It’s Professor Dave, let’s talk about typhoid fever.
Typhoid fever is a life-threatening illness that is usually food borne, and often associated
with international travel.
The main symptom of this disease is a sustained high fever that can be as high as 103-104
Other symptoms may include stomach pain, diarrhea or constipation, cough, weakness, or headache.
If left untreated, someone infected with typhoid fever can continue to have a fever for weeks
or months, which can cause a variety of complications.
Without treatment, about 30% of infected people will die from these complications.
Typhoid fever is very uncommon in the United States, Canada, Australia, Western Europe,
However, it’s more common in many other countries, affecting over 22 million people
About one in twenty people are asymptomatic carriers after they recover from the disease,
and are able to pass it on to others.
In fact, you may have heard of “Typhoid Mary,” a famous carrier of the typhoid bacterium
who was allegedly responsible for multiple outbreaks of typhoid fever in New York City
and Long Island between 1900 and 1907.
Her real name was Mary Mallon, born in Ireland in 1869.
Mary was a cook, and due to improper handwashing, as well as lack of knowledge about the disease,
51 typhoid cases and 3 deaths were directly attributed to her, even though she herself
was immune to the bacteria.
Typhoid fever is caused by Salmonella serotype typhi, which is a member of the Enterobacteriaceae
To give you some context, the Enterobacteriaceae family is the largest, and also the most heterogeneous,
collection of medically important gram-negative rods.
These bacteria are typically found in water, vegetation, soil, or intestinal flora.
In short, they’re everywhere.
Salmonella species are gram-negative.
They have flagella that help them move around.
And they are facultatively anaerobic, which means they can adapt whether oxygen is present
in their environment or not.
Salmonella typhi is always associated with disease, in contrast to opportunistic pathogens
like E. coli or Klebsiella pneumoniae.
Let’s talk about how these bacteria cause damage.
For the most part, S. typhi is spread from person to person via the fecal-oral route.
This means that most infected individuals ingest the bacteria from contaminated food
or water, and like many food borne illnesses, lack of proper handwashing is often to blame.
Once ingested, S. typhi can survive passage through the stomach, thanks to their acid
After surviving the acidic pH of the stomach, they pass through to the small and large intestines.
There, they invade the mucous membrane of the intestines, specifically the epithelial
Invasion of the epithelial cells triggers an inflammatory response, causing tissue damage
The bacteria can also spread to the liver, spleen, and bone marrow, causing systemic
The only way to know for sure if someone has been infected with S. Typhi is to test a blood
or stool sample in the lab.
For the most part, symptoms of typhoid fever begin after an incubation period of 10 to
CDC recommends that anyone with a fever higher than 102 degrees Fahrenheit should see a doctor
Once diagnosed, typhoid fever is treated with antibiotics.
For some patients, symptoms may go away just after they start taking the antibiotics, but
it’s incredibly important that they finish the full course of treatment.
That’s because the danger of typhoid fever doesn’t end when the symptoms go away, patients
can pass the bacteria to other people, or they might develop antibiotic resistance that
will make a future infection more difficult to treat.
When traveling, especially to regions of the world that are high-risk for typhoid fever,
CDC recommends getting vaccinated before leaving, and being extremely careful about what you
eat and drink.
For instance, boiling water before drinking, avoiding ice in drinks, eating only thoroughly
cooked foods, and avoiding raw vegetables that can’t be peeled.
Those are the basics regarding typhoid fever.