Polymerase chain reaction (PCR)is the preferred test
Good Practice TipDuring the consultation and especially during the physical examination consider wearing a surgical mask to protect yourself from exhaled infective droplets. Be especially careful when examining the patient's mouth as you are directly in the firing line!Serology for Bordetella pertussis
PCR is useful for diagnosis early in the course of the disease. It is more sensitive than culture, and may remain positive for a longer period (up to 4 to 5 weeks) after the onset of symptoms and for some time after starting treatment.
- The test can be performed on throat swabs, nasopharyngeal swabs or nasopharyngeal aspirates.
- Use dry DacronTM or rayon tipped swabs on flexible metal or (preferably) plastic sticks. Wooden swabs and calcium alginate tips are unsuitable for PCR. Swabs should be sent to the laboratory dry (do not place in transport medium).
Pertussis serology provides suggestive evidence of infection when there is a compatible clinical presentation and no history of recent pertussis vaccination. Positive result is indicated by any of the following:
Good Practice Tip
- Seroconversion or a fourfold or greater rise in Bordetella pertussis titre
- A single high IgA titre to whole Bordetella pertussis cells
- Detection of B. pertussis antigen by immunofluorescence assay (IFA).
Serology is not as useful for detecting early infection as PCR. By using PCR to detect earlier cases, you have more opportunity to treat infectious patients and prevent them transmitting infection to others.