Why did one epidemic after the other ravage London and other European cities, while Tenochtitlán - a city much bigger than most cities at the time - didn't really experience anything like that until 1519?

by Worried_Abrocoma

European cities were repeatedly hit by plagues and disease, while Tenochtitlán first saw these epidemics with the arrival of the Spanish. How come there weren't major epidemic outbreaks of disease before that in Tenochtitlán?

ronniethelizard

I have a related question:

Would we know if diseases had ravaged Tenochtitlan prior to the arrival of the Spanish and if so, how?