What is Whooping Cough?
Whooping cough, also known as pertussis, is a contagious infection of the respiratory tract. While most respiratory tract infections are due to viruses (example : common cold, influenza), pertussis is caused by bacteria, namely the Bordetella pertussis bacterium.
Pertussis typically affects the upper respiratory tract but can spread throughout entire respiratory system and result in conditions like pneumonia. Unlike many other infections, you will not be immune to pertussis even if you had it earlier in life or had the vaccine more than 3 to 5 years ago.
Outbreaks of pertussis are not uncommon and children are more at risk of contracting the infection. However, a triple vaccination against pertussis, which is given to children older than 6 months, has drastically reduced outbreaks. Adults may also be prone to acquiring pertussis, especially if they have a child with the infection, or work closely with children – teachers, baby sitters, day care providers as well as medical workers. In the event of an outbreak, adults with children who may be at risk of contracting pertussis should consider booster vaccinations.
Causes and Spread of Whooping Cough
Pertussis is caused by the Bordetella pertussis bacteria. It is transmitted from person to person via droplet spread. Microscopic droplets of saliva or mucus spread through the air during coughing, sneezing or spitting and any person in close contact with an infected individual can contract the infection.
The bacteria attach to the minute hairs lining the upper respiratory tract known as the cilia. These cilia trap dust and microorganisms that may enter the respiratory tract. The pertussis bacteria releases toxins which damages these cilia and causes inflammation of the surrounding area (ciliated respiratory epithelium).
While any person can contract pertussis, childhood vaccination programs have reduced the incidence of the disease. However, children older than 11 years and adults are still prone to contracting the infection if they are exposed to infected individuals and have not had booster vaccine shots. The highest risk group are infants younger than 6 months old as they are not fully vaccinated as yet and may contract the infection from others who come in close contact with them.
Since a person with pertussis can be contagious for 6 to 8 weeks, the chances of transmitting the infection to others is therefore prolonged compared to other common respiratory infections. In addition, pertussis is often misdiagnosed as the common cold or influenza and treatment is not sought at an early stage thereby increasing the chances of transmitting the infection to others.
Signs and Symptoms of Different Stages of Whooping Cough
The incubation period of pertussis ranges from 3 to 12 days. Symptoms are usually evident 7 to 10 days after contracting the infection and the disease can last for a minimum of 6 weeks. It may extend for up to 8 to 12 weeks. The three stages of pertussis are as follows :
Stage 1 – Catarrhal Phase
This is the most contagious period and contagiousness may extend for up to 2 weeks after the onset of a cough. The symptoms in this stage appear similar to most common respiratory tract infections, like the common cold and influenza, and is therefore misdiagnosed or ignored initially. These symptoms include :
- Runny nose (rhinorrhea)
- Nasal congestion
- Watery eyes (tearing)
- Low grade fever (may be absent)
- Minor cough – mild, occasional coughing
Stage 1 of the infection may last for 1 to 2 weeks.
Stage 2 – Paroxysmal Phase
The symptoms are more severe in this stage of pertussis and are characteristic of whooping cough. Most of the nasal symptoms ease at this point but the cough becomes severe. Symptoms of stage 2 include :
- Uncontrollable fits of coughing
- These attacks (paroxysms) may be so severe that a person turns red in the face (flushing).
- In infants younger than 6 months, paroxysmal coughing may not be present but instead the baby may have episodes of apnea, where they stop breathing.
- Breathing may be difficult due to the coughing fit and inhaling deeply in between causes the typical ‘whooping’ sound.
- Whooping Cough Audio. Listen to the typical pertussis cough sound on PKids.org
- This tends to occur after a severe fit of coughing.
- This is a result of coughing fits and limited oxygen intake during these periods.
- A person may feel well and energetic in between coughing fits.
Stage 2 of pertussis may last for 2 to 3 weeks but can extend for as long as 10 weeks (“100 day cough”).
Stage 3 – Convalescent Phase
A chronic cough develops in this stage that is not as severe as in stage 2. It can last for weeks or sometimes even months especially if it is complicated with other infections like colds and the flu. The coughing fits may become louder but are infrequent in that it stops for a few days and then begins again for a few more days.
Whooping Cough Vaccine and Immunization
Pertussis can be prevented if a person immunized at an early stage. This does not guarantee immunity against pertussis, however, if you do contract the infection after being appropriately immunized, the symptoms are usually milder and recovery is quicker.
The most common vaccines for pertussis immunization are the DTaP and Tdap vaccines. These vaccines are so named because they also offer protection for diptheria (d or D) and and tetaus (t ot T).
The pertussis component (p or P) is needed in full-strength doses (P) in children younger than 7 years of age. This is usually administered at 2, 4 and 6 months or age, as well as at ages of 15 to 18 months and again at 4 to 6 years. Proper immunization usually offers a child protection up to the age of 11 to 12 years.
Children of 12 years of age or older as well as adults will need booster shots (Tdap).