Typhoid Mary – An Asymptomatic Tale

The story of Mary Mallon, AKA Typhoid Mary, has real relevance to today’s fight against Coronavirus, especially the dangers of assuming that, without symptoms, you can’t harm or infect others. We know that many of those with Coronavirus show no symptoms, yet retain the ability to pass the virus on to others. The fight against typhoid fever over 100 years ago included this shocking case of an asymptomatic carrier who was, literally, killing others.

Between 1900 and 1907, Mary Mallon cooked in the homes of seven wealthy families in the smarter parts of Manhattan and in every one of them people fell sick or died. Each time she slipped away and found work elsewhere. Understandably, people were shocked to discover that their households had been infected with typhoid fever, which was quite common in the slums of New York but not something that the wealthy families of Manhattan were used to seeing in their own houses.

One of the families hired a private investigator to uncover how it had been infected, and he traced the source of infection in all the households back to Mary. He eventually caught up with her and tried to get her to take a test, but she didn’t have any symptoms and refused to do so, so he reported her to the New York City Health Department.

They arrested her as a suspected public health threat and forced her to give samples. She tested positive for typhoid and admitted that she almost never washed her hands. She was subsequently quarantined but was released after three years and went on to infect hundreds more people before authorities caught up with her and quarantined her again – and she remained in isolation until the end of her life.