Early in the colonial period, the westerners thought god was killing the so called non-believers and savages. In some cases, many natives even caved in and converted to Christianity or Catholicism in hopes of being cured.
The sad thing to was that Small Pox takes a few days to incubate in your body, but at the same time you can still be contagious without showing symptoms. You could be a fur trading, trade some pelts to some Europeans, and the come home and infect everybody without even knowing it. Then after coming home someone who is infected, but doesn't know it yet goes out to trade with another tribe, and another, and another.
Much later, almost everyone knew somewhat about microbes. A British/American army officer(can't remember which) actually used contaminated blankets against the natives to infect them with small pox. Even during the medieval ages the Mongols would catapult sick people over walls and fortifications.
Sure herbal medicine might be more accessible to this who lack access to modern medicine, even modern medicine has its faults. I think must of us would rather ingest some sort manufactured tablet instead of smoking some sort of toxic walnut from south America to cure constipation. I definitely have more faith in radiation killing cancer cells than marijuana being the miracle plant.
