A very small virus that hits the stomach and gut. It makes people vomit a lot, and they often have diarrhoea as well; they feel weak and wretched for a day or two. It spreads with shocking ease — from hands, food, shared bathrooms, and close rooms — so you hear about it on cruise ships, in schools, and in care homes. You only need a tiny amount to fall ill, which is why washing hands matters more here than fancy medicine: there is no everyday pill that stops it, only rest and drinks. Though actually people in Taiwan often lump many stomach bugs together; this one is its own family of viruses, not “a cold in the stomach” and not the same as the enterovirus children get in summer. The name looks scientific, but it is just a place plus virus.

諾羅病毒（台灣說法；中國大陸較常說「諾如病毒」）