pertussis

Pertussis, better known as whooping cough, is a bacterial infection famous for its violent coughing fits. A child coughs over and over in a single breath until the lungs are emptied, then drags air back in through a narrowed throat with a high-pitched whoop. The fits come in waves, can end in vomiting or exhaustion, and may drag on for weeks — which is why it earned the nickname the hundred-day cough.

It is caused by the bacterium Bordetella pertussis, which attaches to the lining of the airways, paralyzes the tiny clearance hairs and releases toxins that drive the inflammation and the characteristic spasmodic cough. The illness begins deceptively like a common cold for a week or two, then enters the paroxysmal phase of severe coughing fits before slowly fading. In young infants the whoop may be absent and the danger instead shows as pauses in breathing.

Antibiotics, especially macrolides, can reduce spread and help if given early, but once the violent coughing is established they do little to shorten it, so much of the care is supportive. The infection is most dangerous in young babies, who can suffer pneumonia, breathing pauses or seizures, which is why vaccination in childhood — and a booster in pregnancy to protect the newborn — is so important.

Immunity from both vaccination and natural infection wanes over years, so older children and adults can catch pertussis again, often as a prolonged nagging cough that is easily mistaken for an ordinary chest infection and can unknowingly spread to vulnerable infants.