Pertussis (whooping cough)

Infant receiving vaccine

Pertussis, also known as whooping cough, is a highly contagious respiratory disease. It is caused by the bacterium Bordetella pertussis.

Pertussis is known for uncontrollable, violent coughing which often makes it hard to breathe. After fits of many coughs, a person with pertussis often needs to take deep breaths which result in a "whooping" sound. Pertussis can affect people of all ages, but can be very serious, even deadly, for babies less than a year old.

The best way to protect against pertussis is by getting vaccinated.

Symptoms

The disease usually starts five to 21 days after exposure to the bacterium. Initial symptoms include cold-like symptoms and maybe a mild cough or fever. In babies, the cough can be minimal or even not present. In its early stages pertussis appears to be nothing more than a common cold, so it is often not suspected or diagnosed until more severe symptoms appear.

The bacteria attach to the cilia (tiny, hair-like extensions) that line part of the upper respiratory system. The bacteria release toxins (poisons) that damage the cilia, causing the airways to swell, leading to difficulty breathing.

As the disease progresses over the course of a week or two, the traditional symptoms of pertussis may appear. Pertussis can cause violent and rapid coughing, over and over, until the air is gone from the lungs causing a loud "whooping" sound on inhalation. The whoop is not present in all cases. Sometimes the extreme coughing fits (called paroxysm) are followed by episodes of vomiting. These coughing fits make it hard to eat, drink, breathe, and, as they are more pronounced at night, to sleep. However, in-between episodes, the person seems well. The coughing fits become more common and worsen as the illness continues, sometimes for many weeks or months. The prolonged cough is associated with the toxin that was produced by the bacteria. Even if antibiotics are prescribed to kill the bacteria, the cough may persist.

Pertussis is most dangerous for babies. Babies may have a symptom known as apnea. Apnea is a pause in the child's breathing pattern. Babies are at greatest risk for pertussis-related complications and mortality. Death is infrequent and most likely to occur in unvaccinated infants.

Laboratory Testing

Culture of Bordetella pertussis has been the "gold standard" for pertussis confirmation. However, several factors can contribute to false negative results including: inadequate collection or transport of the specimen, timing of the sample in relation to onset of symptoms, interference from antibiotic treatment, and immunization history. Since Bordetella pertussis tends to adhere to ciliated respiratory cells of the nasopharynx, the best specimen for culture is collected with the nasopharyngeal swab. Final results are usually available seven to 10 days after collection. Negative culture results do not rule out pertussis, especially when compatible clinical symptoms exist. If the specimen was collected after the catarrhal, or early paroxysmal stages, or after antibiotic use, false negatives may occur.

Transmission

Humans are the only host for B. pertussis. The disease is spread by direct contact with discharges from the nose and throat of infected individuals during the cold-like phase and for about two weeks after the onset of cough. The disease is spread by coughing or sneezing when in close contact, such as within three feet, with face-to-face contact, and especially in enclosed areas. Babies are often infected by older siblings, parents, or caregivers who might not even know they have this infection, especially before the severe cough presents.

Around three weeks after the cough starts, the person is less likely to spread the infection to others. Those who are treated with antibiotics are no longer infectious after five days of antibiotic therapy.

Untreated infants less than one year of age could remain infectious for up to six weeks after onset.

Prevention

Get immunized

  • See that your children get their full immunization series on time.
  • If you are pregnant get a Tdap with each pregnancy between weeks 27 and 36. By getting Tdap during pregnancy, mothers build antibodies that are transferred to the newborn, providing protection against pertussis in early life, before the baby can start getting DTaP vaccines at 2 months old. Tdap also helps to protect mothers, making them less likely to transmit pertussis to their babies.

Cover your cough

  • Cough or sneeze into your upper sleeve or elbow, not your hands, if you don't have a tissue.
  • Wash your hands often with soap and water for at least 20 seconds.
  • Use an alcohol-based hand rub if soap and water are not available.
  • Avoid close contact with people who are coughing.

Protect babies from close contact with people who are coughing

  • Make sure everyone around the baby is up to date with their pertussis vaccines. Parents, siblings, grandparents, babysitters, should be up to date with the age appropriate vaccine (DTaP or Tdap) at least two weeks before coming into close contact with the baby. Adults need one Tdap in a lifetime.
  • If you are told you are a close contact of a person with pertussis discuss with your health care provider about taking antibiotic prophylaxis to prevent infection.
Vaccination

The burden of pertussis infection has been lessened by immunization. Before pertussis vaccines became widely available in the 1940s, about 200,000 children were sick with it each year in the United States and about 9,000 died as a result of the infection. Now we see about 10,000 to 40,000 cases reported each year and unfortunately up to 20 deaths. The pertussis vaccine is given in combination with diphtheria and tetanus vaccines.

There are several formulations of these vaccines used to prevent diphtheria, tetanus and pertussis. Some are combined with vaccines to prevent other diseases and reduce the total number of shots that someone receives at one office visit. In the U.S., DTaP, Tdap, and Td vaccines are most commonly used.

DTaP is given to children younger than 7 years of age, and Tdapis given to older children and adults. Before Tdap, pertussis vaccines were not given after age 6.

Pertussis vaccines are now recommended for people of all ages. Babies and children should get 5 doses of DTaP for maximum protection. A dose is given at 2, 4 and 6 months, another at 15 through 18 months, and again at ages 4 through 6 years. A booster dose using the Tdap formulation is given to preteens at 11 or 12 years old. Tdap should also be given to 7-10 year olds who are not fully immunized against pertussis.

Tdap is similar to the old Td but now also contains protection against pertussis. Adolescents 11 through 18 years of age (preferably at age 11-12 years) should receive a single dose of Tdap. This now protects the recipient not only from tetanus and diphtheria, but also pertussis. One dose of Tdap is also recommended for adults 19 years of age and older who did not get Tdap as an adolescent. Expectant mothers should receive a dose of Tdap during each pregnancy, preferably at 27 through 36 weeks.

Treatment

Antimicrobial treatment generally does not lessen the severity of the disease unless it is initiated in the early phase, prior to paroxysmal coughing. Pertussis is generally treated with antibiotics; early treatment is very important, before coughing fits begin. Treatment reduces transmission and is essential for disease control as the treatment helps prevent the spread of disease to close contacts (those who have spent a lot of time around the infected person). After five days of treatment, the bacteria are gone and infection can no longer be spread to others even though the cough will persist.

Treatment is not indicated after three weeks of cough as the bacteria are no longer present. The residual cough is due to the damage to the ciliated cells already inflicted by the toxin.

If you have pertussis:

  • Take antibiotics when diagnosed with pertussis to protect others
  • Take the entire course of antibiotics as directed by your health care provider
  • Defer from attending the workplace or school until after your fifth dose of antibiotics
  • Cover your cough
  • Stay away from babies, pregnant women and people with chronic lung diseases to avoid spreading the disease to those who could become seriously sick until after five days of antibiotics
  • If you elect not to take antibiotics, stay away from others for three weeks after the onset of the cough
More resources for health care providers

"In 2012, an epidemic year for pertussis in the United States, Vermont reported the second highest pertussis incidence rate (103/100 000 population) in the country. During this period, Vermont Department of Health Laboratory was one of a few laboratories in the nation that routinely cultured all specimens from suspected pertussis cases. This provided a unique opportunity to determine pertactin status for many pertussis cases in Vermont. An initial analysis demonstrated that of those cases with isolates available, >90% were pertactin-deficient. It was in this setting of high pertactin deficiency that we sought to assess vaccine effectiveness (VE) and duration of protection of the 5-dose DTaP childhood series and the adolescent Tdap dose."