A new virus which first appeared in a food market in China has crossed the world in a couple of months and declared a pandemic by the World Health Organisation As of 11th March there have been 118 619 confirmed cases of this virus, called COVID-19, worldwide, with 456 in the United Kingdom. Six people in the UK have died. Of those cases in the UK four were all linked to one other infected person who also infected another six, five in France and one in Spain. This is the story of a modern super-spreader and his Victorian era counterpart, ‘Typhoid’ Mary Mallon.
Steve Walsh Pic: Servomex
The case of our modern super-spreader Steve Walsh has been well covered in the media since he reported himself to health authorities. The 53 year old works for the gas analysis company Servomex. From 20th to 22nd January 2020 he attended a work conference in Singapore, one of 94 delegates travelling from overseas to the 109 strong body. One attendee was from Wuhan, China the centre of the epidemic. During the conference Walsh was exposed to COVID-19. Following the conference he joined his family for a holiday at Les Contamines-Montjoie near Mont Blanc in the French Alps from 24th to 28th January, staying in a ski chalet. Still feeling well he travelled on a busy easyJet flight from Geneva to Gatwick and went to a local pub, The Grenadier in Hove, on the 1st February. It was only after conference organisers alerted attendees that one of their number had tested positive for COVID-19 that Walsh alerted the authorities and was himself tested. By this time five Britons who had stayed in the same chalet became ill in France, another Brit returned to their house in Mallorca and fell ill and another group of four people flew home to the UK from the same ski resort and became unwell. All tested positive for COVID-19. All had had contact with Walsh. In the two week incubation period and without feeling unwell Walsh had inadvertently infected 10 people. After a mild illness in quarantine at the specialist infectious diseases unit at Guy’s and St Thomas’ NHS Foundation Trust in London he was discharged on 12th February.
A super-spreader is an individual who is more likely to spread a disease compared to other people with the same infection. The principle which is often used is the ‘20-80’ rule; 20% of people are behind 80% of transmissions. There are many different reasons why one person may be more contagious than others: vaccination rates, the environment, co-infections (men infected with HIV are more contagious if they also are infected with syphilis compared to those infected with HIV alone) and their viral load. A super-spreader may also be a carrier, completely symptom free, who yet can pass a disease onto others. Perhaps the most famous example of this kind of super-spreader was ‘Typhoid’ Mary Mallon.
Mary Mallon was born on September 23, 1869 in Cookstown, County Tyrone in what is now Northern Ireland. By 1884 she had moved to America to live with her aunt and uncle and to seek work as a cook for wealthy families. Between 1900 and 1907 she worked for seven families in the New York City area.
Mary Mallon in quarantine Creative Commons
A strange pattern emerged. Wherever Mary worked there was an outbreak of typhoid fever. This disease is caused by a type of Salmonella bacterium called Samonella typhi and spread in contaminated food and drink. Infected patients develop fever, abdominal and joint pains and vomiting and diarrhea. Some patients develop a rash.
This was very unusual. Typhoid fever was traditionally seen in slum areas and the poverty stricken, not the affluent houses Mary worked at. In 1900, she moved to work in Mamaroneck, New York. Within a fortnight of her arrival residents fell ill with typhoid fever. The same thing happened in 1901 when she moved to Manhattan. The laundress at the house she worked at died of the disease. She then was employed by a lawyer and again left after seven of the eight people in the house fell ill.
In 1906 she moved to the very well to do area of Oyster Bay in Long Island. At the first house she worked at ten out of the eleven family members living there were hospitalised with typhoid fever. The same thing happened at another three households. Mary continued to change jobs after each outbreak.
She was eventually employed by a wealthy banker, Charles Henry Warren, as a cook. In 1906 when the family summered in Oyster Bay Mary joined them. From August 27 to September 3, six of the 11 people in the family came down with typhoid fever. George Thompson, the man whose house they had holidayed in, was concerned that the water supply might be contaminated and cause further outbreaks. He secured the services of a sanitation engineer George Soper who had investigated similar cases.
Soper published the findings of his research in the Journal of the American Medical Association on June 15th, 1907:
“It was found that the family changed cooks on August 4. This was about three weeks before the typhoid epidemic broke out. The new cook, Mallon, remained in the family only a short time and left about three weeks after the outbreak occurred. Mallon was described as an Irish woman about 40 years of age, tall, heavy, single. She seemed to be in perfect health.”
Soper could link 22 cases and one death to this Irish cook who seemed to vanish after each outbreak. So began a chase similar to that in the movie ‘Catch Me if you Can’; as Soper tried to track down Mary Mallon. When he eventually found her and asked for samples of her faeces and urine she violently refused:
“She seized a carving fork and advanced in my direction. I passed rapidly down the long narrow hall, through the tall iron gate, and so to the sidewalk. I felt rather lucky to escape.”
On another encounter in a hospital where Mary was being treated she locked herself in a toilet and refused to open the door until Soper left. She refused to accept she was the cause of the outbreaks and that she couldn’t work as a cook.
Soper passed the case over to physician Sara Josephine Baker with whom Mary still refused to engage. In the end Baker had to enlist the help of the New York police who arrested Mary. Stool samples confirmed the presence of Salmonella typhi. In 1908 the Journal of the American Association had dubbed Mallon ‘Typhoid Mary’.
Mary was held in isolation for three years of quarantine. By 1910 she was was released having signed an affidavit that she would no longer work as a cook and take all precautions to prevent infecting others. She began to find work as a laundress a position with less job security and lower income. Having struggled to make ends meet she changed her name to Mary Brown and began to work as a cook again. Typhoid once again followed her.
In 1915 she caused an outbreak at Sloane Hospital for Women in New York City infecting 25 of whom 3 died. As before she left her position following the outbreak but authorities found her visiting a friend and arrested her again. This time there would be no second chance and Mary Mallon spent the rest of her life in quarantine. She worked at the hospital she was confined to cleaning bottles in the laboratory. In 1932 she was paralysed by a stroke. She died of pneumonia on November 11, 1938 aged 69.
At post mortem Salmonella typhia bacteria were found in her gallbladder. She had remained a carrier until her death. We now know that 1 in 20 patients with typhoid fever who are not treated will become carriers. They themselves feel well even though the bacteria lives in their faeces and urine and can be spread by poorly washed hands. This is probably what happened to Mary Mallon.
Thanks to her aliases and avoiding authorities Mary Mallon may well have caused up to 50 deaths due to typhoid fever.
Mary Mallon and Steve Walsh both show the impact one part of the infection chain can have. However, that’s as far as the similarities go. Mary knew she was contagious and yet continued to work and put people at risk and did all she could to avoid detection. Yes it’s easy for me to criticise a woman who lived a century ago without job security who feared losing her livelihood. Whatever her reasons as a result of her actions people died. Walsh didn’t know he was infected and made himself known to and co-operated with the authorities as soon as he thought he might be. They both illustrate the same key importance of the public health approach; of contact tracing and identifying sources to break the chain of infection. They also show the value of an individual’s attitude. If we think we might be at risk of passing an infectious disease on we all have to make the choice. Are we going to be like Mary Mallon or Steve Walsh?
Thanks for reading
- Jamie