And as the week's violence here unfolded, other strains emerged.

That's right about the time that two new strains of norovirus emerged.

Flu viruses are always changing, and new strains emerge every year.

A similar strain of parties has emerged in the Baltic countries.

The longer the conflict goes on, the more strains in the alliance could emerge.

A different strain of critique has emerged from gender studies.

If a very lethal strain emerged in the Arctic, it would probably die out there.

If high-fat strains emerge, they are made available as well.

However, strains were emerging, with the band members apparently having different artistic views.

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