By the time of her death nearly 75 years ago, Irish immigrant Mary Mallon had spent 26 years living under quarantine at Riverside Hospital on an island in New York City’s East River. And to the end, Typhoid Mary—as Mallon was nicknamed by the press—refused to acknowledge her role in the spread of typhoid fever, because she had never suffered from the disease herself.

Sanitary engineer George Soper was the first to pinpoint Mallon as the link between several typhoid fever outbreaks from 1900 to 1907 in well-to-do households in the city and on Long Island—an anomaly, given that the disease was typically associated with the poor. A cook who had worked in at least six homes, Mallon had left sickness—and at least one death—in her wake.

Unable to comprehend the concept of a healthy carrier of disease, and likely bristling at Soper’s classist overtones, Mallon denied responsibility and refused to be tested. To protect the public, Soper persuaded the health commissioner to force Mallon into the hospital, where tests proved that she was indeed a carrier of typhoid bacteria.

Fearing an epidemic, the city detained Mallon at Riverside Hospital for more than two years. Despite filing suit for her freedom, Mallon remained there until 1910, when a sympathetic health commissioner finally released her with the mandate to stay away from cooking.

Then, in 1915, typhoid fever in a maternity hospital sickened 25 staff members, two of whom died. Soper, called in to investigate, entered the hospital kitchen to find none other than Mallon. This offense labeled Mallon a true threat to society, and she was sent back into quarantine.

Barron Lerner, a professor of medicine and public health at New York University School of Medicine, says Typhoid Mary’s saga raises the question of when, and to what degree public health officials have a right to restrict people who might harm others. When Cuba quarantined HIV/AIDS patients in the late 1980s, for example, many U.S. public health officials deemed the practice unacceptable. But when avian flu posed a threat to the United States in 2005, quarantining was considered a viable course of action. No matter how careful officials are, it’s difficult to keep vectors of disease from being stigmatized. “You must be as creative as you can to come up with alternative solutions before you lock someone up,” Lerner says.