Well yeah, there IS always something.

But as I've never had bubonic plague or West Nile virus or leprosy, just worry about things that might actually effect you.

Although, I do reckon a lot of historical cases of dry (non-contagious) leprosy were actually people with late onset diabetes.
The symptoms are almost identical.
Nerve damage, increased chance of infection, loss of limbs.

What people don't realise is that in dry leprosy, loss of limbs is mainly down to damage caused because you have no feeling and don't realise you've damaged them.
Plus increased susceptibility to infection.

Given the peasant diet was primarily root vegetables and bread, basically just carbs.
Any poor Sod who's pancreas decided to quit would have been on the fast boat to the nearest leper colony as soon as the invisible demons began stabbing their feet with red hot knives.

I really wish I was making up the bit about the invisible demons