Whooping cough: Do you need to worry about this "old fashioned" disease?

Do you know anyone who has had whooping cough? This disease, whose medical name is pertussis, was very common when my parents and grandparents were children. Before the childhood vaccine was widely available, there were about 150,000 cases of pertussis in this country each year, with about 8,000 deaths. Many elderly people can still remember and describe the classic "whoop" that gave the disease its name.

After World War II, a vaccine was developed and, in the US, most children were vaccinated. The number of cases dropped dramatically. By 1976, there were only about 1,000 cases in the US each year. In recent years, however, the number of cases of whooping cough has significantly increased as immunity from the pertussis vaccine fades.  

What is whooping cough?
It is a respiratory infection caused by a bacterium known as Bordetella pertussis (or B. pertussis). It usually starts with symptoms of a typical upper respiratory infection: fatigue, sore throat, and often fever and congestion. Then people develop a cough. The cough is usually dry, without much phlegm (sputum).

After about 10 days to 2 weeks, things change. The cough becomes more prominent with attacks of coughing lasting several minutes at a time. Sometimes the cough is so violent that people vomit after coughing or feel like they are suffocating when they have these coughing attacks.

In between attacks, however, people with whooping cough don't cough and generally feel well. The disease got its name because people can make a "whooping" sound when they try to breathe in after a coughing fit, though not everyone will actually make the whooping sound.

The attacks of coughing may go on for weeks or months. In fact, in China, pertussis is known as the 100 day cough! The average duration of illness is probably about 7-8 weeks.

How do you get whooping cough?
You get it from someone else who has the disease. It is highly contagious. When an infected person coughs, the bacteria are released into the air and if you breathe them in, you can get sick. People are most likely to spread the disease during the first few weeks of symptoms.  

How is pertussis diagnosed?
The diagnosis of pertussis is usually considered if someone has the typical hacking cough, or if someone has a respiratory infection and is known to have been exposed to someone with pertussis. To prove that someone has pertussis, a swab from the back of the nose can be cultured for Bordetella pertussis. It may take up to a week to get results.
More recently, another test known as polymerase chain reaction (PCR) has become the preferred test. The test detects DNA from the Bordetella pertussis organism, and is also done using a swabbed sample from the nose. Antibiotics are prescribed when whooping cough is confirmed early in the course of the disease.

If you have had whooping cough in the past, you develop immunity to the disease and therefore won't get it again. This immunity may last your entire lifetime, or it may fade with time. People who were immunized against the disease in childhood do not get lifelong immunity, which is why we are seeing an increase in the number of pertussis cases in this country. Vaccines have been used for over 50 years in an effort to prevent whooping cough. The traditional vaccine against whooping cough has been given to infants and children since World War II, in combination with diphtheria and tetanus vaccines (DPT). Recently, a purer vaccine (DTaP) has begun replacing the original childhood vaccine. It is given to infants and young children, and causes fewer side effects than the original DPT.

Until recently there was no approved booster vaccine for teens and adults.  Now that's changed. This booster is called Tdap, because it is combined with the booster dose of tetanus and diphtheria vaccine. Tdap can boost fading pertussis immunity and it is currently recommended that this vaccine be given to adolescents and to adults at least once.

The next time you see your doctor, ask whether or not you have been given the Tdap booster. It might prevent that characteristic whoop from being heard in your neighborhood.

Have you had whooping cough?  Have you known anyone who did?  Are you planning to get the pertussis vaccine or booster? 

Diana Post, M.D., is an Assistant Professor of Medicine at Harvard Medical School and a
practicing internist at Brigham and Women's Hospital in Boston, MA. She is also a rheumatologist.

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