Typhoid Fever: Pathogenesis (vectors, bacteria), Symptoms, Diagnosis, Treatment, Vaccine
Summary
TLDRThis video discusses typhoid fever, its causes, transmission, symptoms, diagnosis, and treatment. Typhoid fever is caused by the bacteria *Salmonella enterica* serovar typhi or paratyphi and is transmitted through contaminated food or water, especially in areas with poor sanitation. Symptoms include fever, abdominal pain, and rose spots. Diagnosis is based on exposure history and symptoms, confirmed through tests like blood and stool cultures. Treatment involves antibiotics, though resistance patterns vary. Prevention focuses on sanitation, hygiene, and vaccination. The video also covers chronic carriage and relapse in some cases.
Takeaways
- 🦠 Typhoid fever is caused by Salmonella enterica serovar Typhi or Salmonella Paratyphi, with slight variations in clinical presentation, collectively known as enteric fever.
- 🤒 Typhoid fever is transmitted between humans via direct or indirect contact, often through contaminated food or water. Children, young adults, overcrowding, and poor sanitation increase the risk.
- 🧬 The bacteria survive gastric acids, penetrate the intestinal lining, and spread through lymphoid tissue, entering the bloodstream to cause systemic symptoms.
- 🌡️ Symptoms appear 5 to 21 days after ingestion, beginning with a 'stepwise' fever in the first week, followed by abdominal pain and rose spots in the second week, and potentially intestinal bleeding and splenomegaly in the third week.
- 🩺 Diagnosis of typhoid fever is based on clinical suspicion, especially after exposure to endemic areas. Blood and stool cultures can confirm the diagnosis, though sometimes empiric diagnosis is used.
- 💊 Treatment includes antibiotics like fluoroquinolones, azithromycin, and ceftriaxone. Treatment may vary based on local resistance patterns, with multi-drug-resistant strains being a concern.
- 🔄 Relapse can occur 2 to 3 weeks after resolution, with symptoms reappearing depending on the antibiotic used and local resistance patterns.
- 👩⚕️ Chronic carriage happens in 1-5% of cases, especially in adult women or those with biliary diseases. Carriers can excrete the bacteria for over 12 months, with gallstones acting as bacterial reservoirs.
- 💧 Prevention of typhoid fever includes access to clean water, proper sanitation, hygiene practices, and vaccination.
- 📚 Historical reference to 'Typhoid Mary' highlights the importance of identifying chronic carriers who can spread the disease without showing symptoms.
Q & A
What causes typhoid fever?
-Typhoid fever is caused by an infection with a gram-negative bacterium called *Salmonella enterica* serovar Typhi, or related bacteria like *Salmonella paratyphi*, which has subtypes A, B, and C. These bacteria lead to different clinical presentations, but they all cause typhoid fever.
How is typhoid fever transmitted?
-Typhoid fever is transmitted from human to human, either through direct contact or indirectly via contaminated food or water. Poor sanitation and overcrowding are risk factors that facilitate the transmission.
What are the main risk factors for contracting typhoid fever?
-The main risk factors include being a child or young adult, overcrowding, and poor sanitation. These conditions increase the likelihood of direct or indirect contact with contaminated food or water.
How do Salmonella Typhi and Paratyphi bacteria infect humans?
-These bacteria are ingested orally, survive stomach acids, and enter the duodenum. They penetrate the intestinal epithelium and invade lymphoid tissue through mechanisms like entering via M cells or using the CFTR chloride ion channel.
Why might patients with cystic fibrosis be less susceptible to typhoid fever?
-Cystic fibrosis patients may be less susceptible because the bacteria use the cystic fibrosis transmembrane conductance regulator (CFTR) channel to enter cells. In cystic fibrosis patients, this channel is mutated, potentially preventing the bacteria from hijacking it to infect the intestines.
What are the early symptoms of typhoid fever?
-The early symptoms include a stepwise fever, which shows a gradual increase in temperature over time. This occurs in the first week of infection, along with general discomfort.
What are rose spots, and when do they appear during typhoid fever?
-Rose spots are small, blanchable papules (1-5 mm) that appear on the skin during the second week of typhoid fever. These spots are a characteristic symptom of the disease.
What are the potential complications in the third week of typhoid fever?
-In the third week, complications include intestinal bleeding, hepatosplenomegaly (enlargement of the liver and spleen), and intestinal perforation. These are serious symptoms that require medical attention.
How is typhoid fever diagnosed?
-Typhoid fever is diagnosed by suspecting it based on symptoms such as fever, abdominal pain, and GI issues, especially if the patient has been in an endemic area. Blood and stool cultures are typically used for confirmation.
What are the common treatments for typhoid fever?
-The treatment depends on local resistance patterns but generally includes antibiotics like fluoroquinolones, azithromycin, ceftriaxone, or carbapenems. Severe cases might also require steroids like dexamethasone.
Outlines
🦠 Introduction to Typhoid Fever: Causes and Transmission
This paragraph introduces typhoid fever, describing its bacterial causes—Salmonella enterica serovar typhi and Salmonella paratyphi—and the different clinical presentations between the two. The terms 'typhoid fever' and 'enteric fever' are often used interchangeably. The bacteria are transmitted only between humans, either through direct contact or via contaminated food or water. Risk factors include being a child or young adult, overcrowding, and poor sanitation.
🧬 Pathogenesis: How Typhoid Bacteria Infect the Body
This section explains the pathogenesis of typhoid fever. The bacteria are ingested, survive the stomach's acidic environment, and invade the small intestine's epithelial tissue through various mechanisms. Once inside, they proliferate in lymphatic tissue, causing Peyer's patch hypertrophy, and spread throughout the body via the lymphatic and circulatory systems, leading to further complications.
🤒 Symptoms of Typhoid Fever: Fever, Rose Spots, and GI Complications
The clinical presentation of typhoid fever is detailed here. Symptoms typically appear 5 to 21 days after infection, starting with a stepwise fever in the first week. In the second week, abdominal pain and rose spots develop. The third week brings severe complications, including intestinal bleeding, hepatosplenomegaly, and intestinal perforation. Other symptoms can include diarrhea or constipation, headaches, and typhoid encephalopathy, which affects mental status.
🧪 Diagnosis and Treatment of Typhoid Fever
Diagnosis of typhoid fever involves identifying symptoms and exposure to endemic areas. Blood and stool cultures are common diagnostic tools. Treatment depends on local bacterial resistance patterns, with antibiotics like fluoroquinolones, azithromycin, and ceftriaxone used. For severe cases, steroids such as dexamethasone may be added. There is a risk of relapse, typically two to three weeks after initial recovery, influenced by the antibiotic used.
💊 Chronic Carriage and Prevention of Typhoid Fever
Some individuals may become chronic carriers of the bacteria, continuing to excrete it even after treatment. This occurs in 1-5% of cases, particularly in adult women or those with gallbladder issues like gallstones. Chronic carriers may require gallbladder removal to fully eliminate the bacteria. Prevention focuses on sanitation, hygiene, and vaccination. Famous historical cases like 'Typhoid Mary' highlight the dangers of asymptomatic carriers.
🔔 Conclusion and Call to Action
The final paragraph encourages viewers to explore more content on infectious diseases, subscribe to the channel, and turn on notifications to stay updated. The creator thanks viewers for watching and hopes to see them in future videos.
Mindmap
Keywords
💡Typhoid Fever
💡Salmonella enterica serovar Typhi
💡Enteric Fever
💡Transmission
💡Stepwise Fever
💡Rose Spots
💡Peyer's Patches
💡Relapse
💡Chronic Carriage
💡Antibiotic Resistance
Highlights
Typhoid fever is caused by a Gram-negative bacterium, Salmonella enterica serovar Typhi, or related bacterium, Salmonella Paratyphi.
Humans are the only reservoir for typhoid fever bacteria, and it is transmitted through contaminated food or water, or direct contact.
Risk factors for contracting typhoid fever include being a child or young adult, overcrowding, and poor sanitation.
Typhoid fever bacteria survive gastric acids and invade intestinal epithelium, using CFTR chloride ion channels for entry.
Patients with cystic fibrosis may be protected from typhoid fever due to mutations in the CFTR chloride ion channel.
Once inside the body, the bacteria proliferate in the submucosa, causing Peyer's patch hypertrophy and disseminating through the lymphatic and blood systems.
The clinical presentation of typhoid fever includes stepwise fever, abdominal pain, and rose spots during the first two weeks of infection.
In the third week, symptoms worsen with intestinal bleeding, hepatosplenomegaly, and possible intestinal perforation.
Both diarrhea and constipation are equally common in typhoid fever, along with headaches, disordered sleep, and typhoid encephalopathy.
Diagnosis is based on clinical suspicion, particularly in those exposed to endemic areas, and confirmed through blood, stool, or bone marrow cultures.
Treatment depends on local resistance patterns, with first-line antibiotics including fluoroquinolones, azithromycin, ceftriaxone, or carbapenems.
Relapse occurs in some patients two to three weeks after resolution of fever, often depending on the antibiotic used.
Chronic carriers, usually adult women or those with biliary diseases, can excrete the bacteria for more than 12 months after recovery.
Prevention of typhoid fever includes ensuring clean water, sanitation, hygiene, and vaccination.
Cholecystectomy is recommended for chronic carriers as bacteria often form biofilms on gallstones in the gallbladder.
Transcripts
hey everyone this lesson is on typhoid
fever in the summer type of what causes
typhoid fever all chuckle the
pathogenesis signs and symptoms
diagnosis and treatment of typhoid fever
so typhoid fever is caused by an
infection with a gram-negative bacteria
Salmonella enterica serovar typhi or
simply seminal a type ii or a related
bacteria Salmonella parrot IV which has
different subtypes a B or C both of
these bacteria cause slightly different
clinical presentations but we generally
call infections by both of these typhoid
fever there's also the term we use
enteric fever which describes both the
typhoid paratyphoid fever so we can use
typhoid fever or enteric fever
interchangeably house typhoid fever
transmitted well humans are actually the
only reservoir for this type of bacteria
so it has to come from a human to
another human
so either can this can be through direct
contact or indirect contact via
contaminated food or water now the risk
factors for contracting typhoid fever
include being a child or young adult
children and young adults are more
susceptible to typhoid fever
another one is overcrowding so you can
imagine if there's lots of people if
anybody's infected they can easily
transmit it through direct or indirect
contact and poor sanitation is also
another risk factor so again through
contaminated food water if there's poor
sanitation with regards to food or water
it's easier to transmit this so how does
Seminole at I fee and Seminole apéritif
II infect us and make us sick to cause
typhoid fever
well these bacteria are ingested orally
and they actually survive the gastric
acids and then enter into the duodenum
which is the first part of the small
intestine when they enter the duodenum
they actually can penetrate through
intestinal epithelium and invade into
lymphoid tissue and they do so by a
couple of different mechanisms one is
through an EM cell which is part of the
mucosal associated lymphoid tissue
system or mult system and the second way
that this bacteria can actually
penetrate into the epithelium is through
direct penetration into an epithelial
cell via CFTR or cystic fibrosis
transmembrane conductance regulator
which is a chloride ion channel so may
be thinking cystic fibrosis
transmembrane conductance regulator what
does this mean well this is actually the
chloride ion channel that is mutated in
patients with cystic fibrosis so
essentially what happens is the seminal
type your parrot IP
utilize or hijack this chloride ion
channel and use it to enter into
intestinal epithelial cells so what's
very interesting is that because this
channel is mutated in patients with
cystic fibrosis cystic fibrosis patients
may actually be protected against
typhoid fewer infections or infections
by the bacteria that cause typhoid fever
so again very interesting another thing
that happens is that the seminal type II
bacteria once it penetrates into the
epithelium will actually proliferate in
the submucosa causing peyer's patch
hypertrophy peyer's patch is lymphatic
tissue in the intestines that becomes
hypertrophy because the bacteria
actually proliferate s' inside to cause
that hypertrophy and eventually the
bacteria will disseminate through the
body by the lymphatic system and
hematogenous lead through the blood to
cause many of the symptoms were talked
about in the next slide
so the clinical presentation of typhoid
fever can be summed up by a fever and
abdominal pain but more specifically
with this infection there's a symptom
onset that occurs in roughly 5 to 21
days after ingestion of the bacteria
when the symptoms occur depends on the
age of the patient the health of the
patient the gastric acidity of the
patient's stomach and the number of
organisms that are ingested in the first
week of infection we have what we call a
stepwise fever this is the first symptom
you're gonna see stepwise fever is
called that because we see a gradual
step like increase in fever so you'll
see a temperature it'll bump up to a
higher level and it will Plateau and
then it'll bump up to another higher
level and plateau at that so that's why
we call it stepwise in the second week
of infection this is when we see the
abdominal pain and we also see what we
call rose spots row spots are small
usually one to five millimeters in size
Blanche able papules so you're gonna see
these on the skin of an infected
individual there Blanche evils so that
means that if you actually push on them
they will disappear but then will
reappear so those are what we call it
rose spots and in the third week you're
gonna see some of the worsening symptoms
you're gonna see intestinal bleeding so
you might see hematochezia Molina you're
also gonna get a paddle splenomegaly so
an enlargement of the liver and the
spleen and you can also see intestinal
perforation so essentially because of
all that
proliferating bacteria within the
submucosa may actually cause an
intestinal perforation other symptoms of
typhoid fever are due to the GI system
being affected so you can see diarrhea
or constipation these seem to occur with
equal frequency so about 50% of the time
you'll have diarrhea with typhoid fever
the other 50% of the time you'll have
constipation you can also see headaches
disordered sleep patterns and you can
also get what we call typhoid
encephalopathy typhoid encephalopathy
causes an altered Mental Status
confusion delirium and even acute
psychosis so how do we make the
diagnosis and how do we treat typhoid
fever diagnosis of typhoid fever is
through usually suspecting it in the
first place so you suspect the typhoid
fever if there's exposure to an endemic
area and if you have been exposed to an
area that has a lot of typhoid fever
you're gonna suspect it even more if
there's three days or more fever and GI
symptoms like the diarrhea in the
constipation and the abdominal pain we
talked about or the hepatosplenomegaly
or the intestinal bleeding and then once
you have suspected it you can do some
tests you can do blood and stool
cultures could do a bone marrow test but
that's not gonna be something that you
are gonna do and a lot of times it can
be an empiric diagnosis you're gonna see
the symptoms you're gonna see that
they've been in an endemic area they're
not vaccinated and then you're going to
say you know what this is probably a
diagnosis of typhoid fever and the
treatment of typhoid fever depends on
local resistance pattern so in some
parts of the world you're gonna have
different strains of Salmonella typhi or
perro typing there could be multi-drug
resistance or MDR strains or even
extensively drug resistant or XDR
strains of this bacteria and that's
gonna change which antibiotic you're
gonna use generally speaking the first
line of antibiotics that you're going to
use for typhoid fever include
fluoroquinolones azithromycin
ceftriaxone or carbapenems in for severe
illness you might want to add on a
steroid like dexamethasone now other
considerations of typhoid fever include
what we call relapse so a state of
relapse generally occurs two to three
weeks after resolution of the fever so
what happens is the symptoms of typhoid
fever come back after about two to three
weeks after
having resolution of the fever so this
is what we call relapse and this risk of
relapse generally depends on the
antibiotic that you used and again with
the local resistance patterns you're
gonna want to keep an eye on which
antibiotic depending on the resistance
patterns in that area another
consideration for typhoid fever includes
what we call chronic carriage chronic
carriage is what happens when you have a
person that's had typhoid fever you
given them right antibiotic they were
treated they no longer have symptoms or
asymptomatic
and it only happens in a few rare
individuals one to five percent of
patients generally speaking and what
chronic Harwich means is that they have
been treated they're a cinematic they're
feeling better but they are still
excreting the organism even for more
than twelve months and that's generally
what we call chronic carriage so they
could be an acute carrier that gets me
still excreting the organism like the
Seminole of Taif your parrot i fee even
after being treated but when they've are
still excreting the organism even more
than twelve months after the resolution
of the acute illness we call that
chronic carriage so these people could
just have this with them for a long time
the risk factors for chronic carriage
include the following includes generally
adult women biliary tract disease like
having cholelithiasis so gall stones the
reason for this is because the seminole
of bacteria hides out in the gall
bladder so if there's any gallbladder
stones in there
they generally concede in and cause a
biofilm on those gall stones to stay
there because the seminal bacteria cause
biofilms and stay within the person's
gall bladder the only way we can get rid
of them is actually to get rid of the
gall bladder so I'll call Asustek t'me
is the treatment for chronic carriers
and another consideration for typhoid
fever is prevention of typhoid fever in
the first place and this can occur
through having fresh water sanitation
and hygiene remember a lot of times this
is transmitted from contaminated waters
and there's also a vaccination for
typhoid fever so having a vaccine for
typhoid fever and having fresh water and
sanitation and hygiene can help a lot in
preventing this in the first place
so to summarize the other considerations
of typhoid fever we need to worry about
a few things
first we need to worry about relapse so
even if we've treated a patient with
typhoid
fever we might not have picked the right
antibiotic other consideration with
typhoid fever is the state of chronic
carriage and this is again an
asymptomatic state and this is where
that person or individual will excrete
seminal Atty for your parrot IV into
their environment for extended periods
of time this is what actually happened
with typhoid mary she was a chronic
carrier she wasn't symptomatic but she
was passing and excreting this organism
and infecting many other individuals and
again the risk factors for chronic
carriage include adult women and those
with biliary tract diseases especially
cholelithiasis because gallstones act as
a source of that bacteria and again the
most important thing to take from all of
this is prevention of typhoid fever in
the first place again we want to have
fresh water sanitation and hygiene that
is critical to prevent the spread of
typhoid fever in there's a vaccination
for typhoid fever that can actually
reduce or eliminate it or help prevent
individuals from contracting typhoid
fever so if you want to learn more about
other infectious diseases please check
out my infectious disease playlist and
if you haven't already please consider
liking subscribing and clicking the
notification Bell to help support the
channel and as always think as much
watching and I hope to see you next time
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