Sensitivity and specificity of the World Health Organization pertussis clinical case definition

Abstract

Bordetella pertussis continues to circulate even in countries with good childhood vaccination coverage. This study was undertaken to define the relationship between documented disease and the clinical criteria proposed by the World Health Organization (WHO). Nasopharyngeal swab samples were collected from previously healthy 6-14-year-old school children in Tehran, presenting with persistent cough of at least 2- week duration. Specimens were examined for Bordetella pertussis and Bordetella parapertussis by culture and polymerase chain reaction (PCR). Out of 6601 students, 328 (5.0%) had been coughing for at least 2 weeks. Of these children with cough, 182 (55.5%) experienced whooping, 194 (59.1%) suffered a paroxysmal cough, and 73 (22.3%) had post-tussive vomiting. Twenty-one (6.4%) samples tested positive for B. pertussis and six (1.8%) for B. parapertussis by PCR. Culture of four (1.2%) specimens was positive for B. pertussis. In comparison to PCR, the sensitivity and the specificity of the WHO clinical criteria (year 2000) were 95.2% and 15.0%, respectively. Pertussis remains one of the etiologies of prolonged cough, even in communities with high immunization in children. The specificity of the WHO criteria is low in diagnosing pertussis compared with PCR.