I may be mistaken (and you can correct me if I am wrong} but during the Black Plague fewer Jews than gentiles died and that was due to the fact of bathing in the Mikveh.    

In the 19th century there were regular outbreaks of Cholera at European ports. In 1892 there was a major one in Hamburg. In 2012 my colleague Howard Wolinsky of Chicago made a programme for the BBC on how his ancestor had travelled in 1892 from Kovno to Hamburg, and from Hamburg to Hull, Hull to Liverpool, and Liverpool to Boston. His claim to fame was that he sailed from Hamburg to Hull on the very last day Hamburg was open - the next day it closed due to the Cholera epidemic, and remained closed for some months. At the Hull end this had an impact on my ancestors, whose sons made extra pennies by directing new arrivals to shelters and the railway station.

It was not only Cholera, but Typhoid,  that also had an impact at around the same time. My grandfather's elder sister died of typhoid in 1894 in North Wales - she was only 26. She and her husband and my grandfather had been sent there from Liverpool by my great grandfather to offer financial services to local farmers. There were no other Jewish people in the area, so they probably would not have eaten kosher meat - infected meat was a source of Typhoid. My great grandparents ended up caring for Leah's three childen, one of whom was aged only one year old. Her husband remarried and emigrated to Chicago a few years later, leaving his children behind (though two of them later joined him in USA as adults).

So our ancestors have long had to battle with outbreaks of serious disease.

Jill Whitehead, Surrey, UK