The phrase "nasty flu" is correct and usable in written English.
Example: The entire office has been hit with the nasty flu, causing several employees to take sick days.
He's battling a nasty flu virus that threatens to derail his European tour.
Some nasty flu bug had beaten me, reducing your usual quirky, chipper columnist to a feverish, bedridden shadow.
An eavesdropper might have mistaken their references to Eton, the Observer, and a nasty flu bug for genteel chit-chat.
"Everyone caught a cold last year, but Five caught a particularly nasty flu," said Tim Westcott, an analyst at Screen Digest, a research firm.
That was the case for Gwyneth Paltrow, who, after five bouts with a nasty flu virus, decided it was time to take steps.
Mike Trout, OF, Angels – Blocked by Several Guys Trout, 20, is already behind this spring thanks to a nasty flu bug, so expect him to open the year in Class AAA.
We all know that contraception never fails; the pills work even if you have a nasty gastric flu, and increasing your body's intake of hormones is never problematic.
I'm not complaining, however, since several other members of our group came down with a nasty stomach flu on the return flight.
Then I had a nasty bout of flu.
IMAGINE that you had just recovered from a nasty bout of flu.
When the United States sneezed, Old Europe's banks caught a heavy cold, and New Europe's mini-tiger economies have succumbed, one by one, to a nasty bout of flu.
