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Practice English Speaking&Listening with: Typhoid Fever: Salmonella typhi

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Its Professor Dave, lets 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

degrees Fahrenheit.

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,

and Japan.

However, its more common in many other countries, affecting over 22 million people

each year.

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 ofTyphoid 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, theyre 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.

Lets 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

tolerance genes.

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

and diarrhea.

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

14 days.

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

its incredibly important that they finish the full course of treatment.

Thats because the danger of typhoid fever doesnt 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 cant be peeled.

Those are the basics regarding typhoid fever.

The Description of Typhoid Fever: Salmonella typhi