My gal Sal and Typhoid Mary

Wee Beasties

“Mary has died of Typhoid Fever”. Ah, yes. If you are of a certain generation, you remember being met with these abrupt notifications while playing Oregon Trail. While this game taught generations of young people about Western migration in 19th-century America, it also familiarized them with various diseases…and, how to avoid getting run over by wagon wheels.

This month, our hosts are exploring the root of the cause – diving into species and subspecies of Salmonella.

More about Salmonella:

CDC’s summary of Salmonella

Salmonella Nomenclature

Mary Mallon (1869-1938) and the history of typhoid fever

Stay tuned for more episodes, posting on the first Thursday of each month. Subscribe to our show wherever you get your podcasts and find more info at weebeastiespodcast.com   

The Wee Beasties podcast is a production of Nephros, Inc., a company committed to improving the human relationship with water through leading, accessible technology.

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SHOW TRANSCRIPT:

Christian: I am back with Dr. Kimothy Smith. Kimothy, welcome back!

Kimothy: Thanks, Christian. What’s new?

Christian: Well, I’ve been combing through the annals of gastroenterology in search of the origin of “Typhoid Mary” and learned a few things I’d like to share.

Kimothy: By all means. What ya got?

Christian: Alright, so check it out, in case you’re not current on your NYC history or your only reference for Typhoid fever was that Oregon Trail game back in the late ’80s…and this is literally from the Annals of Gastroenterology…I’ll throw a link in the show notes – Typhoid Mary was the name eventually given to a woman named, Mary Mallon who lived in NYC in the early 1900s and became notorious as a healthy carrier of Salmonella thypi – the bacterium that causes Typhoid fever. She was an immigrant, not necessarily well off, and was employed as a cook for wealthy families. Now, this was before a vaccine was available and before antibiotics. An investigation had started because there were many people getting sick with a fever, and the investigator trying to track down the source noticed there were pockets of families employing the same cook. Mary was leaving after the infection had occurred to move on to a new family to cook for them. In the end, there were 122 people infected, 5 dead. And that year over 3,000 people in NYC had become infected in 1907 – she was apparently the source.

What’s interesting is that there was no tracking mechanism in place, so investigations had to be done just by a small group or single man. There was an assumption that a microorganism was suspected of being responsible, but nobody knew why. The investigation really corroborated that hypothesis which eventually came from a team of veterinary scientists. So, in 1880, this guy Daniel Elmer Salmon ended up naming Salmonella typhi as a consequence of this investigation.

Kimothy: Sticking with your history bend for a minute, this is not so long after the cholera plague in London. Germ theory was still a controversial thing, they thought it was neighbors. So, go vets! Real doctors treat more than one species.

Kimothy: So, if you haven’t inferred already, we’re going to give you a snapshot of Salmonella today. Salmonella enterica, specifically.

Christian: Yeah, so…a query sir. As I was sifting through literature, I didn’t see a lot of mention of enterica early in the investigation of Typhoid fever. Can you summarize how Salmonella enterica became the catch-all for all the varieties of Salmonella?

Kimothy: Yeah, it’s a bit unusual because as you said, Christian, the initial outbreak investigation resulted in named in Salmonella typhi and now we have Salmonella enterica.

It’s important to remember that science naming conventions are like kaleidoscopes – the contents remain the same, but the picture and how it’s described change depending on who’s holding the instrument. Such has been the reshuffling with Salmonella. Most of the scientific community now breaks Salmonella into two species Salmonella bongori and Salmonella enterica into 6 subspecies and over 2600 serotypes. But essentially it comes down to two groups – Salmonella that causes gastroenteritis and then those that cause enteric fevers.

Christian: Which patient populations are most at risk for acquiring Salmonella?

Kimothy: The CDC estimated that Salmonella causes 1.2 million illnesses and 450 deaths annually in the US. Anyone can become infected with the bacteria – fecal-oral and food & water are the most common routes. The populations at greatest risk are typical demographic we’ve discussed for all our opportunistic pathogens – those under the age of 5 and over the age of 65, and those with weakened immune systems.

Christian: And how does it present?

Kimothy: So, the gastrointestinal infection that results when you ingest the bacteria is Salmonellosis, and it presents exactly how you would expect for a pathogen that survives in your GI tract – fever, abdominal cramps, and diarrhea. Symptoms manifest within about 12-72 hours and typically last about a week. You can take antibiotics, but most people will be able to recover without pharmaceutical intervention. Typhoid fever is, as you might expect, slightly different. Patients become symptomatic gradually and once a fever presents it is accompanied by extreme fatigue, usually a skin rash or skin discoloration, headaches, abdominal pain, and constipation. Without medical intervention, the fever can be fatal. But it can easily be treated with antibiotics, such as azithromycin.

Christian: And if you really believe in preventative medicine folks, you can always get the vaccine. Also, Typhoid fever shouldn’t be confused be typhus, right? Two totally different pathologies. Typhus is caused by Rickettsia, a different gram-negative bacterium that spreads itself around to humans hitching a ride on lice and fleas. I digress. Tell me about Cell morphology and other unique descriptions associated with Salmonella.

Kimothy: Gram-negative rods, motile with flagella, about 0.4 - 0.7 micron in size.

Christian: Quick question before I let you go: do both varieties of Salmonella transmit the same?

Kimothy: So, good question. No, they do not. The variety that causes Typhoid fever is spread from human to human only and the variety that results in gastroenteritis is transmitted in food or water.

Christian: Copy that, so we’re in the clear for acquiring Typhoid fever a la hospital drinking fountains. Kimothy, as always, thanks so much for the chat today.

Kimothy: You bet, Christian.