Causes and How It Spreads

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Whooping cough is a very contagious respiratory illness that spreads from person to person.


Whooping cough, also known as pertussis, is a very contagious respiratory illness caused by a type of bacteria called Bordetella pertussis. The disease is only found in humans.

Whooping cough bacteria attach to the cilia (tiny, hair-like extensions) that line part of the upper respiratory system. The bacteria release toxins (poisons), which damage the cilia and cause airways to swell.

How it spreads

Mother and her newborn baby at home.

Babies can get whooping cough from family or caregivers who don’t know they have it.

The bacteria that cause whooping cough spread easily from person to person through the air. When a person who has whooping cough sneezes or coughs, they can release small particles with the bacteria in them. Other people then breathe in the bacteria. It also spreads when people spend a lot of time together or share breathing space, like when you hold a newborn on your chest.

People can be contagious for weeks

People can spread the bacteria from the start of the very first symptoms and for at least 2 weeks after coughing begins.

Taking antibiotics early in the illness may shorten the amount of time someone is contagious. Learn more about treatment.

People can spread the disease even if they don’t know they have it

Some people have mild symptoms and don’t know they have whooping cough, but they can still spread the bacteria to others.

Many babies who get whooping cough are infected by older siblings, parents, or caregivers who don’t know they have it. Learn what you can do to protect babies from whooping cough.