Pertussis incidence rates in Novi Sad (Serbia) before and during improved surveillance

Abstract

Introduction/Objective The Global Pertussis Initiative (GPI) proposed clinical case definitions for pertussis diagnosis in three different age cohorts in order to improve surveillance of pertussis especially in older children, adolescents, and adults. The main goal of this research was to compare the burden of pertussis in the city of Novi Sad before and after the introduction of improved surveillance using the GPI clinical case definitions of pertussis. Methods Baseline data on pertussis were obtained from routine (non-sentinel) reporting before improved surveillance was introduced. From September 16, 2012, clinical case definitions proposed by GPI were applied within improved (sentinel and hospital) surveillance, while surveillance clinical case definitions were not introduced within non-sentinel. To confirm the suspected diagnosis, sampling of nasopharyngeal swab and/or blood was obtained from all cases. The choice of laboratory method (PCR or ELISA) depended on the duration of coughing and the age of the patients. Data were statistically processed by SPSS Statistics, version 22. Results During the 12-year period before the introduction of improved surveillance, only two clinical pertussis cases were registered. In contrast, during the two-year period of improved surveillance, a total of 14 (season 2012/13) and 146 (season 2013/2014) confirmed pertussis cases were reported. Significant differences were determined in distribution of pertussis according to the type of surveillance and the level of health care. Conclusion Introduction of clinical case definitions proposed by GPI improved the quality of surveillance and enabled an insight in the distribution of pertussis in all age groups and at all levels of health care.

Evaluation of the diagnostic utility of the new clinical case definition of pertussis - experience from sentinel and hospital-based pertussis surveillance

“…Except for the pertussis outbreak in the families, there were no registered www.srpskiarhiv.rs Table 3. Diagnostic accuracy of signs and symptoms and their combinations of proposed case definitions of patients aged ≥ 10 years with suspected pertussis infection outbreaks in the population in the city of Novi Sad during our study period [8,9]. Because participants in our study were enrolled during an epidemic free year and because we included only those who fulfilled the required signs and symptoms for the three age groups, we are convinced that mentioned differences would have contributed to the discrepancy of the results in the cited study [10].…”

“…The recruitment period was from October 1, 2013 to September 30, 2014 (52 weeks). According to the GPI, methods have previously been described in detail [7,9]. Briefly, we simultaneously conducted prospective surveillance at both primary (outpatients) and tertiary (inpatients) health care levels in the city of Novi Sad.…”

“…Patient data collection, sampling, and transport of patient material, as well as the laboratory testing of samples and interpretation of results was performed according to the previously used methodology [7,9].…”

“…Until 2012, the epidemiology of pertussis in Novi Sad has not been described well, when an improved surveillance method for pertussis was introduced following the GPI recommendations [7]. We then determined that pertussis was widespread in our population, affecting patients of any age [8,9].…”

Seasonal distribution of pertussis

“…According to the 2011 census results, the South Bačka District has a population of 615,371 inhabitants, which covers 32% of the total Vojvodina population. As previously described in detail, the surveillance of pertussis was conducted in accordance with the recommendations given from the GPI [7,8]. In brief, there only patients that were included, who fulfilled one or more criteria of the GPI clinical case definitions of pertussis for three age groups (0-3 months old, 4 months-9 years old, and ≥10 years old).…”