Whooping cough, or pertussis, is an acute infectious disease that is a leading cause of death in infants unprotected by immunization. The infective agent, the bacterium Bordetella pertussis, is transmitted by inhalation of material expelled by the coughing of infected patients. After an incubation period of about a week, symptoms at first resemble those of the common cold; after 7 to 10 days, coughing increases and becomes distinctive. A series of short coughs of increasing intensity is followed by a long indrawing of breath with the characteristic crowing sound or "whoop." The patient's face often becomes blue during the frightening spasms; clear sticky mucus is expelled, and vomiting commonly occurs. Pneumonia is a dangerous complication. The younger the patient, the greater the risk of serious illness; most deaths from whooping cough occur in the first 6 months of life.
Treatment includes careful nursing, sedatives, and plenty of fluids. Antibiotics are needed only for the treatment of complications, such as pneumonia. Prevention is by immunization with a vaccine containing killed pertussis bacteria, often given in combination with diphtheria and tetanus vaccines.