Not a medic, so I stand to be corrected, but short of heart attacks, strokes etc, are there many other illnesses where you can strap yourself in to the aircraft full of the joys of spring (with no signs of illness) and then be unconcious 45 mins later ?
In a word: Yes.
In several words: gastro-intestinal problems such as food poisoning and others can be very rapid in their onset and can have an incubation period ranging from within and hour of eating the food to a couple of days. We also live in a society where we eat more and more food prepared by someone else, be it a take away, a "ready meal" or similar and like most vital services ,our councils Environmental Health officers do a largly unrecognised and under-resourced job of keeping the worst stuff out of the food chain.