Irish Women Famous in Science

. . . is not the same thing at all at all as Famous Female Irish Scientist. Mary Mallon was born in Cookstown, Co. Tyrone in 1869.  Along with a lot of other Irish people she emigrated to the United States, so that she could earn an honest dollar. The problem was that she chose to work as a cook, mainly in private households in New York while having the misfortune to be an asymptomatic carrier of Salmonella typhi the cause of typhoid fever. If her carrier-status was a misfortune for Miss Mallon, it was bloody diarrhoea and death for a number of the people for whom she worked.  S.typhi is an enteric bacterial 'serovar' (variety) closely related to the Salmonella which we worry about in home-made mayonnaise, and a little less closely related to the E.coli that we worry about in pop-concert burgers and dodgy spring-rolls.  

 In 1906, a bacteriologist called George Soper eliminated the usual sources of typhoid (the water, the drains) in one house where an outbreak had occurred.  He then hunted down some data from other sporadic cases and analysed them until he found a common factor in Mary Mallon who had worn her voluminous white apron and made brown Windsor soup for least eight other infected households.  When she was confronted with the data, she indignantly refused to accept an iota of blame as she had never had a day's illness in her life. Nevertheless, Soper published his findings in JAMA in June 1907.  On foot of that and further investigation (stool, urine and blood samples) Mallon was forcibly taken into quarantine. It was a tabloid jamboree and she is known to us even two generations later as Typhoid Mary.

A couple of years later, the NY Commissioner for Health decided that it was unethical to effectively incarcerate people who had committed no crime.  So Mallon was let go back to the outside world on the promise that she'd wash her hands more often and seek different employment. In those days before PPSN and SS numbers and gmail reading our e-mails for us, it was easy to disappear and Mary Mallon was soon fed up with being a laundress.  So she changed her name and spent the next five years cooking and infecting. After causing another serious outbreak in a NY hospital she was banged up for good. She died 75 years ago today having been quarantined for the last 23 years of her life on North Brother Island NY, an 8 hectare speck in the East River between the Bronx and Queens.

A study led by Denise Monack of Stanford University published earlier this year has found out how Salmonella evades the immune system in cases such as Mary Mallon. A similar trick is used by Mycobacterium tuberculosis, which causes, ahem, tuberculosis. Knowing the details of their evasion strategies is the first step to making drugs or effective therapies against these killer microbes.  The original paper is fascinating but sciencey: there's an executive summary in the HuffPost.