Basically this 38yo man got ill and was initially dismissed (he had some common cold symptoms). After a few days -however- his conditions got worse and since he had respiratory distress and his wife told the doctors he had dinner with someone who came back from China a couple of weeks before (though this person was tested negative) they decided to test him for Coronavirus and boom… POSITIVE! We tested thousands of people ever since.
At this point it’s possible that CV19 was already in Europe before we even started to check. In most of cases CV19 was probably mistaken for a seasonal flu and nobody made a big deal out of it. If patient 1 hadn’t got worse, he wouldn’t have been tested for Coronavirus and we wouldn’t have known about other cases, either.
Sorry but I find it hard to believe that in cities like London, Paris, Amsterdam etc. there is virtually no case of CV19. If other countries would test people like Italy is doing right now, they’ll probably find CV19- positives too.