Read for interesting historical background information Daniel Defoe's Journal of the Plague at London. You'll find it easily with Google, it's not an overly long read and it will give you a good feel on how people at that time coped with the plague which made so many victims, and how it evolved.

As for essential oils etc. - I already mentioned this somewher else recently - in France and other European countries when the plague hit Europe in the middle ages, the pharmacists or medics of the time, in order to be able to walk around in the streets amongst the dead and the sick, bore some sort of gas masks attached to their faces which were filled with aromatic herbs. They also used burning herbs (fumigations) for cleansing the air and getting it rid of the germs (although of course the existence of actual germs wasn't known yet).