When you hear the phrase “whooping cough,” you may think of an ancient scourge that terrorized people for generations but that can’t possibly be a threat to us in the 21st century. But whooping cough, also known as pertussis, is a real danger to everyone, especially infants. Knowing what pertussis is, how to recognize it, how to treat it, and how to prevent it are keys to keeping your baby healthy.
What Is Pertussis?
Pertussis is a respiratory illness caused by the bacteria Bordetella pertussis. It is highly contagious, and spread by respiratory droplets expelled by those infected, usually by coughing. The incubation period is 7 to 10 days, but may take as long as 21 days. The disease has been around for centuries, and was first recognized in the Middle Ages.1
In the first half of the 20th century, there were as many as 250,000 cases of pertussis each year in the U.S., resulting in thousands of infant deaths each year. After the advent of the pertussis vaccine in the 1940s, pertussis declined by 99%. The incidence of the disease reached its lowest point in 1976, when only 1,010 cases were reported in the U.S.2,3
But the disease never disappeared entirely. One reason for this is that, unlike many other childhood illnesses such as chicken pox, infection or vaccination with pertussis does not provide lifelong immunity. So people who were vaccinated as infants will have their immunity wane, and then get the disease as teenagers or adults. As a result, the illness is on the rise: in 2012, for example, there were 48,277 cases reported in the U.S., the highest number since 1955.3
The population who contracts pertussis has changed with time. Historically, pertussis was most common in those between 1 and 5 years old. But the age of those affected has shifted in the past few decades. In 2015, 55% of the pertussis cases were in those age 10 years or older.3
There are several reasons for this shift in age. One is that the vaccine was changed in the 1990s to make it safer, but it is less effective, and immunity wanes more quickly. Vaccine refusal is another factor. And teenagers and adults are important reservoirs of pertussis in the community, and transmit the virus to infants and children who suffer much greater consequences.3
What Are the Symptoms of Pertussis?
There are usually three stages to pertussis infection. The first stage looks like the common cold, with mild cough, congestion,runny nose, mild sore throat, and low-grade fever or sometimes no fever. This can last for 1-2 weeks, though often less time in infants.2-4
The next phase is marked by fits of coughing. Infants and children will often make a “whoop” noise on inhalation after a coughing spell, which gives the illness its name. This sound is distinctive, and can be seen in videos here and here. In teens and adults, this “whoop” may not be heard, and so there is little thought that the person has pertussis.
Likewise, infants may not “whoop,” either, but may have apnea, a serious pause in breathing. Obviously, this can be dangerous for infants, and is the reason that pertussis can be fatal. Older children, teens, and adults don’t experience apnea from pertussis, so although the disease is only a nuisance for them, it can be a matter of life and death for infants.
During this second stage, the patient is exhausted from the endless coughing, and may have decreased appetite. Fever is uncommon during this stage. In infants, the coughing fits may also cause cyanosis (a bluish tint to the skin caused by low oxygen content in the blood), especially around the mouth.2-4
The third phase is marked by decreasing severity and frequency of the cough, but this stage may last for weeks or months. That’s why pertussis is also known as “the 100-day cough,” especially in teens and adults.
Some common complications of pertussis include ear infections, pneumonia, and dehydration.3
How is Pertussis Treated?
Pertussis can be treated with antibiotics, but only if given in the first stage of the illness. But this usually doesn’t happen because at that point, pertussis is indistinguishable from the common cold, for which antibiotics are not prescribed. However, even after the first stage, antibiotics are commonly used because they will decrease the infectivity of the patient, thereby reducing the spread of the disease. In these cases, the antibiotics won’t do much good for the person taking them, but will help keep their close contacts from getting the disease.2-4 Antibiotics are usually given to any infant less than 1 year during the first 6 weeks of illness, and to anyone older than 1 year during the first 3 weeks of illness if pertussis is suspected.3
Because of the risk of apnea, infants less than 6 months old who have pertussis should be hospitalized for monitoring and support.3
How is Pertussis Prevented?
There are two ways to prevent pertussis. First, for those who are close contacts of someone with pertussis, they can be given prophylactic antibiotics (that is, medicine to prevent getting the infection). Decisions to use antibiotics in this way are made on a case-by-case basis, but those at highest risk include infants younger than 12 months, pregnant women in their third trimester, immunocompromised people, and those with chronic medical conditions that might be worsened with pertussis.3
The other way to prevent pertussis is through vaccination. In the U.S., pertussis vaccine is usually given as part of the DTaP or diphtheria, tetanus and acellular pertussis vaccine. The primary series is usually given at 2, 4, 6, 15-18 months and 4-6 years. Because immunity wanes, a booster dose is usually given at 11-12 years old.
Vaccination of pregnant women is also critical. The recommendation is to get vaccinated with each pregnancy between 25-37 weeks, but preferably earlier to allow antibody passage from mom to fetus. And cocooning the baby (having everyone around the baby get vaccinated against pertussis) is another strategy that can protect your infant.
- Kuchar E, Karlikowska-Skwarnik M, Han S, Nitsch-Osuch A. Pertussis: history of the disease and current prevention failure. Adv Exp Med Biol. 2016;934:77-82.
- Nieves DJ, Heininger U. Bordetella pertussis. Microbiol Spectr. 2016 Jun;4(3).
- Daniels HL, Sabella C. Bordetella pertussis (Pertussis). Pediatr Rev. 2018 May;39(5):247-257.
- CDC. Pertussis (Whooping Cough).