The rare respiratory virus that's hospitalizing children across the country continues to spread: 12 states have now alerted the Centers for Disease Control and Prevention of possible outbreaks. (Video via KMGH)

The virus, identified as enterovirus D68, was first reported in the Midwest but now might have spread as far east as North Carolina. It's sent hundreds of children to the hospital with flulike symptoms and breathing problems; some even had to be put it intensive care units. (Video via KSHB)

But what is enterovirus D68, and how worried about it should we be? Here's what we know so far.

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First, the basics: enterovirus D68 is a rare strain of enterovirus, a common type of virus which hits 10 to 15 million people in the U.S. every year. Usually, these infections result in nothing more than a strong cold, but this particular version has caused some nasty respiratory symptoms — very young or asthmatic children are particularly at risk from this virus. (Video via Fox News)

Previous outbreaks were confined to small clusters of people; this is the first mass outbreak of the virus on record. One scientist told The Washington Post, "We speculate that this virus in the past 10 to 15 years has sort of evolved into different sub types. ... Maybe it has mutated into something that is more easily transmissible, I don't know if that is the case but it's certainly possible."

There's no specific vaccine or treatment, but health officials say the disease can be prevented by common-sense hygiene — washing your hands and avoiding sick people will go a long way towards stopping the spread.

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And despite all the scary images this outbreak is generating, a contributor for The Daily Beast thinks the panic is a little overblown. He points to the last time this virus raised its head back in February, when it was linked to partial paralysis.

"That outbreak, too, flashed brilliantly across the headlines and created a similar legion of terrified parents who called worn-down pediatricians for support. Now, months later, few even recall that winter panic."

Fortunately, the illness isn't fatal; so far, no one has died during this outbreak, and most children who might have contracted the virus have recovered.