Discovery of Viruses

Viruses redefined the boundary between life and non-life. The 1892 discovery by Dmitri Ivanovsky and Martinus Beijerinck unveiled filterable agents 100–1,000 times smaller than bacteria, challenging fundamental definitions. This discovery explained diseases like polio and rabies, and today over 200 million viral infections (e.g., COVID-19, HIV) are diagnosed globally each year, underscoring its monumental public health impact.