This reminds me of an episode of one of my favorite podcasts,
Radiolab. This podcast
used to be about science. (Lately, the podcast leans more towards the hosts' personal political opinions.)
Anyway, this particular episode was about two friends who were both Viking enthusiasts. As in, they were into Vikings the way that posters on this board are into the Civil War. One of these women just happened to be a microbiologist. The other woman was a historian. The women came across an approximately 1,000-year-old book of Viking medicine. This was by no means a formal scientific study, but they "made" one of the cures listed in the Viking medicine book, and then tested it against a sample of a staph infection. The Viking medicine appeared to kill the infection.
Again, this was no scientific study.
However, the podcast speculated that the treatments listed in this book of Viking medicine went out of use because their effectiveness diminished because the infectious diseases evolved to be resilient against them. So, as time went by, people stopped using these treatments. Then, as the diseases evolved further, the diseases in turn stopped being as resilient to the treatments. This is why the one treatment "worked" against an infection in this non-scientific experiment.
Here is the podcast episode and the transcript.
Staph Retreat