who discovered infectious diseases are spread by microorganisms
Germ theory of disease Microorganisms are said to have been first directly observed in the 1670s by Anton van Leeuwenhoek, an early pioneer in microbiology. Yet Athanasius Kircher may have done so prior. When Rome was struck by the bubonic plague in 1656, Kircher spent days on end caring for the sick. Searching for a cure, Kircher observed microorganisms under the microscope and invented the germ theory of disease, which he outlined in his Scrutinium pestis physico-medicum (Rome 1658).[16] Building on Leeuwenhoek's work, physician Nicolas Andry argued in 1700 that microorganisms he called "worms" were responsible for smallpox and other diseases.[17]
History of syphilis It was observed that sometimes patients who developed high fevers were cured of syphilis[by whom?]. Thus, for a brief time malaria was used as treatment for tertiary syphilis because it produced prolonged and high fevers (a form of pyrotherapy). This was considered an acceptable risk because the malaria could later be treated with quinine, which was available at that time. Malaria as a treatment for syphilis was usually reserved for late disease, especially neurosyphilis, and then followed by either Salvarsan or Neosalvarsan as adjuvant therapy. This discovery was championed by Julius Wagner-Jauregg,[44] who won the 1927 Nobel Prize for Medicine for his discovery of the therapeutic value of malaria inoculation in the treatment of neurosyphilis. Later, hyperthermal cabinets (sweat-boxes) were used for the same purpose.[45] These treatments were finally rendered obsolete by the discovery of penicillin, and its widespread manufacture after World War II allowed syphilis to be effectively and reliably cured.[46]