The technique reached its peak of sophistication in the early 20th century with malariotherapy, in which Plasmodium vivax, a causative agent of malaria, was allowed to infect already ill patients in order to produce intense fever for therapeutic ends.

This type of pyrotherapy was most famously used by psychiatrist Julius Wagner-Jauregg, who won the Nobel Prize for Medicine in 1927 for his elaboration of the procedure in treating neurosyphilitics.

[2] Wagner-Jauregg’s 1917 treatment method, also known as malariotherapy, involved the introduction of Plasmodium vivax malaria via injection into patients with advanced stages of syphilis.

[2] Advanced syphilitic infection can invade the brain causing neurosyphilis, affecting neural performance and function, which can in turn lead to general paresis of the insane (GPI), a severely debilitating mental disorder.

Doing so induced high-grade (103 °F, 39.4 °C or above) fever that was easily sustainable to eradicate invading spirochaetal bacterium Treponema pallidum, the pathogen responsible for syphilitic infection.