Typhoid Mary: The Most Dangerous Woman In America

"Woman Cook a Walking Typhoid Fever Factory," said the headline in a New York City newspaper in 1907. The woman was Mary Mallon, an Irish immigrant who as "Typhoid Mary" would become a notorious symbol of a public health menace.

Mary Mallon's ordeal took place at a time when the new science of bacteriology was shaping public health policies in America for the first time, and her case continues to hold lessons amid today's heightened concerns about communicable diseases.

The story, which unfolds like a detective novel, opens with a mysterious cluster of typhoid fever cases in August 1906 in a very unlikely setting: a summer house in wealthy Oyster Bay, Long Island.

Typhoid fever is a bacterial disease spread by poor sanitation. At the turn of the twentieth century, it was associated with slums and poverty. About 10 percent of those infected died.

Alarmed, the owner of the house hired civil engineer George Soper to track down the source of the infection. Soper ruled out the water supply and local shellfish, and began to focus on the new cook, Mary Mallon, who had arrived in the house shortly before the epidemic broke out.

She had since left, but Soper traced her employment history and learned that typhoid outbreaks followed her wherever she went. After Soper located Mallon, his repeated attempts to get her to submit to testing were met with the same response: a brandished meat fork and threats.

It took health department worker Dr. Josephine Baker and five police officers to apprehend Mallon.

After typhoid bacilli were found in her feces, she was sent to a quarantine island in New York's East River. But the case was far from open and shut, says Leavitt. "We see it today, certainly with multi-drug resistant tuberculosis, with HIV-AIDS, now with SARS; you see where individuals are quarantined, isolated, whose liberty is taken away in the name of protecting the public health. Mary Mallon gives us an example of that at an extreme level, because she was healthy. She wasn't even sick."

Mallon was what's known as a healthy carrier-a person who is contagious but has no symptoms. She had probably come down with a mild, undetected case of typhoid fever in 1900 and had retained active germs ever since.

While preparing food, she shed bacteria from her hands, and it never occurred to her that she was spreading disease. When her condition was explained to her, she refused to believe it and fought back by secretly hiring a private laboratory, whose results reportedly showed that she was free from infection.

Nonetheless, her tests in quarantine continued to show typhoid bacteria, and she was detained until 1910, when authorities released her on condition that she not work in food handling and that she check in regularly with health officials.

Mallon returned to freedom. But that was not the last the public would hear of "Typhoid Mary," who would turn up again in circumstances that shocked even those who sympathized with her plight.