What Are The Symptoms Of Pertussis In Newborns?

What is pertussis (whooping cough)?

Pertussis, commonly known as whooping cough, is a highly contagious infectious disease caused by the bacterium Bordetella pertussis. The most common and noticeable symptom is a persistent cough that can last for several weeks or months.¹ Pertussis has the name whooping cough due to sufferers' distinctive “whooping” sound as they gasp for breath after a coughing fit. 

Whilst pertussis can and does affect adults, the incidence rate and severity of symptoms are much greater in infants under 12 months old, and especially in newborns.² Newborns are most at risk of developing additional complications, such as pneumonia, pulmonary hypertension, and seizures, which can be life-threatening. 

Fortunately, in the developed world, vaccination programmes to protect against catching pertussis are well-established and yet it remains one of the most common vaccine-preventable diseases.³ This is partly due to gaps in scientific knowledge about disease transmission, but also due to widespread misconceptions about vaccination. This article serves to demystify pertussis so you can make informed decisions to protect yourself and the most vulnerable of those in the world, the newborns.

What causes pertussis?

Pertussis is caused by the bacterium Bordetella pertussis (B. pertussis), which is spread through the airborne particles released when an infected person coughs or sneezes. These particles can then be inhaled by an uninfected person. B. pertussis is highly contagious for at least 2 weeks after symptoms begin, allowing infection to spread rapidly.⁴ The risk of transmission is greatest during the summer when reported pertussis infection rates peak seasonally.⁵

The precise pathogenesis of pertussis, which refers to the biological mechanisms that cause the disease, is not fully understood by scientists. However, it is known that B. pertussis enters the upper respiratory tract when inhaled and attaches itself to ciliated cells (cells covered in microscopic hairs) that line the tract.

Once attached, the bacteria release toxins that interfere with the normal process of clearing germs from the airways, allowing the bacteria to proliferate and spread throughout the respiratory tract. These toxins also damage the respiratory cells, resulting in inflammation and swelling of the airways, thus reducing the person’s ability to breathe properly and instigating the symptomatic “whooping” cough. 

How do newborns catch pertussis?

Among infants less than 12 months old, newborns have the highest incidence rate of pertussis.⁵ Newborns do not have a fully developed immune system (which is chiefly established throughout the first 100 days of life) and therefore are highly susceptible to infections.⁶

Newborns rely primarily on maternal antibodies, received during the gestation period, to protect themselves against infection – however, this may not be enough to resist the highly contagious B. pertussis bacterium.⁷

Newborns are exposed to B. pertussis from parents, siblings, and caregivers who are unknowingly infected (and may not have any symptoms), even without physical contact. Family members of any age account for nearly 50% of pertussis transmissions to newborns.^8,9

What are the symptoms of pertussis?

Pertussis symptoms go through three phases:

• Phase 1 (up to 1 week): A mild, dry cough that lasts for a few days. At this stage, it is difficult to distinguish the infection from various other minor respiratory tract infections, which all present with broadly similar symptoms
• Phase 2 (2–6 weeks): The cough becomes more regular and severe, and often occurs as a paroxysm (sudden attack). The “whoop” sound is made as the sufferer attempts to take in air after an attack through their narrowed (swollen) airway
• Phase 3 (2 weeks–months): The cough becomes milder again as the person recovers. Full recovery can take several months, and symptoms will likely persist long after a person is no longer contagious

It is worth noting that fever is not a symptom of pertussis.^2,9

Pertussis complications in newborns

Despite the name whooping cough, newborns with pertussis may not present coughing or “whooping” symptoms at all.² This makes correct diagnosis of the infection during the crucial early stages a challenge and should serve to emphasise the importance of seeking urgent medical attention if your newborn presents with pertussis symptoms.

Clinical complications arise in newborns as they enter phase 2 of the infection (even without the cough). Apnoea (temporarily not breathing during sleep) is a tell-tale symptom of pertussis, and although it is frightening to witness it cannot directly cause death. The reduced air intake (from apnoea or coughing paroxysms) can cause another complication called cyanosis where the skin turns blue from insufficient oxygen levels. Cyanosis is not serious by itself but is a strong indicator of pertussis and should be acted upon immediately.

Severe, potentially life-threatening complications can arise rapidly from pertussis in newborns, and immediate hospital treatment is needed in these instances. These complications often involve the pulmonary (respiratory) system or the central nervous system (brain and spinal cord). Pneumonia, an infection of the lungs, is the most common cause of death in infants with pertussis. Pulmonary hypertension, high blood pressure in the lungs, is also a mortality factor. Seizures, from reduced oxygen levels in the central nervous system, are another serious complication.¹⁰

Pertussis complications in newborns/infants include the following (non-exhaustive list):

• Apnoea – temporary cessation of breathing during sleep
• Cyanosis – skin turning blue
• Vomiting, sometimes with thick mucus
• Dehydration
• Weight loss
• Bronchitis
• Ear infection
• Hernia
• Seizures (severe)
• Pneumonia (severe)
• Pulmonary hypertension (severe) – high blood pressure in the lungs
• Encephalopathy (severe) – brain dysfunction
• Meningoencephalitis (severe) – infection and inflammation of the brain

Treatment of pertussis

For adults and children over 6 months old with mild pertussis, treatment at home mostly involves rest and drinking plenty of fluids. Paracetamol and ibuprofen can be taken if the recipient is old enough. As pertussis is highly contagious, it is recommended to avoid contact with the sufferer as much as possible for ~2 weeks following the onset of symptoms.

Prescribed antibiotics are especially effective in eliminating a B. pertussis infection (even though symptoms may persist), and if started within 3 weeks of infection these are the biggest preventative measure of death in infants.¹⁰ 

Hospital treatment of newborns with pertussis

Upon hospitalisation, doctors will perform a diagnostic test with a swab of blood from the newborn to get a definitive diagnosis of pertussis and measure their levels of white blood cells (immune cells). Treatment begins immediately before the results of these tests are returned. 

The main hospital treatment for pertussis is intubation (inserting a tube into the airway through the mouth), which allows for assisted ventilation and oxygen administration. Exchange blood transfusion (replacing the newborn’s blood with that of a donor) may also be performed, which helps to reduce toxins in the blood and bring escalating white blood cell levels down to a more normal level. The doctors will also give the newborn antibiotics.¹⁰

Vaccination – the best way to prevent pertussis

Vaccination works by allowing the body’s immune system to generate protective antibodies in the blood against a specific pathogen (germ), with minimal or zero risk of developing the infection itself. These antibodies have “memory” properties and persist for years, primed to eliminate the pathogen if it enters your body. There are many different types of vaccinations, and their suitability depends on the infection they prevent, the age of the recipient, their medical conditions/medication and whether they are immunocompromised. Different countries have different vaccination schedules too.

Vaccination is the best way to prevent pertussis and minimise symptom severity in adults/children/infants of any age.¹¹ Newborns under 2 months old are too young to receive a direct vaccine, which makes vaccination of the pregnant mother during the second or third trimester even more important. This allows the mother to generate protective antibodies against B. pertussis which are transferred to the foetus during gestation.

DTaP and Tdap Vaccines

The two vaccines against pertussis are called “DTaP” (Diphtheria, Tetanus, and acellular Pertussis), given to infants and young children, and “Tdap” (Tetanus, Diphtheria, and Pertussis), given to pregnant women, and suitable for older children, and adults.

The precise pertussis vaccination schedule differs from country to country. If you live in the UK, please refer to the NHS website for up-to-date DTaP and Tdap schedules (DTaP is part of the “6-in-1 vaccine”). Currently, the recommended schedule is:

DTaP (for infants and young children) doses

• 1^st dose: 8 weeks old
• 2^nd dose: 12 weeks old
• 3^rd dose: 16 weeks old
• Booster: 40 months old

Tdap (for pregnant women)

• Only dose: Ideally given at any time between 16–32 weeks of pregnancy, but it can be given right up until labour

In a study of over 20,000 pregnant women who received the Tdap vaccine, there was zero evidence to suggest that the vaccine is unsafe for pregnant women or their babies. The DTaP and Tdap vaccines are strongly recommended for everybody.¹² 

Summary

Pertussis, also known as whooping cough, is a highly contagious infectious disease that poses a significant risk of death to newborns. Whilst the disease is known for its distinctive “whooping” sound caused by the intake of breath after a coughing attack, newborns may not present with this symptom. Other key signs of pertussis to look out for are apnoea (not breathing during sleep) and cyanosis (skin turning blue). Severe complications can also arise, such as pneumonia and seizures.

Antibiotics are the main treatment for pertussis, and hospitals may also administer assisted ventilation, oxygen, and/or a blood transfusion depending on the circumstances. Receiving a pertussis vaccine during pregnancy is the most effective method to protect newborns from pertussis, and is entirely safe. Awareness of the symptoms of pertussis in newborns is vital because urgent medical attention is required if they occur.