Pertussis (Whooping Cough): Nothing to Sneeze At
“The difference between what we do and what we are capable of doing would suffice to solve most of the world's problems.” Mahatma Gandhi
Not your run-of-the-mill cough, Pertussis, or whooping cough, is an acute infectious disease of the respiratory tract caused by the bacterium Bordetella pertussis. Outbreaks were first described in the 16th century, and the organism was first isolated by Jules Bordet (thus its name) and Octave Gengou in Paris in 1906.
A striking clinical feature of pertussis is a racking cough with a high-pitched sound or “whoop” when breathing in after a coughing episode. Other associated symptoms can include bluish skin (cyanosis) during a coughing attack, vomiting (following a cough attack), and exhaustion.
But whooping cough is a great pretender, acting like a common cold with a runny nose and low-grade fever for the first two weeks. Then the cough becomes severe and can stick around for 10 or more weeks (earning its nickname, the “100-day cough”).
Why pertussis needs more attention? Everyone can agree that it’s important to get your priorities straight. One thing that has always intrigued me about the daunting list of global infectious diseases is how priorities are set in dealing with them. Odds are pretty good that pertussis isn’t on your priority list. After reading this blog, however, I believe you’ll add it.
But first, here are some of the characteristics of infectious diseases that I think should be factored in when prioritizing them: 1) the number of people who are affected; 2) risk of spread (contagiousness), 3) severity: risk of illness leading to hospitalization or death; 4) age (more weight given to newborns and young children); 5) availability of effective treatment; and 6) last, but certainly not least—preventability by changing behavior or most important by immunization. As you will read, pertussis scores highly on all of these factors.
How many people acquire pertussis? Worldwide, there are an estimated 24.1 million cases of pertussis annually. About 90% of all cases occur in developing countries. In 2012, the most recent peak year, the Center for Disease Control and Prevention (CDC) reported 48,277 cases in the U.S., but many more go undiagnosed and unreported. Since the 1980s, there has been an increase in the number of cases reported to the CDC.
How contagious is pertussis? Whooping cough is extremely contagious. It is spread by droplets through coughing, sneezing, or simply by close contact with an infected person.
Who is at risk of serious disease? Anyone can get pertussis, but newborns are most vulnerable. A recent report, indicated that pertussis is responsible for 160,700 deaths globally per year. (According to the World Health Organization [WHO], in 2018 fewer people died of measles, about 140,000. Both diseases share a predilection for children and are vaccine-preventable.) Pertussis can cause serious illness in people of all ages and can be life-threatening, especially in babies. Approximately half of babies less than 1 year old who get pertussis require hospitalization.
How is pertussis treated? Treatment with antibiotics, such as erythromycin and related drugs, or trimethoprim-sulfamethoxazole, relieves the symptoms of pertussis, but treatment must be given during the early stage of the illness. If antibiotics aren’t started before three weeks of coughing, they are no longer recommended. Antibiotics can also be given to close contacts of someone with pertussis. People who have completed five days of antibiotics no longer spread the disease.
Decisions regarding who to treat, with what, and when should be guided by a physician. The same can be said about diagnostic tests (obtaining nasal swabs for culture) and the management of newborns and infants.
Can pertussis be prevented? There are two pertussis vaccines: DTaP and Tdap. Both vaccines are given with tetanus and diphtheria. Your age determines which vaccine and how many doses you need. Researchers believe whooping cough occurs more frequently in older adults than has been previously recognized. Also, research has shown that immunity to B. pertussis can wear off over time. That's why all adults 65 years of age and older need to get a booster shot.
Babies do not start building their own protection against whooping cough until they begin vaccinations at two months of age. To avoid this gap in protection getting the Tdap vaccine during the third trimester of pregnancy is recommended.
While safer than the older whole-cell vaccine, the current pertussis vaccine is not as effective. This has been shown to be due to mutation of B. pertussis. Researchers are frantically working on developing a better vaccine, but it is nowhere near ready.
While immunization is the best way to prevent pertussis, you should also avoid contact with others who are coughing, wash your hands frequently, cover your cough with a tissue or cough into your sleeve, and seek medical attention if you develop pertussis-like symptoms or have been exposed to someone with pertussis.
Vaccine hesitancy is not as big a challenge with pertussis as it is with measles vaccine (for example, see the September 6th blog: “Fueled by Vaccine Hesitancy, Measles Is Going Viral”). Nonetheless, anything that lessens uptake of these vaccines limits what we are capable of doing in solving these global infectious disease problems. Sadly, children bear the brunt of such inaction.