Infection: Pertussis; whooping cough, Bordetella pertussis infection
- Highly infectious respiratory infection. Epidemics occur around every 3-5 years.
- Can cause severe disease in infants <6 months old or children with chronic cardiac or respiratory illness.
- In the early stages resembles a viral URTI, which precedes the development of the typical coughing episodes.
- People are regarded as infectious for 21 days from onset of cough.
Did you know?
Antibiotic therapy is recommended within the first three weeks of symptoms, mostly to reduce the period of infectivity. It may alter the natural course of the illness if given within the first week, but not if given after that.
Who should I test?
Testing is recommended in those with symptoms consistent with pertussis who have been unwell for <4 weeks. Beyond this time the sensitivity of the test is poor and is not recommended.
Test of choice:
Request Pertussis PCR
PCR on nasopharyngeal swab
- Uncertain sensitivity – a negative result doesn’t exclude infection, especially if there is a high degree of clinical suspicion. Sensitivity is highest early on in infection.
- Good specificity – a positive result makes the diagnosis highly likely in someone with a compatible illness. Occasionally, other Bordetella species can cause positive results.
Tests to avoid/specialist tests:
- We do not recommend serology for pertussis, as interpretation of results can be confounded by prior vaccination or infection.
- The positive predictive value of a positive serology test in a patient with a chronic cough is generally not high enough to exclude other more important causes.
Suspected pertussis infection should be notified immediately to Public Health.