What are the key clinical features to consider when diagnosing whooping cough in a child?

Key clinical features to consider when diagnosing whooping cough (pertussis) in a child include:

• A prolonged cough lasting two weeks or more, often paroxysmal (sudden, intense coughing fits) in nature, which is a hallmark of the disease NICE NG9.
• The characteristic inspiratory 'whoop' sound following coughing fits, especially in older infants and children, though it may be absent in very young infants NICE NG9.
• Post-tussive vomiting, where vomiting occurs immediately after coughing episodes, is a common associated symptom NICE NG9.
• Apnoeic episodes (pauses in breathing) are particularly important to note in infants and young children, as they may be a presenting feature NICE NG9.
• Absence of fever or only low-grade fever during the illness, which helps differentiate pertussis from other respiratory infections NICE NG9.
• History of exposure to a confirmed or suspected case of pertussis or incomplete vaccination status should raise clinical suspicion Tan et al. 2005.
• In the early catarrhal phase, symptoms may resemble a common cold with mild cough and coryza, making early diagnosis challenging Tan et al. 2005.

Overall, the diagnosis is primarily clinical, based on the characteristic cough pattern and associated features, supported by epidemiological context and vaccination history NICE NG9 Tan et al. 2005.