I've been toying with a story of person sent to a alternate reality that mirrors medieval Europe, but not necessarily with identical history/countries. The time traveler would earn the trust/support of the youngest prince, but the prince's father, the king, still suspects him to be a charlatan and distrusts his 'future' knowledge.
I want the time traveler to finally be tested by being asked to help 'cure' a disease rapidly spreading in a nearby country. I've attempted a question on this topic before, but I was told my theoretical disease wasn't realistic, so now I'm asking for a realistic disease that he could help cure.
I don't want this disease to be one he happens to just remember the cure for, as I want him to have to work at it. This pretty much rules out the Black Plague, and I'd prefer to avoid creating any plague similar enough to Black Plague for readers to see it as a Black Plague knock off. I have considered smallpox, with his remembering cowpox was used as the first vaccine for it, but I'm honestly not sure how he would handle reliable infecting a population with cowpox and am also not sure if he can convince the king(s) to support the action, basically I'd prefer some other option, one where he has to use his knowledge of scientific method and how disease spreads to come up with a means of pinpointing how it spreads and prevent it.
The obvious answer is to tell everyone to use proper sanitation, but I don't want to go that route either. He has told everyone about proper sanitation, but people are resistant to the ideas. Doctors hate the idea of being told their a major spreader of disease and can't be talked into using boiled water to wash their hands (which is something that definitely happened back when sanitation was first recommended), and the king is not convinced of our Travelers reliability enough to be willing to fund expensive sewer or aqueducts on his say so. Basically he doesn't have the political clout to convince many people that sanitation is important yet, and it's hard to prove the benefits of sanitation definitively if he can't convince people to try it. Also, while sanitation is important, it's not as obvious a cure. I want the Traveler to find a cure that is undeniable to back his credibility up. Something as definitive as "these fleas spread the disease, kill all the rats and look the disease isn't spreading, there can be no doubt that this is the solution."
The Traveler is not a doctor and does not have a medical degree. He is however intelligent with a relatively wide breadth of knowledge in science. He also has an interest and more thorough depth of knowledge in evolution in particular, which has enough overlap with biology and evolution of disease to have some idea of how to handle disease.
I am therefore looking for a plausible disease that he can cure which fits a few criteria.
- The disease is new and spreading rapidly enough to have drawn the attention, and concern, of local kings
- He can find a 'cure' to, be that a way to minimize it's spread or treat those already infected
- The cure is definitive and obvious enough that he can convince everyone to support it despite the king's initial skepticism of him.
- He could plausible figure out a means to address the disease with his limited medical knowledge and scientific method, ideally without his requiring too massive an expense or logistical exercise to discover the cure (the king of the country infected is desperate enough to support our Traveler's efforts to some extent, but his king's skepticism still means that support is limited)
- is not something he cures just by remembering how it was cured in the past
- His cure can't just be to tell everyone to practice better sanitation.