Pertussis, also known as whooping cough, is a highly infectious disease caused by the bacterium Bordetella pertussis. It is usually transmitted via the respiratory route and starts with non-specific catarrhal (‘common cold’) symptoms. Typically, an intermittent uncontrollable cough then develops, causing spasms. Coughing fits, may end with an inspiratory whoop and vomiting. Young infants do not always develop a ‘whoop’ following the coughing spasms, but may instead experience difficulty breathing or even stop breathing for a short time.

Symptoms are worse at night and the illness can last for two to three months. Infants under six months are at highest risk of severe complications and death from pertussis. Milder symptoms may be observed in older children and adults who have previously been vaccinated.