I’d find family plots that would have 3-4 kids all dying within a few months of each other.

Worse still, in places like New England, when one family member would die right after another – after another – after another – they’d attribute this to vampires, burning the bodies of the recently deceased to ensure they could not come back, and on occasion using some of the burnt bits as a “preventative” for the living to consume so as to not be taken themselves. It didn’t work.

It wasn’t until the late 19th century they finally figured out that tuberculosis (aka “consumption”) is a bacterial disease that is extremely communicable in tight quarters, and that the living who nursed the recently dead would naturally be next because it’s a disease they caught from nursing their own sick.

And even then a number of them held on to old beliefs, long after others had figured it out:

When rural Rhode Islanders moved west into Connecticut, locals perceived them as “uneducated” and “vicious”, which was partially due to the Rhode Islanders’ beliefs in vampirism. Newspapers were also sceptical, calling belief in vampirism an “old superstition” and a “curious idea”. 

The only reason we are not now dealing with tuberculosis on a wide scale is because of – anti-vaxxers cover your eyes – vaccines, though it too is now coming back, and in drug-resistant forms.

I’m sure you already know all this working in old cemeteries, but I thought I’d mention it: superstition to fill in the blanks and address fear goes back as far as time immemorial.