Hans Zinsser was the youngest son of a German immigrant who owned a chemical products company in New York, New York. After a privileged childhood including private schooling, study abroad, and European travel, Zinsser attended Columbia College where his poetic imagination flourished along with his scientific curiosity. When it came time for him to decide on a profession, he chose science and earned an M.D. and M.A. from the College of Physicians and Surgeons of Columbia University in 1903. He became a professor of bacteriology and immunology at Stanford University in 1911, moved to Columbia in 1913, and then to Harvard Medical School in 1923.

Zinsser's interest in the epidemiology of infectious diseases led him to join the American Red Cross Sanitary Commission on its mission to Serbia in 1915 where a typhus epidemic had broken out. His investigations of typhus also took him to the Soviet Union in 1923, Mexico in...