Wednesday, July 25, 2012

Pertussis in Washington

In my Ecological Anthropology class, we have a section on infectious disease, and a day dedicated to herd immunity and the vaccination wars. For any students who may be interested in following up on that topic, check out this post on the pertussis outbreak in the state of Washington, which has seen a 13-fold increase in cases this year, relative to last year.

Pertussis (whooping cough) is a major health risk to infants, in particular, but it's no fun for healthy adults, either. Washington is in the middle of a major outbreak, partly related to the percentage of unvaccinated people, which is really high on the Northwest Coast, although the CDC suggests that resistance to the vaccine, and a natural cyclicity in outbreaks of the disease are also to blame. 

Note that the numbers are probably underestimates of pertussis cases. Pertussis is hard to diagnose after the first few weeks, and in adults - particularly vaccinated adults - it often doesn't include the classic "whooping" sound to aid diagnosis. Also, there's nothing that can be done about pertussis, per se, so there's not much point in running the expensive diagnostic test. Doctors may assume a patient has pertussis, if the person has the symptoms and was known to have been exposed, but those diagnoses may not be reported to the CDC. 

Speaking from personal experience, pertussis can also be missed. I'm fairly certain I had pertussis this Spring. In mid-March, I developed a cough so severe that I would throw up at the end of coughing jags, turn bright red, even start to see black around the edges of my vision. Four months later, I still cough when I laugh or breathe too deeply. I was on an airplane from Minneapolis to Washington DC at exactly the right time to have caught pertussis, and Minnesota is also experiencing an outbreak this spring. But my case was never counted. The doctors assumed it was a normal cold, just made more severe by my pregnancy, and by the time it was clear that I had a bigger problem, it was too late for a definitive test.

So, these outbreak numbers are probably underestimating the true scope of the problem. Keep your kids safe - vaccinate!

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