Final answer:
Malaria was used to treat syphilis in the early 20th century because the high fevers it caused were able to kill the syphilis bacteria. After the syphilis was cleared, the malaria was then treated. This is not practiced today due to the development of safer treatments.
Step-by-step explanation:
In the early 20th century, malaria was sometimes used to treat patients with syphilis, a sexually transmitted infection caused by the spirochete Treponema pallidum. This approach, known as malariotherapy, involved intentionally infecting a syphilis patient with the Plasmodium parasite that causes malaria. The reason for this seemingly dangerous treatment is that the high fevers caused by a malarial infection could, in fact, kill the syphilis bacteria. The thermal effect of the fever causes an unfavourable environment for the spirochete, leading to their death. After syphilis was cleared from the patient's system, the malaria could then usually be treated effectively with quinine, an anti-malarial drug. It's important to note that this was a last resort treatment and it is not employed today due to the development of safer and more effective antibiotics such as penicillin.
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