Cities in Europe used a range of methods to try and prevent the spread of disease. Venice quarentined newly arrived ships to ensure that any disease symptoms manifested and thus they knew which were infected.

In London, the city authorities organised clean ups of the streets, removing rubbish and dung from animals and stopping people from emptying chamber pots into the streets. This was because a common explanation for disease was that it was caused by "miasma" or bad air. Anything dirty or which smelled was considered to be a potential cause of disease and thus cities tried to clean them up. Smoke was believed to drive off the "miasma" so braziers and bonfires were lit in public areas.

Still in London (my area of expertise), when the disease reached its worst stages houses where the plague was known to be present were shut up and the inhabitants forbidden from leaving. A red cross was painted on the door to warn others against going in. To arrange speedy burial of corpses were buried in mass graves arranged by the authorities.

While not based on the knowledge we have now, medieval efforts at public health were logical and carefully thought through based on the medical expertise they had at the time. It is also important to remember that public health was not considered as part of the remit for local or national government at the time and resources available for it were very limited.