Looking back at Typhoid Mary 100 years later

Typhoid Mary Mallon is one of the best known personalities in the popular history of medicine, the cook who was a healthy carrier of typhoid fever, who spread illness, death, and tragedy among the families she served with her cooking, and whose case alerted public health administrations across the world to this mechanism of disease transmission. Alongside John Snow and the Broad Street Pump, Mary and her germ are iconic figures in the history of diarrhoeal diseases, the bright side and the dark side, but both in their own way communicators of important lessons in public health and disease transmission.

Typhoid was a big killer in nineteenth century cities, and as an indigenous disease the world over wrought a quiet and continuous devastation that may have matched or even outstripped the more blatant global eruptions of cholera. It remained a problem in many places, including North America, until well into the twentieth century, and counted some famous victims. Virginia Woolf’s brother Thoby Stephen caught it in Greece, and died in 1906; the novelist Arnold Bennett succumbed after incautiously drinking tap water in Paris in 1931. Today, however, it is still a killer in developed countries, and remains a very real hazard in regions where drinking water supplies are subject to contamination, and where personal hygiene is poorly understood. Food and water may act as the vehicles of infection, but the source is always the excreta, either or both urine and faeces, of another human being, a sufferer or a survivor, a healthy carrier.

Yet typhoid is only the spearhead of a much larger problem. Diarrhoeal diseases still cause much human misery and death across the planet, and represent a serious economic problem everywhere. One of the major perpetrators of this is the typhoid family, typhoid’s lesser cousins, the Salmonella family, some 2,500 of them and counting. While typhoid itself seems to be exclusive to humans, its cousins can inhabit both human and animal guts, can survive in contaminated environments for considerable periods of time, and can travel the world on and in contaminated foodstuffs from lettuce, and seeded sprouts to tomatoes, melons, meat, fish, poultry, and other more unlikely seeming sources like raw milk and cheese. Like typhoid itself, these Salmonella can create carriers and they infect a wide range of creatures, from humans and domestic poultry and livestock, to rodents and reptiles. Salmonella Sam, the pet tortoise, is far from unknown in the annals of food poisoning. Most humans do not call in a doctor when suffering from food poisoning, and a great many have no idea that they have become carriers. Unless they practice scrupulous personal hygiene they will, like Mary Mallon, almost certainly go on to infect other people. That, dear reader, could be you. Nor are Salmonella the only infections to be spread in this way. Large outbreaks of hepatitis A, for example, have been caused by contaminated frozen raspberries.

For much of the twentieth century the Salmonella were thought to be the main food poisoning organisms in Britain and Europe, while in the United States botulism predominated until the 1930s, after which staphylococcal intoxications were considered the main culprits. In the late 1970s, however, this picture began to change as new microbiological techniques came into use. Known food poisoning bacteria and viruses now include campylobacter, cryptosporidium, giardia, E.coli 0157: H7, and norovirus. The world of diarrhoeal infections is very much more complex now than it was in 1970. Antibiotic-resistant strains of Salmonella began to appear in the 1980s, and recent research conducted on multi-drug resistant Salmonella strains emerging in Africa suggests that HIV/AIDS infections and their treatments have established new ecological niches favouring the development of these Salmonella. In this twenty-first century, in which emergent new forms of terrorism, extreme sectarian violence, religious intolerance, and imperialist national ambitions are emerging at a scarifying rate, concerns over Typhoid Mary’s successors may seem on the trivial side. Yet it is worth remembering that each incidence of diarrhoeal infection is also an individual act of bioterrorism. Salmonella Typhimurium was actually used as a terrorist weapon in the United States in 1984, and the report on the incident was suppressed for fear of copycat incidents until after the Sarin attack on the Tokyo underground in 1995. In failing to wash our hands after visiting the lavatory, or before preparing food and drink for the table, we are each of us in danger of inflicting serious distress on one or more fellow human beings. Mary Mallon did not set out to become a domestic terrorist, but in refusing to acknowledge her condition when diagnosed, and in persisting to follow her profession without safeguard, she became precisely that.

Heading image: Salmonella NIAID. National Institutes of Health, United States Department of Health and Human Services. Public Domain via Wikimedia Commons.