Max Theiler

Max Theiler (1899-1972), South African virologist and Nobel Prize winner who made major contributions to research on the viral disease known as yellow fever. During the 1930s he developed vaccines that protected millions of people from this incurable tropical affliction. For his contributions, Theiler was awarded the 1951 Nobel Prize in physiology or medicine.

Born in Pretoria, Theiler studied medicine at the University of Cape Town, leaving for England in 1919 for Saint Thomas's Hospital Medical School, London, where he completed his medical training in 1922. That year, he moved to the United States, joining the Department of Tropical Medicine at the Harvard Medical School. In 1930 he accepted a post with the Rockefeller Foundation in New York City. He remained with the foundation until 1964, when he became professor of epidemiology at Yale University, New Haven, Connecticut.

At Harvard, Theiler's early research interest was in amoebic dysentery, but he soon switched his efforts to yellow fever. This disease, characterized by high fever, slow pulse, and vomiting, can fatally damage the liver and is caused by a virus (in fact, it was the first disease for which researchers, in 1926, identified a viral cause). Most victims recover and develop immunity against subsequent infection, but earlier in this century the disease was fatal in roughly 10 percent of cases in Africa and equatorial tropical regions in the Americas. An important finding during the 1920s was that monkeys could be infected with the virus and then used for experimentation. Theiler, in a major advance, demonstrated that mice could serve as a much more convenient and inexpensive experimental model.

Using mice, he developed highly efficient methods for breeding the yellow fever virus as he pursued various strategies for vaccines. In 1934 Theiler developed a vaccine based on an “attenuated,” or weakened, form of the virus cultivated in mice. Scratched into the skin, the virus would not cause yellow fever, but would provoke the body's immune system to protect against any subsequent infections. Because this vaccine sometimes caused encephalitis, an inflammation of the brain, Theiler continued to refine his vaccine experiments. In 1937 he introduced another vaccine, designated 17D, based on another strain of the virus that was grown in chicken embryos. Between 1940 and 1947 the 17D vaccine was used to protect more than 28 million people in Africa and the Americas. Today, although still a problem in remote areas, yellow fever has been vastly reduced as a health threat.

In addition to his Nobel Prize, Theiler received the Albert Lasher Award in 1945. Theiler remained in the United States for the rest of his life; however, he never became a U.S. citizen.