These were pre- Spanish Flu, most of the dates were in the early to mid 1800's. I'd guess smallpox or cholera, but that's just a guess.
I have an uncle who was doing our family genealogy and we went to a cemetery to find a grave for a relative who died at the time of the Spanish flu. They couldn’t give us an exact location, just a general spot in the cemetery. Turns out, in that area, there were no markers, because they were mass graves for the influenza victims.
I have a letter from a relative who was dying of cholera during the Civil War. She wrote about other family members who had succumbed. Very sad.