Max Theiler (pronounced Tyler) was born on a farm near Pretoria, South Africa, on January 30, 1899. He enrolled in a two-year premedical program at the University of Cape Town in 1916. In 1919, soon after the conclusion of World War I, he sailed for England, where he pursued further medical training. Despite this rigorous training, Theiler never received the M.D. degree because the University of London refused to recognize his two years of training at the University of Cape Town.

Theiler was frustrated by the ineffectiveness of most medical procedures and the lack of cures for serious illnesses. After finishing his medical training in 1922, the 23-year-old Theiler obtained a position at Harvard Medical School. His early research focused on amoebic dysentery and rat-bite fever. From there, he developed an interest in the yellow-fever virus.

Yellow fever is a tropical viral disease that causes severe fever, slow pulse, bleeding in the...