Meningococcal serogroup Y disease in Europe: Continuation of high importance in some European regions in 2013

Abstract

Neisseria meningitidis or meningococcus is divided into 12 distinct serogroups of which A, B, C, W, X, and Y are medically most important and cause health problems in different parts of the world. The epidemiology of N. meningitidis is unpredictable over time and across geographic regions. Globally, serogroup A has been prevalent in the African "meningitis belt" whereas serogroup B and C have predominated in Europe. In a paper published earlier in this journal (1) , an increase in serogroup Y invasive meningococcal disease (IMD) in some European countries was reported based on the epidemiological data for 2010, 2011 and 2012. Here, we report additional data from 30 European countries indicating that high or increased serogroup Y disease levels have continued in 2013 in certain regions of Europe. In the Western and Central Europe, there were no major changes in the proportion of serogroup Y IMD cases in 2013 compared to 2012. In the Scandinavian countries, proportion of serogroup Y disease remained high, ranging from 26% to 51% in 2013. This was in contrast to Baltic, Eastern and most Southern European countries, where the proportion of serogroup Y IMD was low similarly to previous years. For the last 2 decades, the mean age of patients affected by serogroup Y was 41 y for 7 countries from which data was available and 50% of cases were in patients aged 45 to 88 y. The age distribution of serogroup Y was bimodal and did not change significantly despite the increase of the total number and the proportion of serogroup Y IMD in some European regions.

Keywords: Europe; IMD, Invasive meningococcal disease; Men, meningococcal.; Neisseria meningitidis; epidemiology; invasive meningococcal disease; meningococcal serogroup Y.

Figure 1.

Absolute numbers of N. meningitis serogroup Y cases in various European countries in 2013 and proportion of serogroup Y IMD in various European countries in 2010–2013. The figure is based on data communicated by the scientists listed in the Acknowledgment or published web pages of national institutes.² The data for 2013 is compared with data from 2010 to 2012, which has been communicated earlier.¹ Color coding refers to 2013 data. Data which were not available to the authors for countries are shown in white. For IMD cases in Luxemburg, no sero-grouping has been carried out in 2013. One case of IMD reported in Romania in 2013 was either caused by serogroup W or Y and the indicated proportion of 2.7% applies if this case was caused by serogroup Y.

Figure 2.

Mean age of patients affected by meningococcal serogroup Y from a variety of European countries between 2000 to 2013.

Figure 3.

Outlier Box Plot to see the age distribution of serogroup Y affected patients based on 7 European countries (see text). A line through the middle of the diamond would show the mean age, the median age by the vertical line right to the diamond. The inner quartile range representing the 25^th and 75^th quantiles is indicated by the horizontal box.