Whooping Cough (Pertussis)

How whooping cough spreads

Pertussis bacteria attach to the lining of the airways and release toxins that damage the lining and cause swelling. It spreads through droplets when an infected person coughs or sneezes. It is extremely contagious: most unvaccinated household contacts will catch it. People are most contagious in the early, cold-like stage, before whooping cough is suspected. Without treatment, they can spread it for up to about 3 weeks after coughing starts.

Babies often catch it from older siblings, parents or caregivers who have mild symptoms or do not realize they have it.

Symptoms by stage

Stage 1: catarrhal (1 to 2 weeks)

• Runny nose and sneezing
• Low-grade fever
• Mild, occasional cough

Stage 2: paroxysmal (1 to 6 weeks, sometimes up to 10)

• Fits (paroxysms) of many rapid coughs in a row
• A high-pitched "whoop" when breathing in after a fit
• Vomiting after coughing
• Exhaustion after fits
• Red or blue face during fits
• Feeling relatively well between fits
• Fits often worse at night

Stage 3: convalescent (weeks to months)

• Gradual recovery, with fewer and milder fits
• Coughing can return with later colds

Whooping cough in babies

Babies may not cough much or whoop, and early symptoms can look like other infant infections such as RSV bronchiolitis. Instead, they may:

• have pauses in breathing (apnea)
• turn blue or gray
• struggle to feed
• gag or gasp

About a third or more of babies under 1 who get whooping cough need hospital care. Complications include pneumonia, seizures, brain damage and death, mostly in the youngest infants.

Whooping cough in adults and teens

Symptoms are often milder, mainly a prolonged cough without a whoop, so it is often mistaken for acute bronchitis or asthma. Complications include rib fractures from coughing, hernias, broken blood vessels in the eyes, urinary incontinence, poor sleep and weight loss. The main risk is spreading it to babies.

Diagnosis

• Nose and throat swab for PCR testing, most accurate in the first 3 weeks of cough
• Culture, the traditional test, more specific but slower
• Blood tests for antibodies later in the illness
• Chest X-ray if pneumonia is suspected
• In young children, doctors also consider croup, which causes a barking cough and noisy breathing in, rather than coughing fits

Doctors often start antibiotics based on symptoms and exposure, especially for babies or people in contact with babies.

Treatment

• Antibiotics: azithromycin is usually used. Clarithromycin or trimethoprim-sulfamethoxazole are alternatives in some cases. Antibiotics started early may lessen symptoms, and at any stage they reduce spread. People are generally considered no longer contagious after 5 days of appropriate antibiotics.
• Hospital care for babies: monitoring, suctioning, oxygen, help with feeding and fluids.
• Supportive care: rest, fluids, small frequent meals, a humidifier, avoiding smoke and other irritants. Cough medicines do not help pertussis fits.
• Preventive antibiotics for close contacts, especially households with babies or pregnant people.
• Stay home from school, work or childcare until 5 days of antibiotics have been completed.

Complications

• Pneumonia
• In babies: apnea, seizures, brain damage, dehydration, weight loss, death
• In older children and adults: rib fractures, fainting, hernias, broken blood vessels in the eyes, sleep loss

Prevention

• DTaP for children at 2, 4, 6 and 15 to 18 months, and 4 to 6 years
• Tdap booster at 11 to 12 years
• Tdap during every pregnancy, ideally early in the 27 to 36 week window. Antibodies pass to the baby and protect them in the first months before they can be vaccinated
• Adults who have never had Tdap should get one dose, especially those around babies
• Cover coughs and sneezes and wash hands

Protection from vaccines fades over time, so vaccinated people can still get pertussis, usually more mildly.

Frequently asked questions

What are the symptoms of whooping cough?

It starts like a cold with a runny nose, mild cough and low fever. After 1 to 2 weeks, violent coughing fits develop, often followed by a whoop, vomiting or exhaustion. Babies may not whoop but may stop breathing or turn blue, which is an emergency.

How long is whooping cough contagious?

People are most contagious in the first 1 to 2 weeks, during the cold-like stage. Without treatment, they can spread it for up to about 3 weeks after coughing begins. After 5 days of appropriate antibiotics, they are usually no longer contagious.

Can adults get whooping cough?

Yes. Immunity from childhood vaccines and past infection fades, so adults and teens can get whooping cough. It often causes a long-lasting cough without a whoop. Adults can spread it to babies, so a Tdap booster is recommended, especially for anyone around infants.

Why do pregnant people get the Tdap vaccine?

Getting Tdap during pregnancy, ideally between 27 and 36 weeks, lets the mother's antibodies pass to the baby. This protects newborns during their first months, when whooping cough is most dangerous and before they can complete their own vaccines.

How long does whooping cough last?

Whooping cough can last 10 weeks or more, which is why it is called the 100-day cough. The cold-like stage lasts 1 to 2 weeks, coughing fits last several weeks, and recovery with a fading cough can take weeks to months.