The Gold Coast Public Health Unit advises that there has been a resurgence of pertussis in our community recently. This has mostly been in school aged children, but there have been cases where vulnerable infants under six months of age have been affected.
They remind clinicians that pertussis PCR should be considered the diagnostic method of choice. Serological testing may be considered if the presentation is delayed until after 4 weeks from any cough onset, or more than 3 weeks after commencement of paroxysmal cough. However, PCR can still be positive for five weeks or longer.
Nasopharyngeal aspirates or nasopharyngeal swabs with Dacron™ or rayon tipped swabs are optimal and calcium alginate swabs should not be used. Throat swabs may also be used, although they suffer from lower sensitivity. Swabs for PCR should be sent to the laboratory dry – not in transport medium.
Pertussis is a prolonged coughing illness with clinical manifestations that vary by age. An initial catarrhal phase is characterised by the insidious onset of runny nose, sneezing, absent or low-grade fever, and a mild occasional cough.
The cough gradually becomes paroxysmal (after 1–2 weeks), and may end in vomiting, cyanosis and/or a characteristic high-pitched inspiratory ‘whoop’.
Paroxysms may recur with subsequent respiratory illnesses for many months after the onset of pertussis. Fever is generally minimal throughout the course of the illness and subclinical infections may occur.
Infants are less likely to have the inspiratory whoop and a significant catarrhal stage 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, though this may be without the inspiratory whoop. In adults, post-tussive vomiting (when present) is strongly suggestive of pertussis.
The GCPHU will contact the requesting clinician upon notification of a confirmed (PCR detected) case of pertussis. This is to reduce the risk of ongoing transmission of pertussis, particularly to infants under six months of age.