Pertussis (whooping cough)

Pertussis, also known as whooping cough, is a bacterial infection that affects breathing and can be prevented with vaccination.

Pertussis can be a very serious illness in babies. Babies under three months or older babies with difficulty breathing, eating or drinking may need to be admitted to hospital to support their breathing and nutrition.

Signs and symptoms of pertussis

Common symptoms include:

• persistent, severe coughing that occurs in clusters
• a cough followed by vomiting of milk, food or mucus
• a change in the colour of the face when coughing
• a high-pitched whoop sound when breathing in.

Symptoms start seven to 14 days after a child is exposed to the infection.

What does a pertussis cough sound like?

The classic sound of whooping cough occurs in the second phase of the illness. Click on this link from the Merck Manual website to hear what it sounds like:

• Classic sound of whooping cough

Some children and adults with pertussis may have a cough that is milder. They can still spread the illness and infect others.

Cause of pertussis

This illness is caused by the bacteria (germ) Bordetella pertussis.

Phases of pertussis

The illness has three phases.

First phase

During this phase, your child will begin to have cold-like symptoms, such as mild fever, a runny nose and cough. These symptoms last for about two weeks and are similar to those of many viral upper respiratory tract infections.

Second phase

In this phase, the cough gets worse, and infants are at highest risk of breathing problems. Your child may have severe coughing episodes. These are sudden short, fast coughs that occur in clusters.

Coughing makes breathing difficult.

When your child takes a breath in after a cluster of coughs, you will hear a high-pitched whooping sound. Children less than six months old typically do not whoop and may instead gasp or gag during coughing episodes. Infants and young babies often hold their breath after coughing, and their oxygen levels and heart rate can drop. Young infants with pertussis need close monitoring in hospital. It may take several weeks until they improve.

The coughing may also cause your child to vomit milk, food or mucus.

Your child will also often turn red in the face from coughing but will look relatively well between coughing episodes.

This phase lasts for two to eight weeks.

Third phase

This phase includes healing and recovery. Your child will continue to have a persistent cough, but it will be less severe than in the second phase. This phase can last from weeks to months.

How pertussis is diagnosed

If the doctor thinks your child has pertussis, they will take a swab of the secretions (mucus) from your child's nose for testing.

How pertussis is treated

Your child will need to take antibiotics to fight the bacteria that cause pertussis. The antibiotics are most effective at reducing symptoms if started early at the start of illness. Antibiotics can also reduce the ability of children with pertussis to infect others.

Make sure your child completes the full course of antibiotics, even if their symptoms seem to improve. People in close contact with your child may be asked to take an antibiotic so the infection does not spread.

How can you prevent pertussis?

You can prevent pertussis by having your child vaccinated.

If you or your child has been vaccinated, the immunity (protection) offered by the vaccine can decrease over time. This is why it is important to be up to date on vaccines and get boosters when indicated. Adolescents and adults who do not get a booster vaccine can become infected and pass the infection to children. Babies who have not received their complete vaccination for pertussis are also at risk for getting the infection. They can get sick very quickly when exposed to others who have it. Vaccination of pregnant women in the last trimester of every pregnancy is especially important since it protects infants who are too young for vaccination and are at high risk of severe pertussis infection.

Complications of pertussis

Pertussis can be harmful, especially for babies. Complications may include pneumonia, apnea (breaks in breathing), seizures and even death.

Caring for your child at home

Use a humidifier

Humid air may help loosen mucus, while dry air tends to make coughs worse. A cool mist vaporizer or humidifier in your child's bedroom may help. Change the water and clean any filters at least once a day.

Remove mucus with saline solution

Use a nasal saline solution and nasal suction to help remove mucus in the nose and throat.

Adjust your child's sleeping position

Keep your child upright before and after feeding to reduce spitting up and vomiting. This position also makes breathing easier.

Offer small amounts of fluid often

Encourage your child to drink small amounts of fluids often. It is important to maintain hydration if your child is vomiting. Breastfed babies should continue breastfeeding.

Avoid smoky places

Keep your child away from smoke and other environmental irritants. Cigarette smoke can make coughs worse.

When to see a health-care provider

Call your child's health-care provider if:

• your child's cough is persistent, getting worse or occurring in clusters
• your child has had contact with someone who has pertussis.

Go to your nearest Emergency Department or call 911 if:

• coughing causes your child's face to turn blue or your child to stop breathing
• coughing makes breathing difficult or fast
• your child is not responding to you or seems lethargic (sluggish)
• your child has a seizure (persistent shaking of the body that cannot be stopped)
• your child is vomiting or not drinking and is getting dehydrated.

Your child may show physical changes when their condition is serious or when their condition gets worse. Parents and caregivers can learn how to spot these signs in order to seek help from a health-care provider.

Find information about immunization schedules for each province and territory
Health Canada (July 2020). Provincial and Territorial Immunization Information. Retrieved from https://www.canada.ca/en/public-health/services/provincial-territorial-immunization-information.html

Health Canada (March 2024). Pertussis (whooping cough): For health professionals. Retrieved from https://www.canada.ca/en/public-health/services/immunization/vaccine-preventable-diseases/pertussis-whooping-cough/health-professionals.html

Merck Manual (June 2024). Whooping cough (classic whoop). Retrieved from https://www.merckmanuals.com/en-ca/professional/multimedia/audio/whooping_cough_classic_whoop