Clara Maass and the Yellow Fever Conundrum

An Army nurse makes the ultimate sacrifice for the betterment of science and humanity.

Clara Maass (L) featured on a 13-cent stamp. A painting (R) depicting yellow fever in 1871. Public Domain

After caring for disease-ridden soldiers as an army nurse, Clara Maass became intrigued with the yellow fever virus and finding a cure for it. To help scientists better understand the disease, Maass volunteered to get infected with it. Unfortunately, the second time she contracted the virus, it developed into a severe case that took her life.

Battling Diseases

Maass was born on June 28, 1876 in East Orange, New Jersey to a poor German immigrant family. She entered nursing school at Christina Trefz Training School of Nurses at the Newark German Hospital when she was 17 and graduated two years later. She started working at the hospital and was made head nurse just three years later.

When the need for female nurses arose during the Spanish American War, she found her true calling. In April 1898, Maass signed up to be a contract nurse for the U.S. Army to care for wounded soldiers. She served with the Seventh U.S. Army Corps where she cared for wounded and ill soldiers in the southern United States and Cuba. She became skilled at treating diseases like malaria, typhoid, dysentery, dengue and yellow fever because more soldiers died from disease than battlefield wounds.

"Hospital at Honolulu": The photograph was taken at around the time of the Spanish American War. National Museum of Health and Medicine/CC BY 2.0

After the Spanish American War ended, Maass was discharged in 1899 only to volunteer her service again. This time, she went to the Philippines, but her duties were cut short when she was sent home after contracting dengue fever, a mosquito-transmitted disease that can cause severe joint pain.

After recovering from her illness, Maass returned to Cuba in 1900 to help Dr. William Gorgas with the U.S. Army’s Yellow Fever Commission. The commission was tasked with studying yellow fever. They had developed a theory that it was transmitted by mosquitos and not through contagion from infected people.

Gorgas and his colleague Dr. Juan Guitéras wondered if immunity could be developed from a mild case of the ailment. To test their theory, the doctors offered $100 to human volunteers willing to be infected with yellow fever.

Maass quickly volunteered. If she infected herself with yellow fever, she would understand the disease better and the experience would enable her to provide better care for her patients. She first contracted the disease by being placed in a “room full of mosquitoes” and patients suffering from a mild form of the disease. She came down with a mild case of yellow fever and survived.

The doctors wondered if Maass was immune. But, they worried that since it was only a mild case, it might not make her body immune to more severe cases. To find out for sure, Maass volunteered to infect herself again on Aug. 14, 1901. She was exposed to mosquitos that had been feeding off people with severe cases of yellow fever.

On Aug. 18, she became seriously ill. The first exposure to the virus didn’t make her immune. She succumbed to her illness and passed away on Aug. 24, 1901, at the age of 25.

Medical Legacy

After Maas’s story was published on the front page of The New York Times, readers became outraged. Her death ended experiments on humans. Further research led to a yellow fever vaccine being developed in 1937.

After Maass’s death, she was given a military funeral and buried in Cuba. But six months later, her body was relocated to her home in New Jersey, per her family’s request. In 1952, in honor of her memory, the hospital where Maass trained as a nurse was renamed the Clara Maass Memorial Hospital. It’s now known as Clara Maass Medical Center.

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