Pertussis: the other vaccine-preventable respiratory disease that we can’t get rid of.
Let me tell you about how I got whooping cough. Actually, I don’t know how I got it. I just started feeling unwell one day, almost unnoticeably. I had a very low-grade fever and general malaise, but it lasted for a few weeks, so I made an appointment with a doctor. I had moved to Washington State six months before, and I didn’t yet have a GP. By the time my appointment came around, I had been coughing sometimes in the evening, coughing fits that were uncomfortable but not alarming. I was seen by a woman who took my temperature and looked at my throat, listened to my symptoms, and said “You have a virus. What do you want me to do? It will pass.” I was sent home.
Pertussis, also known as whooping cough, is a highly contagious respiratory illness caused by a bacterium called Bordetella pertussis — each infected person infects on average 5 other people, about double the transmission rate of Sars-Cov-2, the virus that causes Covid-19. It’s transmitted via droplets when an infected person coughs or sneezes, and symptoms can show up anywhere from 5 days to three weeks after infection. Early symptoms can last for a week or two, and include a runny nose, a low-grade fever, and a mild cough — in other words, the early symptoms aren’t unlike the symptoms of the common cold. Pertussis is most transmissible in this early stage, when whooping cough hasn’t yet been suspected. Infants might experience apnea, which is an unusually long pause in breathing. After the first few weeks, the more recognizable symptoms of whooping cough start to appear, such as violent, rapid coughing fits over and over until the lungs are emptied of their air, which causes a “whooping” sound when air is finally inhaled. These fits can be followed by vomiting, and are most certainly followed by exhaustion. The coughing fits are more frequent at night, and adults often experience more severe disease than adolescents. Infected babies under a year old often don’t cough at all, but rather struggle to breathe or stop breathing and turn bluish, and about half of them need to be hospitalized. This phase of the illness can last up to 10 weeks, and worsens over that time to produce increasingly frequent coughing fits. In addition to the coughing, pneumonia, urinary incontinence, dehydration, and weight loss are relatively common complications of pertussis.
Contrary to the the dramatic symptoms in some, in others the telltale “whoop” may be absent, particularly vaccinated teenagers adults, and many adolescents and adults can also be completely asymptomatic; asymptomatic carriers can efficiently spread the infection.
Disappointed and made to feel a little bit like a hypochondriac, which I’m not, I gave up on figuring out what was wrong until I couldn’t ignore it anymore. Within weeks of going to the doctor, I was coughing so much every evening that I couldn’t keep down my dinner. It was severe, and I felt like I couldn’t breathe when the coughing fits overcame me. I would cough until I came close to fainting, and then the fit would stop. I felt horribly sick, but the doctor had said it was just a virus. She hadn’t heard me cough, as it wasn’t bad when I had gone in; my coughing fits were mostly at night, and she had written me off in a way that entirely discouraged me from going back. I was in my 20s and not feeling particularly mortal, so I assumed it would eventually go away on its own. As I had recently started new jobs, I had little sick leave available to use, so every day I went to work as a teacher at a community college and at a state governmental agency. Nights, I coughed until my entire body hurt and I was drained of all energy.
One Saturday night, months into my undiagnosed illness, it hurt so much to cough that I couldn’t bear the pain anymore. I was afraid of coughing, afraid of breathing, afraid of moving for fear of the burning and sharp pain in my lungs. The following morning, my husband brought me to the emergency room. An x-ray revealed that three fractured ribs were causing my pain. I told the doctor that I had terrible coughing fits every night, and he agreed that was what had likely caused my ribs to fracture. No blood sample was taken. No further investigation into why I had been coughing for months. They had found the root cause of the pain and weren’t concerned with the cause of the cough. I was sent home. The next day, I got up and went to work. It hurt to lift my arm to write on the whiteboard. I don’t remember coughing at work, and I hope that I didn’t pass my illness on to any of my students, many of whom were grandparents who could have spread it to their grandchildren.
Pertussis is diagnosed by various methods, including physical examination, a blood test (to check for high white blood cell counts indicative of infection but not specific to whooping cough), and a nose/throat culture (PCR) test. It’s treated with antibiotics, and the treatment is usually helpful in reducing symptoms and transmission if it’s administered in the first three weeks of the illness. Treatment after three weeks past infection is unfortunately not helpful, as the bacteria does not live beyond three weeks in the body, even though symptoms continue. That is what’s so tricky about this illness.
A few weeks later, the evening news ran a story about children with whooping cough in the whooping cough epidemic in Washington State. As we watched a video of a child cough and “whoop” as he struggled to breathe in between coughs, my husband and I looked at each other and didn’t even have to say out loud that the cough I’d had for three months sounded like the child’s whooping cough. You may wonder if I had been vaccinated against pertussis, and the answer is that yes, I’d had the routine childhood vaccination. The next day, I went to the emergency nurse at my health co-op and I explained my symptoms. I didn’t say “whooping cough” because I was curious if any health care professional would suggest it on their own, and to my relief she said it before I did, reassuring my faith in my healthcare co-op. “I think you have whooping cough, and I’m going to take a test to confirm it, but if you’ve had it as long as you say, then the test will come up negative. The bacteria is likely out of your system by now.”
Before widespread pertussis vaccination of children in the 1940s, up to 270,000 cases were reported in the US each year, resulting in up to 10,000 yearly deaths; as a significant number of pertussis cases go undiagnosed and unreported, the actual number of infected individuals was likely much higher. As an increasing percentage of the population was vaccinated, in 1976 only 1010 annual cases were reported. However, neither infection nor vaccination results in lifelong immunity to pertussis. Pertussis is the most prevalent vaccine-preventable disease in the developed world (this status may currently be disrupted by Covid-19). Pertussis has not been eradicated through vaccination, and is now considered an endemic disease (a disease that’s always present in a population, as malaria is in some parts of the world, and as Covid-19 is expected to become), with epidemic peaks occurring every 2 to 5 years. In 2012, for example, nearly 50,000 cases of pertussis were reported in the US (with particularly large outbreaks reported in Washington state, Minnesota, Vermont, Wisconsin, and California), the most reported cases since 1955. The same year saw large outbreaks across the world.
In spite of widespread vaccination programs, which are effective in reducing serious disease in those most at risk for serious complications (children under one year of age), the currently-used vaccine is possibly not effective in reducing transmission, and vaccine exemptions given in some states means that herd immunity is now lower than it was after the initial vaccination drives. Some studies have cited the increased use of acellular vaccines, rather than the inactivated whole-cell vaccines previously used, as a possible cause of increasing infection rates. While it has more adverse side effects, the inactivated whole-cell vaccine has been shown to have a higher efficacy in preventing infection than acellular vaccines. In addition, immunity to the bacteria that causes pertussis wanes in the years following vaccination, and some countries have added booster shots to their vaccination schedules to counter this effect. As of 2015, the US recommends pertussis inoculation three times in the first year of life, once in the second year of life, and once more between the ages of 4 and 6, one in early adolescence, and one for women in the third trimester of pregnancy.
As predicted, my PCR test came up negative, meaning that my case would never show up in the data as a positive case, just as a suspected case. In 2002, the year I had whooping cough, 575 people were diagnosed with pertussis in Washington State, a three-fold increase from the previous year. Actual numbers are likely much higher. In 2012, there were over 900 diagnosed cases. In 2018, the most recently reported year, there were 630 cases of pertussis diagnosed. The numbers wax and wane as herd immunity varies. My case is not represented in the numbers. I was still given erythromycin, at the time the antibiotic of choice for pertussis, just in case there were any bacteria still in my system. Every time I took it, I had stomach aches and spiked a fever. Once my doctor changed me to azythromycin, which has since displaced erythromycin as the choice antibiotic to treat pertussis, the medicine-induced fevers stopped, but my condition didn’t show any rapid improvement. Of course, by the time my diagnosis had come, the bacteria had left my body and I was just left with the aftermath; the damage had already been done. After a few more months, my cough had faded, only to be replaced with asthma. My fatigue lasted for months, and the painful ribs for years, only to be re-injured in each of my pregnancies years later.
My husband never got pertussis. Or did he? Was he the asymptomatic carrier who gave it to me? Women are significantly more likely than men to be diagnosed with pertussis, but it is not entirely clear whether this is caused by increased exposure, higher diagnosis rates, chromosomal or hormonal differences, or some other factor. Pertussis is so contagious that up to 90% of susceptible household contacts acquire it from an infected person. Did I contract it from one of my students? Or one of my co-workers? Or somebody I passed by at the grocery store? I’ll never know. Studies have shown that immunity from vaccines provides greater immunity to the disease than infection itself. What I do know is that I’ll be getting my booster shots regularly.
• Annual Communical Disease Report 2002, Washington State Department of Health
• Cherry, James D., et al. “Epidemic Pertussis in 2012 — The Resurgence of a Vaccine-Preventable Disease: NEJM.” New England Journal of Medicine, 30 Aug. 2012, www.nejm.org/doi/full/10.1056/nejmp1209051.
• De Greeff, Sabine C., et al. “Estimation of Household Transmission Rates of Pertussis and the Effect of Cocooning Vaccination Strategies on Infant Pertussis.” Epidemiology, vol. 23, no. 6, 2012, pp. 852–860., www.jstor.org/stable/41739684. Accessed 11 Apr. 2021.
• Epidemiological Alerts and Updates 2012. Annual Report 2012. Pan American Health Organization First Edition: May 2013. https://iris.paho.org/bitstream/handle/10665.2/50525/Reportepialert2012_eng.pdf?sequence=2&isAllowed=y. Accessed 10 Apr. 2021.
• Giovanni Gabutti, Chiara Azzari, Paolo Bonanni, Rosa Prato, Alberto E Tozzi, Alessandro Zanetti & Gianvincenzo Zuccotti (2015) Pertussis, Human Vaccines & Immunotherapeutics, 11:1, 108–117, DOI: 10.4161/hv.34364
• Kathryn M. Edwards, Michael D. Decker, 44 — Pertussis Vaccines, Editor(s): Stanley A. Plotkin, Walter A. Orenstein, Paul A. Offit, Kathryn M. Edwards, Plotkin’s Vaccines (Seventh Edition), Elsevier, 2018, Pages 711–761.e16, https://doi.org/10.1016/B978-0-323-35761-6.00043-2., (https://www.sciencedirect.com/science/article/pii/B9780323357616000432)
• “Signs and Symptoms of Whooping Cough (Pertussis) | CDC.” Centers for Disease Control, www.cdc.gov/pertussis/about/signs-symptoms.html. Accessed 13 Mar. 2021.