Understanding pertussis

Pertussis is commonly called whopping cough or “the cough of 100 days”,¹ It is a respiratory infectious disease caused by a specific bacterium called Bordetella pertussis.

The spread of this infection occurs through water droplets emitted from sneezing and coughing. The initial symptoms include mild fever, cough and a runny nose. This gradually develops into a hacking cough, followed by a whooping cough. These symptoms occur 7-10 days after the person becomes infected by the bacterium. People with pertussis can spread the infection to others up to 3 weeks after the initial symptoms start showing.²

It has been observed that Pertussis can affect 100% of all the household contacts who are non-immunized. There is a high risk of acquiring Pertussis in pregnant women, when in contact with an infected person, or with a lack of immunization. Pertussis can infect all age groups of people, however, it is increasingly dangerous and fatal in infants.¹

According to the Centre for Disease Control and Prevention (CDC), it is estimated that there are at least 24.1 million reported cases of pertussis alongside at least 160,700 pertussis-related deaths reported in children who were younger than 5 years each year worldwide.³

Effects Of Smoking On Respiratory Health

Before understanding the relation between pertussis and smoking, let us review how smoking can affect the respiratory health of an individual.

A systematic review and meta-analysis conducted on the effects of smoking on the respiratory system determined that people who smoke are at least 11 times more susceptible to lung cancer compared to non-smokers and, passive smokers have an increased risk of 1.41 times. When it comes to Chronic Obstructive Pulmonary Disease, smokers are 4.01 times and passive smokers are 1.41 times more susceptible compared to non-smokers. Adult smokers are 1.61 times more susceptible to asthma and 1.57 times more likely to develop Tuberculosis.⁴

Smoking tobacco products usually affects respiratory health by depositing various toxins and carcinogens into the respiratory tract including the airways and alveoli,⁵ In addition, smoking also has a profound effect on the immune system of an individual. A recent study conducted on 1000 participants has revealed that when it comes to smokers, there is a heightened response to inflammation along with an impairment in the activity of certain cells linked with immune memory. Apart from this, there is also a decreased level of cell activity with regard to killing foreign pathogens.¹¹ It was also demonstrated that this long-term effect is linked to variations in DNA methylation, which simply implies that smoking has the potential to alter the gene expression that are involved in immunity metabolism of the cells.⁶

Evidence of smoking Influence on Pertussis risk

As we have an established fact that smoking affects both the functioning of the respiratory system and also impairs the immunity system of an individual, it is quite easier to connect the dots.

Now we can answer the actual question that this article is directed towards. Does smoking have any direct or indirect influence on the risk of pertussis? And the answer is YES. There are some major studies that show that smoking can cause worsened symptoms of pertussis and also an increased risk of pertussis-related hospitalizations.

There is clear evidence that shows that individuals with COPD, asthma, reduced immunity and those who smoke are at an increased risk of complications and hospitalization with respect to pertussis infection.⁷

In a particular study that evaluated patients with pertussis, it was clearly found that a significant proportion of patients who were hospitalized with an infection of pertussis were smokers which gives a clear link between the severity of symptoms and smoking. Also, during an outbreak of pertussis in Quebec, Canada, individuals above the age of 12 who smoked had an elevated risk and symptoms of sinusitis, paroxysmal cough and a disrupted pattern of sleep compared to those who did not smoke. Furthermore, COPD patients who smoked have shown a high risk of developing pertussis.⁸

Overall, the current existing evidence shows that smoking can influence the severity and risk of pertussis, especially for those who have underlying conditions like COPD or asthma.

An Invitro model suggested that smoke exposure from cigarettes was directly linked to the B pertussis bacteria binding to the cells of the buccal epithelium (which forms the inner surface of the cheek) as compared to that of non-smokers.⁹

What is to be noted is that individuals with pertussis who smoke are more infectious compared to non-smokers and this is due to increased levels of cough and severity in them.¹² This observation is significant as it was observed that members in the household are the major source for at least 60% to 83% of infant pertussis cases.¹³

Prevention of pertussis

Currently, DPT ( diphtheria, pertussis, tetanus ) vaccination is the most sought-after preventative method for pertussis. Centre for Disease Control (CDC) recommends that children below 11 years should receive a DTaP vaccine and teens above 11, adolescents above 19 and adults are recommended to have a Tdap shot. Adults who smoke are suggested to take a DPT vaccine as they are more vulnerable to complications and severity of the disease.¹⁴  

Summary

Understanding the intricacies between the risk of pertussis and smoking plays a significant role in the devising of some effective public health interventions. Pertussis/whopping cough which is caused by the bacterium Bordetella pertussis, has the potential to be extremely contagious and fatal, especially with respect to infants and in those people who are not immunized. Although the current vaccinations have played a major role in reducing the prevalence of the disease, smoking remains an exacerbating factor and this calls for some comprehensive and critical approaches when it comes to the management and prevention of this disease.

Healthcare professionals and public health practitioners should play a crucial role in educating the general public, especially teenagers and adolescents about the less spoken risks that are incurred by smoking, especially in relation to infections like pertussis. An integration of anti-smoking programs with campaigns of vaccination can majorly enhance and play a positive role in improving the respiratory health and thereby reducing the severity of pertussis. Receiving a Tdap vaccine is particularly important for smokers as it helps create an additional protective layer against the infection.

We can conclude through this article that while prevention programs like vaccination play a pivotal role in preventing the disease, addressing risk factors like smoking can significantly reduce the disease burden.