Comparative Epidemiologic Characteristics of Pertussis in 10 Central and Eastern European Countries, 2000-2013

Abstract

We undertook an epidemiological survey of the annual incidence of pertussis reported from 2000 to 2013 in ten Central and Eastern European countries to ascertain whether increased pertussis reports in some countries share common underlying drivers or whether there are specific features in each country. The annual incidence of pertussis in the participating countries was obtained from relevant government institutions and/or national surveillance systems. We reviewed the changes in the pertussis incidence rates in each country to explore differences and/or similarities between countries in relation to pertussis surveillance; case definitions for detection and confirmation of pertussis; incidence and number of cases of pertussis by year, overall and by age group; population by year, overall and by age group; pertussis immunization schedule and coverage, and switch from whole-cell pertussis vaccines (wP) to acellular pertussis vaccines (aP). There was heterogeneity in the reported annual incidence rates and trends observed across countries. Reported pertussis incidence rates varied considerably, ranging from 0.01 to 96 per 100,000 population, with the highest rates generally reported in Estonia and the lowest in Hungary and Serbia. The greatest burden appears for the most part in infants (<1 year) in Bulgaria, Hungary, Latvia, Romania, and Serbia, but not in the other participating countries where the burden may have shifted to older children, though surveillance of adults may be inappropriate. There was no consistent pattern associated with the switch from wP to aP vaccines on reported pertussis incidence rates. The heterogeneity in reported data may be related to a number of factors including surveillance system characteristics or capabilities, different case definitions, type of pertussis confirmation tests used, public awareness of the disease, as well as real differences in the magnitude of the disease, or a combination of these factors. Our study highlights the need to standardize pertussis detection and confirmation in surveillance programs across Europe, complemented with carefully-designed seroprevalence studies using the same protocols and methodologies.

Conflict of interest statement

Competing Interests: The authors of this manuscript read the journal's policy and have the following competing interests: This study was funded by Sanofi Pasteur, Lyon, France. UH: received honoraria for educational activities from Sanofi Pasteur, Pfizer, and InfectoPharm. PA: employee of Sanofi Pasteur, as senior epidemiologist, between 2004 and 2013. RC: received research grants as clinical trial investigator from GlaxoSmithKline and Pfizer. AM: acted as a consultant for Sanofi Pasteur, GlaxoSmithKline, Pfizer, Danone, Nestle Abbott, Merck Sharp & Dohme and has received grants to attend scientific events. AN-O: acted as a consultant and a lecturer for Sanofi Pasteur and GlaxoSmithKline. RP: received research grants as principal investigator from GlaxoSmithKline, Sanofi Pasteur, Novartis, Baxter and Pfizer. DZ: received lecture fees from GlaxoSmithKline, Sanofi Pasteur, Merck Sharp & Dohme, and Abbott and has received sponsorship from GlaxoSmithKline, Sanofi Pasteur and Baxter to attend scientific meetings. ZK, KK, ZM, VP and VU: no conflict of interest relevant to this manuscript. There are no patents, products in development or marketed products to declare. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Pertussis incidence in the ten participating Central and Eastern European countries, 2000–2013.

aP: acellular pertussis vaccine combined with diphtheria and tetanus toxoids. wP; whole cell pertussis vaccine combined with diphtheria and tetanus toxoids. Data not available by age group for Lithuania.

Fig 2. Boxplot of overall annual pertussis incidence rates between 2000 and 2013 for each of the ten participating Central and Eastern European countries.

Each boxplot represents the median (black line in box) and the 25th and 75th percentile incidence rates (edges of the box). The whiskers represent 1.5 x inter-quartile range. Outliers are represented as blue dots.

Fig 3. Boxplot of the overall annual incidence of pertussis reported across all participating countries for each of the calendar years in the study period.

Each boxplot represents the median (black line in box) and the 25th and 75th percentile incidence rates (edges of the box). The whiskers represent 1.5 x inter-quartile range. Outliers are represented as blue dots.