Honestly, you think a terrorist in the throes of gut-spilling diarrhea and vomiting is going to be making a circuit of the continent?
Who said a circuit of the continent? But any jihadist willing to blow himself up to kill a handful of infidels will be thrilled at the chance to indirectly kill millions, just by riding a subway while infectious.
What makes you think they would NOT? They will behead children, rape little girls and boys, but suddenly being sick will stop them in their tracks? Really?