What is parapertussis? It is annoying for sure, but it isn't quite as scary as it sounds.
Bordetella is a bacterium best known for whooping cough in humans
(B.pertussis) and kennel cough in dogs (B.bronchiseptica). B.
parapertussis is a lesser known member of the family. It is estimated
that 1%-35% of known Bordetella infections are caused by B.
parapertussis. Because only a small percentage of patients actually ever
get tested, these are tough statistics to get accurate. To compound the
challenge of data gathering, parapertussis is not one of the diseases
that mandates reporting it to the public health department, so it really
is tough to have a real sense of numbers.
The nastier cousin, B.Pertussis is making the rounds. Because
it is currently active at some local San Francisco schools and daycares,
several of our coughing patients have asked to be tested. A number of
those results came back negative for pertussis (fortunately), but
positive for parapertussis. The PCR test done to rule out pertussis
tests for both. (It is actually possible for folks to have both
illnesses at the same time, how unfair is that?!) Parapertussis has
some distinct differences. It is very similar to regular pertussis but
not nearly as severe or long lasting. One main difference is that
parapertussis does not produce the pertussis toxin which is responsible
for some of the more severe symptoms.
With parapertussis, patients can still have the prolonged cough,
(with characteristic coughing fits) and vomiting but we are talking
about 3 weeks instead of 3 months. This is a fairly variable illness; up
to 40% of patients with it can be almost symptom free.
Just as with Pertussis, we are more concerned about infants younger
than 6 months, or someone with an underlying health condition or
compromised immune system.
This month our patients who tested positive were all fully
vaccinated, and that makes sense. While the whooping cough vaccine gives
about 80-90 % protection against pertussis to folks who get it, it does
NOT protect against parapertussis.
Just like pertussis (and the common cold), parapertussis is transmitted from coming in contact with respiratory secretions.
The incubation period is also similar to that of pertussis.
This is measured from the time someone was exposed until they come down
with the illness. Most commonly it is 7-10 days, but it can be as short
as 5 days and you can’t really count yourself as out of the woods until
at least 21 days have past since the exposure and no symptoms have
presented.
A patient is infectious (they can spread the illness and make
someone else sick) from a day or so before showing the first symptom
until up to about 3 weeks after the beginning of the illness. If
treated, a person is still considered contagious until they have
finished a 5 day treatment.
There are not really any official guidelines for managing the
illness. Basic symptomatic treatment measures such as steam, fluids and
rest will help get you through. Certainly if the patient is less
that 6 months old, or in close contact with a young baby or someone
high risk, they should get treatment as soon as possible. The
standard treatment is five days of Azithromycin. Remember that patients
are considered contagious until they have completed the course.
For the older, lower risk patients, should we treat? The
limited studies that are out there suggest that treatment that is
initiated within the first 6 days of the onset of the symptoms may
possibly help get the patient better faster. Another benefit of early
treatment is that it can minimize the spread.
Prophylactic treatment, to prevent the disease in someone who was
exposed but isn’t sick yet, is worth considering for high risk contacts,
if started within 2-3 weeks of the exposure. Most experts agree that
starting prophylaxis more then 3 weeks after the exposure is probably of
no benefit.
But in most cases, it isn’t that simple. We don’t tend to
bother seeing patients unless they have a cough that is really
troublesome or lingering; we couldn’t possibly bring everyone in the
minute they start to cough. The other issue of course is that nobody
wants to overuse antibiotics. With pertussis and parapertussis, the
illness often starts for a week or so with a mild cold before the
coughing begins.By the time we recognize that we are dealing with
parapertussis, the reasonable window for treating may already be passed.
I do have my antenna up for any illness that has coughing
spasms. Many of these patients seem fairly well, until a coughing fit
hits. Often there will be vomiting from coughing so hard. There may or
may not be a characteristic whoop.
Here is the question many of you are asking: Can they go to
school? Officially parapertussis is considered a mild but irritating
illness. It is not a reason to keep them home. Keep in mind that people
are contagious a bit before they have flagrant symptoms, so we have to
exercise a bit of common sense here. Someone who was at school on Monday
and starts coughing on Tuesday has already exposed all of the
classmates. They also likely picked it up from a fellow student. Keeping
them home if they feel fine and have no fever makes no sense. If you
have a child who is miserable, feverish, poor appetite, poor sleeping,
with labored breathing, that child should not be at school. Likely they
need to be seen by the doctor!
Even though school and normal activities are fine, please be
cautious about letting your coughing child be around any vulnerable
newborns. I recognize that siblings present a uniquely complex issue. It
is usually not reasonable or even possible to try to quarantine them
for weeks.
Check out the links below for help with symptomatic treatment
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