According to the material, which two scientists are credited with building upon Snow's germ theory?

• A. Ignaz Semmelweis and Koch
• B. Koch and Edward Jenner
• C. John Snow and Ignaz Semmelweis
• D. Edward Jenner and John Snow

Answer: (A)

Snow’s germ theory showed that diseases can spread through microorganisms in the environment, setting the stage for understanding how infections move from person to person. Building on that, Ignaz Semmelweis demonstrated that transmission can be interrupted in clinical settings by simple practices like handwashing and proper instrument hygiene, which drastically reduced maternal mortality from puerperal fever. This work translates the theory into a concrete method for preventing disease transmission. Koch then took the idea further by linking specific microbes to particular diseases and establishing the steps to prove causation, which solidified the microbial basis of disease and clarified the mechanism behind Snow’s general idea. Jenner’s vaccination work, while pivotal in immunology, predates and isn’t a direct extension of Snow’s transmission-focused germ theory, so it doesn’t fit with the idea of building upon Snow’s concepts in the same way Semmelweis and Koch do.