Pertussis, commonly known as whooping cough, is a bacterial infection caused by the bacterium Bordetella pertussis.

Pertussis is highly contagious and circulates all year long. Pertussis is transmitted from person to person through coughing and direct contact with the mucus of a person who is actively contagious.

The major symptom of pertussis is uncontrollable coughing. Infants younger than three months are at highest risk of complications because their lungs are still developing.

For most, whooping cough is a relatively mild illness, and recovery provides lifelong immunity.