The development of the field of epidemiology and the introduction of vaccines and antibiotics in the 20th century have greatly reduced the number of people affected by infectious diseases. In fact, today some diseases such as polio have been reduced to just several thousand cases a year, and smallpox, a disease dreaded for centuries, has been eradicated.

Test Your Knowledge

Who am I? Proved that microorganisms cause fermentation and disease. Pioneered the use of vaccines for rabies, anthrax, and chicken cholera. Saved the beer, wine, and silk industries of France and other countries. Performed important pioneer work in stereochemistry.

Who am I? Scottish bacteriologist. Discovered penicillin in 1928. Shared the Nobel Prize for Physiology or Medicine in 1945 with Ernst Boris Chain and Howard Walter Florey.

Who am I? American virologist who shared the Nobel Prize for Physiology or Medicine in 1975 with Howard M. Temin and Renato Dulbecco. With Temin, discovered reverse transcriptase, an enzyme that synthesizes DNA from RNA. Conducted research that led to an understanding of the interaction between viruses and the genetic material of the cell.

What am I? Microscopic single-celled organisms that live in enormous numbers in almost every environment on the surface of Earth. Lack a membrane-bound nucleus. Widely used in the preparation of foods, chemicals, and antibiotics.

What am I? An infectious agent of small size and simple composition. Can multiply only in living cells. Not a plant, animal, or bacteria.