They are like a bad virus, Fleetlord; they mutate--not physically, but technically, which is worse--too fast, maybe faster than we can handle.

American counterintelligence eavesdropping picked up a Soviet agent warning Mr. Bloch, "A bad virus is going around and we believe you are now infected."

'The trouble is that even when it's a bad virus it always looks like 'flu - and remember, the polio itself dies out in about a week.

We're only going to have more bad viruses coming down the road," Dr. Weiss said.

Another is that a coronavirus changed for the worse by trading genetic material with another virus.

Mr. Arafat has appeared frail during brief public appearances in recent days, but aides and doctors insist that he is suffering only from a bad intestinal virus.

"Marburg is a very bad virus, even worse than Ebola," he said.

Seemingly oblivious to the wonders of Auto-Tune, Black's nasally warbling became embedded in the brain like a bad virus.

There are a couple bad viruses now that are modifying the boot sector and installing themselves before the rest of the system gets going.

Many worse viruses and worms are expected soon.