Pertussis: A-to-Z Guide from Diagnosis to Treatment to Prevention

Pertussis is caused by bacteria. For unimmunized babies and those at high risk, pertussis can be severe or even life-threatening.

I stood outside the closed door of the hospital room where an adorable 6-week-old baby lay all alone in her crib. As I scrubbed my hands in the sink outside the isolation room, an electronic monitor allowed me to hear her breathing peacefully.

Suddenly the quiet was shattered by a fit of coughing. And she couldn’t stop. The coughs came so closely together that she couldn’t catch her breath. I grabbed a mask from above the sink and, pressing it over my face, entered her room. The coughing continued. The pulse and oxygen monitor at her bedside complained insistently that her blood-oxygen levels were dropping. The EKG monitor sounded an alarm that her heart rate was dropping too. And she continued to cough. Even before I reached her bedside, I could see that her face was turning blue. She began to vomit.

Moments later the peace had returned. Her various monitors beeped tranquilly. The coughing spasm was over. This little girl with pertussis survived, but she had many more weeks of coughing spasms before she could return home to her parents.

What is it?

Pertussis is caused by bacteria that attach themselves to the cilia (little hairs) that line the respiratory tract. These bacteria produce a potent toxin that inflames the respiratory tract and prevents the cilia from functioning properly. The disease can be serious or fatal in infants and unimmunized children. It is much milder in teens, adults, and in immunized children, but it can still be a real nuisance. As you might guess, it can be far worse in people with asthma or with immune deficiencies.

Who gets it?

I have spoken with many parents who believed that pertussis was a disease of the past. Nevertheless, pertussis is a common cause of chronic cough illness in adults and older children. A study published in the June 15, 2001 issue of Clinical Infectious Diseases found that pertussis was the cause of chronic cough in 19.9 percent of the patients studied.

For healthy teens and adults, this is usually nothing more than a long nuisance (lasting months, sometimes with vomiting). For unimmunized babies and those at high risk, pertussis can be severe or even life-threatening.

Pertussis, or whooping cough, which once ravaged children around the world, is again on the rise. Worldwide, about 300,000 people die from pertussis each year. Serious disease is uncommon where immunization rates are high. Still, about 1 out of every 200 babies who get pertussis in the US will die from it. Another 1 out of every 200 will have lifetime brain damage. As many as 2 percent will have seizures, 22 percent will get pneumonia, and most (even in this modern era of reduced hospitalization) will be sick enough to be hospitalized. (Red Book Online, 2009)

In the past ten years, we have seen a dramatic rise in the number of pertussis cases in the United States, with multiple outbreaks. From 1965 to 2001, the number of reported cases of pertussis in the United States was consistently well below 10,000. By 2003, it jumped to over 11,000 and in 2012 there were 48,277 cases of pertussis in the United States.

Pertussis is found only in humans.

What are the symptoms?

Classically, people with pertussis go through four stages:

  1. Incubation. For 5 to 21 days after exposure (usually 7 to 10 days), there are no symptoms at all while the bacteria multiply.
  2. Prodrome. For the next 1 to 2 weeks, pertussis is not unlike a cold. People have runny noses, sneezing, and perhaps a low-grade fever. A mild cough begins that gradually worsens.
  3. Paroxysms. The worst part of the illness lasts from 1 to 6 weeks. Spasms or attacks of coughing may come up to 15 times per day. Sometimes, especially in children, the cough is followed by a “whoop” noise as they breathe in rapidly, attempting to get air. Even so, young infants will often turn blue with the spells from lack of oxygen. The coughing spasms can make it difficult to eat, drink, or breathe. The mucus is often thick and sticky. Gagging, choking, and vomiting are common. Sometimes young infants will stop breathing for varying lengths of time between coughing spasms.
    This stage of pertussis is much milder in adults, teens, older children, and immunized children. Often an older child will just report a nagging cough for a month or more. Sometimes they hack up mucus with the cough. Sometimes the cough comes in fits. Once or twice, they might cough until they vomit. Otherwise, they feel pretty well — they just can’t seem to shake the cough.
  4. Convalescence. As if this disease were not already long enough, the cough continues for another 2 to 4 weeks, but gradually becomes less severe and less frequent. Even after the cough seems finally over, the spasms often recur briefly for the next several months, especially during colds and during exertion.

Is it contagious?

Pertussis is contagious through close contact via respiratory tract secretions.

You or your child have been exposed if you spend a total of 5 hours (over a week) in the same room with someone with the disease, if you sit next to someone with pertussis for any length of time, or if you have any contact at all with infected mucus or saliva. Between 70 and 100 percent of susceptible people will catch pertussis if they are exposed.

Currently, most adults and teens are susceptible because the protective effect of their childhood pertussis immunizations has waned. To address this problem, it is now recommended that all teens receive a booster vaccine at 11-18 years of age (preferably between 11-12 years).

Most infants are protected after the first 3 doses of vaccine, but this protection begins to disappear when they are toddlers. After the 4th immunization at 18 months old, 80 percent are protected for the next 3 to 4 years. The 5th dose, at kindergarten entry, protects them for another few years.

A booster dose is recommended during the teen years to bolster immunity to pertussis.

How long does it last?

Pertussis lasts for weeks or months. It has been called the 100-day cough. People remain contagious until they have been on a pertussis antibiotic for 5 days, or until they have been having coughing spasms for 21 days.

How is it diagnosed?

According to the Centers for Disease Control and Prevention, people are considered to have pertussis if they have a cough lasting for at least 14 days (with no other confirmed cause) and any one of the following symptoms (even if they have been immunized):

  • Coughing spasms or fits (coughs coming in clusters)
  • A whooping noise while breathing in
  • Vomiting caused by a cough

The case is called confirmed pertussis if there is a positive lab test or if there has been exposure to someone with a positive lab test.

During a pertussis outbreak, anyone who has a cough lasting at least 14 days (with no other known cause) probably has pertussis, even in the absence of other specific symptoms.

The lab tests to detect pertussis are either slow, cumbersome, not readily available, or often fail to pick up the disease. For this reason many physicians rely on the working definition of pertussis. Also, the number of proven cases reported to the health department vastly underestimates the number of cases in the community.

How is it treated?

Babies younger than 6 months, and all others with potentially severe disease, are likely to need care in a hospital, or even a pediatric ICU.

Several of the medicines used in asthma are often used to help control the cough.

In addition, pertussis is treated with an antibiotic. Unless the antibiotic is given early in the course, it doesn’t much affect the length of the illness, but is still very effective at stopping its spread. People with pertussis are highly contagious for up to 5 days after starting the antibiotic.

How can it be prevented?

The pertussis vaccine, even with its side effects and problems, has saved many lives by stopping the wildfire spread of pertussis epidemics. Recent pertussis deaths in the United States are a haunting reminder that this disease is still lying in wait.

People who have been exposed to probable or confirmed pertussis should either receive a course of preventative antibiotics (and I say this as someone strongly opposed to the overuse of antibiotics), or be kept home from day care, school, or work for at least 3 weeks. If the exposed individual develops symptoms, they should receive antibiotics to prevent further spread of pertussis to others.

Children under age 7 who have been exposed should receive a pertussis vaccine, unless they have already had 4 doses of pertussis vaccine (and the last dose within 3 years), or unless there is a compelling reason not to immunize them. Exposed teens 11-18 years old who have not already received a booster vaccine should receive one.

Whooping cough, Bordatella pertussis.

Last medical review on: October 28, 2013
About the Author
Photo of Alan Greene MD
Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.
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