When people travel long distances, it’s not uncommon for them to get some kind of illness upon arriving. But it seems like the locals are rarely sick at the same frequency. Why is that?
Beats me! But maybe it’s because the immune systems of the local residents are already “tuned” for local conditions. Let’s go with that!
Before traveling to a certain area, perhaps a person could order a bunch of barely-processed or even entirely unfiltered water from a certain area (Figure 1). Then, if the theory in the “background” section is correct, by drinking it, they should 1) possibly get sick and 2) be less likely to get sick upon actually arriving at their new travel location.
There’s probably substantial actual medical research that’s been done on this topic, but reading that and presenting an actually-informed proposal would be antithetical to the Worst Plans mission.
PROS: It’s a tradeoff: possibly be sick now instead of later. Possibly worthwhile for short trips?
CONS: It is possible that it would be better for a traveler to just avoid the local water (and uncooked food) entirely. Also, this proposal might not even work, in which case a person would just get some exotic water-borne disease for no benefit whatsoever!