Monday, September 3, 2012

Whooping Cough: Making A Comeback?

With kids going back to school, and in close quarters with their mates, it might be worthwhile revisiting a bug making a bit of a comeback.

In our city, there was a small spike of whooping cough (pertussis) over the summer, with half of them coming from unvaccinated kids. Other reported increases have been occurring within the province, within Canada, and within the U.S.

What Is Whooping Cough?
Whooping Cough, or Pertussis, is a highly infectious bacteria. First described in the year 1679, Bordetella pertussis translates as "violent cough". The Chinese coined the phrase "the cough of 100 days" because of its chronic nature.

The classic inspiratory whoop following a paroxysmal cough in children is not always present, especially in teens and adults and may contribute to some missed diagnoses. Other typical features include a cough lasting more than 2 weeks, sudden onset coughing spells, sometimes associated with vomiting. Fever is often NOT present or low.

How Do You Catch It?
The actual bug is a gram negative coocobacillus that is slow growing and highly virulent, meaning that those people who are exposed and unvaccinated are very likely to contract the disease. Attack rates range from 90-100 percent when NOT vaccinated. Transmission is by exposure to respiratory droplets from infected individuals.

Before vaccines were given against Pertussis in the 1940's, upwards of 200,000 cases of pertussis were reported annually in the United States. Epidemics spiked every 3-4 years without respect to seasons.
Infection rates decreased 150 fold after introducing vaccines, and spikes continue to occur when vaccination rates decline. (Britain saw a huge spike several years ago when there was unwarranted concern with respect to links to autism.)

Classic Presentation
The classic presentation is in 3 stages; Catarrhal stage, Paroxysmal stage, and Convalescent stage.
In the Catarrhal stage, lasting 1-2 weeks, the individual feels rundown with mild cough, perhaps low grade fever and runny nose. (Like a common cold.)

The Paroxysmal stage can last 2-4 weeks and is when people get more concerned. The cough is defined as sudden, repetitive coughing with up to 10-30 coughs per spasm. A whoop may or may not follow, and is more common in kids than older individuals. Posttussive vomiting is not uncommon, and fever may or not accompany this phase.

The Convalescent, or recovery stage, can last months and the cough should decline, but may continue to wax and wane.

Diagnosis and Treatment
Diagnosis is often clinical, but definitive diagnosis is by having a nasopharyngeal swab done. The time to diagnosis is several days, and treatment should probably get started prior to final diagnosis. First line treatment is straight forward and effective, so see your physician sooner than later.

Finally, immunization for both kids and ongoing boosters for adults should be the critical preventive method.
Immunity against pertussis wanes, and in Ontario, we have added the acellular pertussis vaccine to our tetanus booster given every 10 years.

Epidemics in schools should prompt review of your kids boosters, as well as your own.
I strongly advocate following our immunization program.

Let me know what you think.
Have you had any local outbreaks where you are?

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