To force it out of this body would put a dangerous strain on the other.

That flu strain, named for where it originated, is one of the more dangerous strains.

I wonder if the difference in that makes some wild strains so dangerous has been figured out.

Given a large pool, immensely dangerous new strains can emerge, and should that happen they will not necessarily stay put.

So, the authors said, consistent condom use may protect women against other dangerous strains of the virus.

"There are other government and contractor facilities that do classified work with access to dangerous strains," the official said.

Overdoing it can put dangerous strain on your body.

The new strains, more dangerous and aggressive than the old strain, spread rapidly, either carried by the wind or in seed potatoes, he said.

TB is coming back fast, in very dangerous strains that are resistant to most antibiotic treatments.

Yet he, too, voiced a lack of surprise at the possibility that a more dangerous strain had emerged.