Clara Maass (1876–1901), Nurse Martyr in the Battle Against Yellow Fever

At the turn of the last century, the fact that yellow fever was spread by mosquitos was still a theory. A human study conducted in Cuba by Johns Hopkins physician Jesse Lazear, M.D., produced inconclusive results until Lazear himself died after being bitten by an infected mosquito.

In late 1900, Lazear’s supervisor, Maj. Walter Reed, M.D., traveled to Cuba to oversee the next phase of the study. By early 1901, the focus of Reed’s experiments had shifted from confirming the link between mosquitos and yellow fever to inoculating patients in hopes of immunizing them against the disease. Reed’s staff began recruiting additional volunteers, including American servicemen and a number of Spanish immigrants.

The Seventh Bite

Clara Maass had arrived in Cuba shortly before Reed, answering a call for nurse volunteers. Because of her previous work with yellow fever victims, she soon became involved with the experimental work, which was conducted at Las Animas Hospital in Havana.

In May, she volunteered for Reed’s experiments,  allowing herself to be bitten by mosquitos infected with yellow fever. Each of the volunteers was paid $100 in gold — a lot of money back then — but she didn’t do it for financial gain. (She sent the money home to her mother.) Maass was drawn to the study because of the deadly toll she had seen the disease take on the soldiers and civilians she’d cared for. She was the only woman among the 19 volunteers.

Why would she participate in this dangerous effort? She must have known the high stakes. Perhaps she believed that having been exposed to afflicted patients had fortified her immune system against the disease or that her youth and strength would give her an advantage should she become ill. Undoubtedly, she believed that if she perished, it would be worth it for the sake of medical progress.

Between May and June, Maass was bitten by infected mosquitos six times. In June, she developed a very mild case of yellow fever. Because the doctors weren’t sure this was enough to immunize her against the disease, she consented to be bitten a seventh time, on Aug. 14, 1901. This time, Maass was not so lucky. Four days after this last bite, she developed severe yellow fever. She died six days later, only 25 years old.

A Lasting Legacy

Maass’s death brought an end to Reed’s human experiments, but her sacrifice was not in vain. There was no longer any doubt that mosquitos could transmit the disease, which meant that public health officials could reduce yellow fever outbreaks through mosquito control measures.

The deadly experiments also demonstrated that trying to inoculate patients using the full-strength virus was much too dangerous. Work continued on alternatives, eventually leading to the development of a viable yellow fever vaccine in 1936.

The vaccine, which is now considered an “essential medicine” by the World Health Organization, uses an attenuated (weakened) live virus to provide lifelong immunity with far less risk.

Fifty-one years after Maass’s death, the Newark hospital where she trained and worked was renamed the Clara Maass Memorial Hospital (now called Clara Maass Medical Center) in her honor.

Maass once eloquently declared, “We nurse people, not diseases.” She saw that her patients were in need of nursing care and she stepped up to provide it, even at great personal risk. She would no doubt be proud to see the way nurses are continuing to step up and care for patients amid a deadly global pandemic.

Like Maass, nurses today don’t always know everything about the conditions our patients suffer, but we do know that we’ll be by their sides when they need us most.

JESSICA DZUBAK, RN, MSN, is the director of nursing practice for the Ohio Nurses Association and a freelance writer specializing in the healthcare industry.

In this Article: Historical Nurses, Medical Research, Yellow Fever