILTON: I guess the answer is it's theoretically possible. But it's hard to imagine the circumstances under which it could have occurred. So you have weapons that are called sonic cannons, for instance, that fire very loud, very audible sounds, cause pain. They're mostly used to fend off pirates on the open seas. But you would know if a weapon like that was used. And then you have ultrasound, which is sounds that are too high for us to hear them. And in fact, doctors sometimes use ultrasound to kill bits of brain tissue if they're causing a problem. But ultrasound is really hard to even get through a patient's skin and bone, let alone through a wall or a window or something where it could hurt somebody. So another possibility...
SHAPIRO: Uh-huh (ph).
HAMILTON: ...Is the other sounds we can't hear, the really low sounds - infrasound, we call it. It's too low to hear. And it also can cause physical damage. But it would take an enormous loudspeaker. So again, not super stealthy.
SHAPIRO: So you're saying it's unlikely that it was this sort of sonic attack. It's unlikely that it was very high or very low sounds. Is there anything that we can learn by looking more closely at the symptoms that people have experienced?
HAMILTON: Well, one of the problems with concussion is that it is diagnosed by the symptoms. So if you're dizzy and you have - you know you got hit on the head, then the doctor says, oh, you had a concussion. You can do MRI scans of people, which I understand was done on many of the people from Cuba, but MRI does not show most concussions. There is one very sophisticated type of MRI called diffusion tensor MRI which can show problems, subtle problems in the white matter of the brain. These are the information highways. But it's unclear whether that's been done on anybody from Cuba or, even if it was done, whether it would show this kind of problem.
SHAPIRO: So what are the other possibilities here that might have caused this?
HAMILTON: I mean, vague symptoms like these can be caused by all kinds of things. It could be an infection. It could be antibiotics which are known to cause hearing loss, brain disease. Or it could even be poison. So there are all these other alternative physical explanations. And then there is also the psychological explanation, which is something called mass psychogenic illness. And that is when symptoms spread through a group even though there is really no physical cause for them.
SHAPIRO: Does psychogenic mean it's all in your head, or is it real?
HAMILTON: It's real to the people who experience it. The symptoms feel just like they would if they had a physical cause, but they don't.
SHAPIRO: A real mystery, I guess, still unsolved.
HAMILTON: Still unsolved.
SHAPIRO: NPR's Jon Hamilton, thank you.
HAMILTON: You're welcome.
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