Recommended case classifications of pertussis
Clinically-confirmed
A clinically-confirmed case is diagnosed as pertussis by a physician of a person with a cough lasting at least two weeks with at least one of the following symptoms: paroxysms (i.e. fits) of coughing; inspiratory whooping; post-tussive vomiting (i.e. vomiting immediately after coughing) without another apparent cause. The case is not laboratory-confirmed.
Laboratory-confirmed
A laboratory-confirmed case meets the clinical case definition and is laboratory-confirmed by isolation of Bordetella pertussis or detection of genomic sequences by means of the polymerase chain reaction (PCR) or positive paired serology.
Laboratory confirmation is not readily available in most countries. Therefore, disease surveillance is based mainly on clinical diagnosis of cases. Monitoring the number of infants who have received the third dose of diphtheria toxoid-containing vaccine (DPT3) is important.
Surveillance of pertussis consists of a routine monthly report of aggregated data on clinical cases in countries with DPT3 coverage less than 90%. Reported data should be stratified by age. In countries with DPT3 coverage equal to or higher than 90%, case-based surveillance is recommended. Immediate investigation of all pertussis outbreaks with collection of case-based data is also recommended. In addition, sentinel surveillance is recommended in a few major hospitals to collect more in-depth information than that obtained through routine surveillance.