ABSTRACT
ObjectiveTo characterize the incidence of laboratory confirmed pertussis cases by immunization status in Ninghai County， and to provide evidence for improving pertussis prevention and control strategy in Ninghai County. MethodsData of reported pertussis cases in Ninghai County from 2018 to 2019 were collected through the National Notifiable Infectious Disease Reporting System. The immunization history of vaccines related to pertussis was collected through the Ningbo Immunization Planning Information Management System and field investigation. Descriptive epidemiological methods were used to analyze the collected data. ResultsThe respiratory secretions collected in the 64 cases tested positive for nucleic acid of Bordetella pertussis bacilli， of which 56.25% aged 0‒1 year. They were mainly pre-school children. No adolescent or adult case was reported. All cases had whooping cough. Of the cases， 78.13% had an increase in white blood cell count， 62.5% had an increase in lymphocyte percentage， 59.38% had completed three or more doses of pertussis vaccination， 69.39% had a time interval of >1 year between the onset and last dose of pertussis vaccination， and 31.25% reported close contact with pertussis patients before the onset. The misdiagnosis rate of pertussis was as high as 92.19%. In contrast， the prevalence of anti-pertussis IgG antibody in health population was 1.05%. ConclusionFurther improvement in the laboratory testing capacity can help clarify the diagnosis of pertussis. Generally， children aged 0-1 year are mainly affected， of which vast majority have received at least one dose of pertussis vaccination. Clinical symptoms are characterized by whooping cough. Additionally， elevated white blood cells and lymphocytes should be on the alert to pertussis infection.