Oh for heaven's sake!  I'm not a bloody vet.  Look, I'll see about arranging a vaccination.  In the meantime, keep well wrapped up, drink plenty of water and if you should bump into Sensible Barry in the street, don't let him borrow your comb.  ( Comb - get it?   Chickens... combs... It's kind of a joke, you see.  Oh forget it.  You try to introduce a bit of light-hearted humour into the proceedings and where does it get you?  It's not easy telling someone they're going to die, you know...)