Friday, November 6, 2015

Parapertussis/Whooping cough's milder cousin

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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