A clinically compatible case characterised by cough and one or more of:

• paroxysms of cough
• cough ending in vomiting, cyanosis or apnoea
• inspiratory whoop.

Infants are less likely to have the inspiratory whoop and are more likely to present with gagging, gasping, cyanosis, apnoea, or non-specific signs such as poor feeding or seizures.

Adults and children partially protected by vaccination can present with illness ranging from a mild cough illness to classic pertussis.