How Does Pertussis Affect The Elderly Population

Pertussis, commonly known as whooping cough, is an infectious disease of the respiratory tract (airways and lungs) that mostly affects children.¹ People of all ages can be affected by pertussis, but the clinical presentation in adults and the elderly is different from the typical symptoms experienced by children.¹

The elderly often have unspecific symptoms, sometimes only an enduring cough. This complicates early diagnosis and treatment, which are essential to prevent further complications. Older people with comorbidities are especially susceptible to complications and hospitalisations. Since this is a preventable and treatable infection, it is important to know how the elderly are affected by pertussis, which is further explained in this article.

What is pertussis?

Pertussis is a highly infectious disease of the airways and lungs caused by the bacterium Bordetella pertussis. Mostly, children are affected by this infection and its severe outcomes, but people of all ages can be infected.¹

Infection occurs by inhaling contaminated droplets excreted by coughing or sneezing from person to person.² After an incubation period of 7 to 10 days, a symptomatic period of up to several months occurs.¹ Since pertussis is mostly a pediatric disease, the subcategories of this heading refer to the typical pediatric population.

Symptoms

The symptoms manifest in children typically in three stages, each of them lasting for up to 3 weeks:¹ 

Catarrhal stage: the symptoms in this stage are similar to a viral airway infection

• Sore throat
• Running nose
• Low-grade fever
• Dry cough 

Paroxysmal stage

• Coughing attacks over several minutes
• Whooping in inhalation
• Excretion of thick mucus
• Vomiting 

Convalescence stage

• Decline of the symptoms
• In some cases, persisting mild cough

Diagnosis

In suspected cases with typical symptoms, specific laboratory confirmation is recommended. In the early stages of illness, confirmation using PCR or cell culture from deep nasal swabs is recommended. Later on, after four weeks, confirmation through antibody detection in blood serology is necessary.³

Treatment

A confirmed infection should be treated with antibiotics to reduce the severity and duration of the illness and prevent further infections. The antibiotic is selected taking the patient's age, allergies, local resistance of the bacterium and comorbidities into consideration.¹ A post-exposure prophylaxis is recommended for all after close contact with an infected person.¹ For complications including apnea, pneumonia, and convulsions, in-hospital treatment is necessary. Depending on the severity, intensive care unit admission might occur.

Prevention

Pertussis is preventable with vaccination. The pertussis vaccination is part of the routine childhood immunisation schedule in many countries including England. It is an acellular pertussis (aP) vaccine combined with other vaccinations such as the Diphtheria-Tetanus-acellular pertussis (DTaP) vaccine. Since immunisation only gives protection for less than ten years, booster vaccinations are recommended in childhood, as well as for pregnant women, to ensure passive protection of the baby through antibody transmission from mother to baby.⁴ The booster is recommended for all close contacts (grandparents, father etc.) to optimise the herd immunity of the newborn.³

Pertussis in the elderly

Compared to children, older people are less affected by pertussis in numbers. Recent numbers from EU statistics report an incidence of less than 5 cases per 100,000 people in the 60+ age group.⁵ However, we must consider that pertussis is commonly misdiagnosed and under-recognised in the elderly population. Since the elderly play an important role in contracting pertussis and are likely to have complications and hospitalisations, it is important to know how pertussis affects them, aiming for an early diagnosis and treatment.

Symptoms of pertussis in the elderly

Symptoms of pertussis in the elderly are similar to those in the pediatric population but are often milder. The most typical symptoms of pertussis in the elderly are the following:²

• Longer periods of coughing than in children
• Less or no whooping
• Coughing in the night
• Vomiting
• Flushing and/ or sweating

Diagnosis of pertussis in the elderly

Since the elderly population mainly presents with unspecific coughing, initial misdiagnosis is often the case. A study in England⁶ showed that older people with pertussis symptoms were commonly misdiagnosed with other more frequent conditions such as pneumonia, gastroesophageal reflux, COPD, or asthma, leading to wrong treatment and a late diagnosis of pertussis.

In addition to the misleading symptoms, a laboratory diagnosis in the elderly is often difficult due to wrong-negative PCR results and often positive serology due to earlier immunisations or infections³. This could also contribute to late or missing diagnoses. A wrong or late diagnosis causes not only a health burden due to the deterioration of the symptoms or possible complications but also a burden on health resources and economics.

Risk factors of pertussis in the elderly

Pertussis and a more severe course in the elderly are often linked to chronic health conditions with the use of chronic medication, but especially to asthma, smoking and obesity⁷. Since the source of infections in patients older than 50 years are mainly relatives, workmates and household contacts, close living environments such as nursing homes can also be a risk for infection⁸.

Complications of pertussis in the elderly

Pertussis can lead to further health problems. Complications of pertussis in the elderly include:²

• Otitis media
• Sinusitis
• Pneumonia
• Apnea
• Insomnia
• Urinary incontinence
• Rib fracture
• Weight loss
• Migraines
• Carotid artery dissection
• Fainting after cough

The complication of hospitalisation is higher in older patients. A study showed hospitalisation rates of 12% in patients with pertussis over 65 years old.⁷

Luckily, deaths are rare, and these cases are often linked to comorbid diseases,¹ meaning that pertussis could also cause a deterioration of comorbid conditions.

Prevention strategies for pertussis in the elderly

It is possible to prevent pertussis with vaccination and, if needed, prophylactic antibiotic therapy after contact with confirmed cases (post-exposition prophylaxis).

The pertussis vaccination and past infection with pertussis do not ensure lifelong immunity. Pertussis booster vaccinations are necessary to ensure ongoing protection. A booster vaccination is recommended in adults and the elderly, especially those with chronic conditions, with the aim of preventing and reducing the disease burden in infected people and reducing the incidence of pertussis, especially in neonates, due to herd immunity. Some countries (France, Austria, USA, Canada, and Australia) have implemented this evidence and recommended that their elderly population undergo a pertussis booster as part of their vaccination programme.^3,9

Herd immunity is essential for all individuals unable to get the vaccine themselves, such as neonates or people with contraindications for vaccinations, such as certain allergies. It is known that neonates get infected with Bordetella pertussis mainly through infected adults and adolescents. The reason is that the adults have mostly unspecific symptoms with late diagnosis and treatment.¹⁰ Therefore, older people in close contact with newborns (such as grandparents) are also recommended a booster vaccination.¹

Treatment and management of pertussis in the elderly

Besides symptomatic therapy, the specific treatment of pertussis is an antibiotic therapy with macrolides to reduce the severity, duration and transmission. Treatment is most effective in the first three weeks during the catarrhal stage. Since the symptoms are unspecific, the disease is often recognised later, and the treatment is implemented in the most effective timeframe.¹ Further therapy or hospitalisation can be necessary, depending on the complications mentioned above.

Summary

Older people are affected by pertussis in lower numbers than children. However, due to their role in transmitting the disease and their susceptibility to complications, especially in comorbid patients, education about pertussis in older people is important. To reduce overall transmission rates and lower the disease burden of the elderly, early recognition of pertussis in the older age groups is important. However, this remains difficult since the symptoms in this age group are unspecific and sometimes only present with coughing. To prevent this illness, the elderly should consider taking a booster vaccine for pertussis, on the one hand, to protect themselves, but also to protect others, especially newborns.