So, before the signs and symptoms develop,
there is typically about
5-10 day incubation period,
and sometimes up to 3 weeks
before the symptoms show.
Once the symptoms show,
they'll show up in 3 phases.
The first phase is the catarrhal phase.
This phase may mimic a cold.
These patients have very mild symptoms.
They may have a low-grade fever,
a normal cough, a runny nose,
inflamed red eyes, and excessive tearing.
This is the really wet phase.
They go through a lot of
Kleenex in this phase.
The cough in this phase is
just intermittent and mild.
Next, the patient will start the second
phase, and this is the paroxysmal phase.
This is where the cough
becomes way more intense,
and there can be an inspiratory whoop
sound, followed by post-tussive vomiting,
meaning the patient will cough
to the point of vomiting.
The coughing fits, or paroxysms, increase
in frequency and occur more at night.
And sometimes, the patients will say the
cough just takes their breath away.
The duration of this
phase is highly variable,
and typically lasts for 1-10 weeks.
Next, is the third phase, or the
convalescent phase, and this is the end.
This is when it's wrapping up.
It lasts 1 to 2 weeks, and here,
your patient will gradually improve
and have a reduction in their symptoms.
Here, you can see the typical
clinical course timeline.
Although there is significant
variation among patients,
this is the standard course.
Their paroxysmal stage can last
anywhere between 1 and 6 weeks.
So, let's start over on the left.
First, is the incubation period.
This is where the patient has been
exposed to somebody who has pertussis,
but they don't have any symptoms yet.
This is typically 5-10 days,
but can be up to 21 days.
Then the patient will start with symptoms,
and they start in phase 1
which is the catarrhal stage.
This typically lasts 1-2 weeks.
And remember, this looks like a cold.
The patient has a runny nose, maybe a
low-grade fever, just a mild, normal cough.
And the problem with this is this is
when the patient is very contagious.
They may be going to work
and may be going to school
thinking they only have a cold,
and they are spreading
the pertussis droplets
in a 6-foot distance around
them and on to surfaces.
Next, they will progress
to the paroxysmal stage,
and this is where their cough
They will be up at night with coughing fits,
they may cough to the point of vomiting,
and they will feel like their breath
is being taken away by their cough.
Now, the third stage, again,
is the convalescence stage,
and this is when the
patient begins to improve.
So, in patients with uncomplicated pertussis,
the physical exam findings
contribute little to the diagnosis.
And most patients with
pertussis don't have a fever.
They may have a low-grade
fever in that phase 1 stage,
but the rest of the illness,
they should be afebrile.
Now, in very young patients, the
patient may present with apnea only.
They may not have a cough.
They may not make the whooping sound,
and they may not have
the classic catarrhal stage
that you're looking for with the runny
nose and the cold-like symptoms.
These patients may just have periods of
apnea, where they aren't able to breath,
and this is because of the spasms
happening in their airway
and with their diaphragm
because of pertussis.
The lung sounds are usually clear on exam.
The patient may have a whooping
sound with their cough.
However, it depends on the
size of the airway diameter.
Adults do not usually make
the inspiratory whoop.
It's typically something
with pediatric patients.
The patient may have cyanosis present
due to their intense coughing fits
because they are actually getting hypoxic
while they're having these
massive coughing fits.
And they may cough to
the point of throwing up.
This is that post-tussive vomiting.
Now, the coughing is intense with pertussis.
Patients will pull muscles in their back,
they will have sore abdominal muscles,
and they can even have sub-conjunctival
hemorrhages in their eyes from coughing.
How do we diagnose pertussis?
Well, clinicians commonly use
several types of lab tests
to diagnose Bordetella pertussis.
It's very useful because there's
a lot of respiratory pathogens
that have similar clinical symptoms,
and it's really important to diagnose
pertussis from a public health perspective.
So, the Gold Standard is a culture.
This is the most specific method for
identification, but other methods,
such as the PCR or a blood
test, are other options.
A culture is most useful in the first
2 weeks after the onset of the cough.
So, a PCR test is useful because
it gives rapid results,
and it has excellent sensitivity.
However, it varies in specificity.
So, you should obtain a culture
confirmation in a pertussis patient
or a suspected patient with
pertussis during an outbreak.
A PCR test is useful from 0-3
weeks after the onset of cough,
and sometimes, up to 4 weeks.
But after the fourth week of the cough, the
bacterial DNA wanes in the nasopharynx,
and you might not be able
to detect it with a swab.
This will give you a false negative.
So cultures and PCRs are obtained by
inserting a swab into the nasopharynx.
This is an unpleasant
procedure for the patient,
and it's also an unpleasant
procedure for the clinician.
Children will need to be
restrained during this procedure.
If able, they will blow their nose,
and then the clinician will advance the
swab into the postural nasopharynx,
which is pretty far.
And sometimes, both nares need to
be tested depending on the test.