Whooping cough

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Whooping cough is an infectious disease caused by bacteria called "Bordetalla pertussis."  Because these bacteria release chemicals that cause inflammation and swelling of the upper respiratory system, severe cough is a hallmark of the condition.

Can whooping cough be prevented?

Whooping cough is highly contagious and spreads from person to person by coughing or sneezing among people in close quarters.  To make matters worse, an infected (and contagious) person can spread the disease without knowing they have it.

Yet there is an effective way to prevent whooping cough:  vaccination.   Before the widespread availability of pertussis vaccination in the 1940s, around 200,000 kids developed whooping cough and around 9000 died each year in the US; far fewer cases (up to 40,000) and deaths (up to 20 or so) are attributed to whooping cough now that vaccinations are routinely recommended.

Vaccination is recommended by the CDC for all babies, children, teenagers and pregnant women as well as for any adult who has never received the vaccination.  Prevention is most important for babies since they tend to have the most severe (and even fatal) infections.

The whooping cough vaccine is usually provided in combination with diphtheria and tetanus vaccinations (called DTaP or Tdap).   It's considered about 80%-90% effective; that means it's possible to get vaccinated and still develop whooping cough.  In addition, immunity can wane years after vaccination so outbreaks may occur among those who did not receive a booster as a preteen or teenager as recommended.  When it does occur in vaccinated people, the disease tends to be less severe.

In recent years, there's been an increase in whooping cough in the US – at least part of the increase could be due to the 'anti-immunization' movement.

Symptoms of whooping cough

Despite its name, whooping cough does not always start out with a severe cough.  It may initially seem like a cold with a runny nose, fever and cough.   And babies may not have a cough at all; pauses in breathing (called apnea) may be an early symptom instead.  In teenagers and adults, coughing can be so severe that you break a rib or faint.

After a week or two, symptoms may worsen with fits of coughing, a high-pitched sound (or "whoop") that follows bouts of coughing, and throwing up after coughing spells.  In severe cases, oxygen levels may fall causing a blue discoloration to the skin (especially in babies).  The coughing can go on for 10 weeks or more, well after the bacteria are no longer present.

How is whooping cough diagnosed and treated?

When whooping cough is suspected, the diagnosis can be confirmed by testing the blood or from a sample of mucus.  Obtaining the mucus sample is uncomfortable since it is obtained by inserting a swab or tube through the nose.

Whooping cough is treated with antibiotics, such as azithromycin or trimethoprim-sulfamethoxasole.  The sooner treatment begins the less likely it is that it will spread, cause severe symptoms or lead to complications (such as pneumonia).  Other treatments include use of a vaporizer, fluids, and avoidance of irritants (such as smoke or dust) that can set off a fit of coughing.  Good handwashing and covering the nose and mouth when coughing or sneezing can help limit spread of the bacteria that cause whooping cough.

What's ahead?

Researchers are studying the bacteria that cause whooping cough to determine why cases of the disease have become more frequent and ways to improve the vaccine.  Someday, we may eliminate whooping cough in the US and other countries the way polio has been in many countries.  In the meantime, the success of vaccinations at preventing suffering and death could be in jeopardy if people forego recommended vaccinations for their kids and themselves.

Robert H. Shmerling, MD, is associate professor of medicine at Harvard Medical School and Clinical Chief of Rheumatology at Beth Israel Deaconess Medical Center in Boston where he teaches in the Internal Medicine Residency Program. He is also the program director of the Rheumatology Fellowship. He has been a practicing rheumatologist for over 25 years.

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