Such patients require 'close monitoring for the development of life-threatening complications,' they say.

Don't hang about, because you're at risk of life-threatening complications, which means you need to be in hospital, pronto - call an ambulance.

And although rare, life-threatening complications are often unpredictable.

Or the likes of bird flu, measles and mumps - all of which can range from the mildest of symptoms to life-threatening complications?

There are many life-threatening complications.