It would seem that just one look at Dr. Wagner-Jauregg might be enough to scare the spirochetes right outta you! More observations:

1) Syphilis was certainly the underreported scourge of the 17th-20th Centuries, often treated by Mercury (which initially had some efficacy, but later tended to poison the patient). The saying of the day was "5 minutes w Venus meant 20 yrs w Mercury". I suspect many old sanitariums had syph patients (a kind of coverup). Condom invention in late 1800s must've been a boost to prevention.

2) There is some recent news re: Macrophage therapy (also popular in early 20th century, before penicillin) as an alternative to antibiotics, to which many bacteria are becoming resistant. Interesting the "war" between bacteria, viruses, protozoans, etc and how one might be used against another.

3) I'm also interested in why this worked, Syphilis is a bacterium, malaria a plasmodium protozoan, somehow in competition for hosts, malaria disrupts the spirochete's life process?

4) In the "Wild West" of microbiology & epidemiology (eugenics movement, experiments on mental patients, Imperial Japan, Nazi Germany, etc) last Century, many weird & cruel experiments but some interesting findings...darn those medical ethics!