A decade of invasive meningococcal disease surveillance in Poland.

Neisseria meningitidis is a leading etiologic agent of severe invasive disease. The objective of the study was to characterise invasive meningococcal disease (IMD) epidemiology in Poland during the last decade, based on laboratory confirmed cases.The study encompassed all invasive meningococci collected between 2002 and 2011 in the National Reference Centre for Bacterial Meningitis. The isolates were re-identified and characterised by susceptibility testing, MLST analysis, porA and fetA sequencing. A PCR technique was used for meningococcal identification directly from clinical materials.In the period studied, 1936 cases of IMD were confirmed, including 75.6% identified by culture. Seven IMD outbreaks, affecting mostly adolescents, were reported; all were caused by serogroup C meningococci of ST-11. The highest incidence was observed among children under one year of age (15.71/100,000 in 2011). The general case fatality rate in the years 2010-2011 was 10.0%. Meningococci of serogroup B, C, Y and W-135 were responsible for 48.8%, 36.6%, 1.2% and 1.2% of cases, respectively. All isolates were susceptible to third generation cephalosporins, chloramphenicol, ciprofloxacin, and 84.2% were susceptible to penicillin. MLST analysis (2009-2011) revealed that among serogroup B isolates the most represented were clonal complexes (CC) ST-32CC, ST-18CC, ST-41/44CC, ST-213CC and ST-269CC, and among serogroup C: ST-103CC, ST-41/44CC and ST-11CC.The detection of IMD in Poland has changed over time, but observed increase in the incidence of the disease was mostly attributed to changes in the surveillance system including an expanded case definition and inclusion of data from non-culture diagnostics

Serogroup distribution of meningococci responsible for invasive infections in Poland, 2002–2011.

<p>(n = 1936; UNK - cases with unknown serogroup).</p

The total annual incidence rates (/100,000) of invasive meningococcal disease (IMD)/meningitis rates in age groups in Poland based on laboratory-confirmed cases, including culture- and PCR-positive samples, 2002–2011 (only cases with known age were included when calculating the incidence) and total annual incidence rates of IMD registered by the compulsory notification system (NIPH-NIH).

a<p>%Cases <b>-</b> percentage of IMD cases in age group among all cases;</p>b<p>No cases - total number of cases in a particular year;</p>c<p>percentage of cases identified by PCR in a particular year;</p>d<p>Men-cult. - incidence rates of meningitis confirmed by culture only;</p>e<p>NIPH-NIH – total incidence of invasive meningococcal disease for all age groups registered by compulsory notification system run by the National Institute of Public Health – National Institute of Hygiene (Available: <a href="http://www.pzh.gov.pl/oldpage/epimeld/index_p.html" target="_blank">http://www.pzh.gov.pl/oldpage/epimeld/index_p.html</a>. Accessed 2013 May 24).</p

Incidence of invasive meningococcal disease (/100,000) case fatality rate (CFR) and percentage of cases with sequelae in age groups in Poland, 2010–2011 (only cases with known outcome were included when calculating the CFR, n = 458).

a<p>MenB CFR - case fatality rate associated with infections caused by serogroup B meningococci;</p>b<p>MenC CFR - case fatality rate associated with infections caused by serogroup C meningococci.</p

Map of Poland with the incidence rates (per 100,000) of invasive meningococcal disease in children under 1 year of age/all age groups, in 16 voivodeships, in years 2010–2011.

<p>The voivodeships with notified outbreaks during study period are marked in yellow (OUT. – outbreak, numbered like in the text, the year of the outbreak, in bracket there is number of outbreak cases).</p

Molecular characterization of meningococcal isolates of serogroup B and C belonging to the most dominant clonal complexes (CC) represented at least by 10 isolates, 2009–2011.

a<p>ST – sequence type.</p