Final answer:
Ignaz Semmelweis is credited with first recognizing the importance of handwashing in preventing disease, with significant further contributions by John Snow and Joseph Lister in sanitation and epidemiology.
Step-by-step explanation:
The person who first recognized the importance of handwashing to prevent the spread of disease agents was Hungarian physician Ignaz Semmelweis. Semmelweis observed that the incidence of puerperal fever could be significantly reduced when physicians washed their hands with chlorinated lime water before and after examining patients.
Although his findings were initially met with resistance, they laid the groundwork for our current understanding of handwashing as an essential practice for preventing the transmission of diseases.
Moreover, British physician John Snow and British surgeon Joseph Lister also made significant contributions to the field of sanitation and epidemiology, with Snow identifying contaminated water as the source of cholera and Lister implementing strict cleanliness and disinfection protocols in surgery, which dramatically reduced post-surgical infection rates.