A few things about whooping cough:
1) Some of my friends have recently had it.
2) Some of them were not vaccinated against it.
3) It's only dangerous for infants.
4) It is treatable with antibiotics and as soon as you start taking them you are no longer contagious.
5) My children have not been vaccinated against it, it's present in our small community and we have yet to become infected.
6) The cough sounds pretty nasty and goes on for months.
The explanation requiring the fewest assumptions is the most likely to be correct. -- William of Occam