Whooping cough, also known as “100-day cough,” continues to gain ground in Canada, particularly in Quebec. More than 12,000 cases have been reported since January, according to the Public Health Agency of Canada (PHAC). That’s much higher than the 500 to 4,500 infections reported annually nationally, it added in an interview with CBC News.
The increases in cases are mainly affecting Quebec and Ontario, even if several other provinces have recorded a higher number of cases than usual in recent months.
The number of cases observed in Quebec, New Brunswick, Prince Edward Island and Newfoundland and Labrador in 2024 exceeds the peaks recorded in the years preceding the pandemic, we can read in a press release from PHAC.
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The provinces of Quebec and Ontario are particularly affected by the increase in cases of whooping cough.
Photo : Radio-Canada
A variety of bacterial infections have made a comeback once pandemic restrictions have been lifted. Influenza, respiratory syncytial virus (RSV) and a form of bacterial pneumonia have all reappeared in larger waves or at unusual times, sometimes overwhelming hospitals in Canada and elsewhere.
A convergence of factors
A similar trend is observed in the United States and throughout Europe. The increase in cases worldwide of this disease caused by the bacteria Bordetella pertussis is explained by a confluence of factors.
Given the cyclical nature of whooping cough, its resurgence is not surprising, says Dr. May ElSherif, associate director of the Canadian Centre for Vaccinology in Halifax. What is surprising is the magnitude and scale [de cette résurgence]adds the clinician-researcher.
Immunity from vaccines or from a previous pertussis infection does not last a lifetime, she also notes, adding that the isolation caused by the COVID-19 pandemic has lowered overall immunity rates from natural exposure. Misinformation about vaccines that has circulated online has also increased vaccine hesitancy.
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A vaccine against whooping cough (File photo)
Photo : Reuters / Lucy Nicholson
However, it should be noted that the usual vaccination programmes were seriously disrupted, requiring years of catching up.
For example, globally, the vaccination rate for the three-dose diphtheria, tetanus and pertussis (diphtheria, tetanus and pertussis) vaccine Tdap fell from approximately 86% in 2019 to 83% in 2020. According to estimates by the World Health Organization (WHO) and UNICEF, this means that 22.7 million children worldwide have not been vaccinated.
Where does the name whooping cough come from?
After a coughing fit (an episode of prolonged and uncontrollable coughing), the infected person may, when inhaling, emit a noise reminiscent of a rooster crowing. This is why the name whooping cough was given to this disease. This cough becomes stronger and more frequent after 7 to 14 days.
The person may also wheeze or stop breathing for a few moments.
A cyclical infection
Whooping cough tends to spread more in some years than others. It’s not uncommon to have localized outbreaks of whooping cough, notes Dr. Anna Banerji, a pediatric infectious disease specialist.
The rapid evolution of some pathogens and patterns of immunity in the population, among other things, explain the tendency of whooping cough to rise and fall in three- to five-year cycles, says Dr. Amesh Adalja, an infectious disease specialist and researcher at the Johns Hopkins Center for Health Security in Baltimore.
The latter emphasizes that people at risk provide nothing more or less than fuel for bacteria to trigger epidemics.
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Whooping cough is a bacterial infection, not a virus, and can be treated with antibiotics. (File photo)
Photo : Radio-Canada / Lauren Pelley
A potentially fatal disease
Whooping cough is highly contagious and can lead to serious infections such as pneumonia – the most common cause of death – brain damage and even death. According to the Quebec government, 95% of deaths from this infection occur in newborns under 3 months old.
Health Canada’s website states that mortality remains rare in industrialized countries and even more so among adults. Nevertheless, whooping cough affects one in a thousand unprotected children, the most vulnerable cohort in the country.
Vaccination during pregnancy and at 2, 4 and 12 months is the best way to protect little ones against whooping cough, reminds the Quebec government.
The greater vulnerability of young children is explained in particular by the fact that they have not yet received protection against this respiratory infection, explains Dr. Jesse Papenburg, clinician-researcher at the Montreal Children’s Hospital and for the Research Institute of the McGill University Health Centre.
In adults, although symptoms are usually mild, some people break ribs while coughing very violently.
The “100-day cough” is particularly prevalent in developing countries, where 95% of whooping cough cases worldwide occur, according to WHO estimates.
Adaptation of the report by Lauren Pelley (New window) de CBC News