Interconnected clusters of invasive meningococcal disease due to Neisseria meningitidis serogroup C ST-11 (cc11), involving bisexuals and men who have sex with men, with discos and gay-venues hotspots of transmission, Tuscany, Italy, 2015 to 2016

Alessandro Miglietta,Chiara Azzari,Maria Moriondo,Paola Stefanelli,Cecilia Fazio,Francesco Paolo Maraglino,Fortunato D’Ancona,Stefania Iannazzo,Francesco Nieddu,Patrizio Pezzotti,Fabio Voller,Raniero Guerra,Gian Maria Rossolini,Arianna Neri,Giovanni Rezza,Francesco Innocenti

doi:10.2807/1560-7917.es.2018.23.34.1700636

Abstract

In 2015 an increased incidence of invasive meningococcal disease due to serogroup-C (MenC) occurred in Tuscany, Italy. This led the Regional Health Authority of Tuscany to implement a reactive immunisation campaign and to launch an epidemiological field investigation aiming to address targeted immunisation interventions. In 2011–14, 10 MenC cases had been reported compared with 62 cases in 2015–16. The case fatality rate was 21% (n = 13) and 51 cases (82.3%) were confirmed as C:P1.5–1,10–8:F3–6:ST-11(cc11). Overall, 17 clusters were recognised. Six discos and four gay-venues were found to have a role as transmission-hotspots, having been attended by 20 and 14 cases in the 10 days before symptoms onset. Ten and three cases occurred, respectively, among men who have sex with men (MSM) and bisexual individuals, who were involved in 11 clusters. In addition, heterosexual cases (n = 5) attending gay-venues were also found. Secondary cases were not identified. Molecular typing indicated close relationship with MenC clusters recently described among gay, bisexual and other MSM in Europe and the United States, suggesting a possible international spread of the serogroup-C-variant P1.5–1,10–8:F3–6:ST-11(cc11) in this population-group; however, epidemiological links were not identified. In December 2016, a targeted vaccination campaign involving discos and lesbian, gay, bisexual, and transgender (LGBT) associations was implemented. During 2017, 10 cases of MenC occurred, compared with 32 and 30 cases reported in 2015 and 2016 respectively, suggesting the effectiveness of the reactive and targeted immunisation programmes.

Highlights

Invasive meningococcal disease (IMD) is a severe, lifethreatening consequence of infection with the bacterium Neisseria meningitidis, a Gram-negative aerobic diplococcus able to colonise the nasopharynx [1]
Since the Rapid Communication dated 24 March 2016 [6], 19 additional laboratory-confirmed cases of meningococcal disease due to serogroup-C (MenC) were reported from the Regional Health Authority of Tuscany (RHAT) to the Italian National Surveillance System for Invasive Bacterial Disease at ISS, leading to a total of 62 cases in the period between 1 January 2015 and 31 December 2016
Outbreaks of MenC related to discos/gay-venues attendance are reported in literature [7,8,9,10,11,31,35,36]

Summary

Introduction

Invasive meningococcal disease (IMD) is a severe, lifethreatening consequence of infection with the bacterium Neisseria meningitidis, a Gram-negative aerobic diplococcus able to colonise the nasopharynx [1]. N. meningitidis can be classified into 13 serogroups, four of which (B,C,W,Y) are most commonly associated to IMD (i.e. septicaemia, meningitis or both) in Europe [2]. In Italy, the incidence of IMD is among the lowest in Europe, with a rate of 0.3 per 100,000 in 2015 [4]; but this rate is probably an underestimation [5]. H Strain 8: C:P1.5-1,10-8:F3-6:ST-11936 (cc11) (Neis0430/penA 398/248) (porB 2-2) (fHbp 1.13) (ET-15). VR1, VR2: fetA VR: ST (cc) (Neis0430/penA allele) (porB allele) (fHbp variant) (ET). a Strain 1: C:P1.5-1,10-8:F3-6:ST-11 (cc11)(Neis0430/penA 398/248) (porB 2-2) (fHbp 1.13) (ET-15). b Strain 2: C:P1.5-1,10-8:F3-6:ST-11/12051 (cc11) (Neis0430/penA 6/7) (porB 2-2) (fHbp 1.808) (ET-15). c Strain 3: C:P1.5-1,10-1:F3-6:ST-11 (cc11) (Neis0430/penA 398/248) (porB 2-2) (fHbp 1.13) (ET-15). d Strain 4: C:P1.5-1,10-8:F3-6:ST-2780 (cc11) (Neis0430/penA 398/248) (porB 2-2) (fHbp 1.13) (ET-15). e Strain 5 C:P1.5-1,10-8:F3-6:ST-11(cc11) (Neis0430/penA 6/7) (porB 2-2) (fHbp allele 669) (ET-15). f Strain 6: C:P1.7-4,14-3:F3-9:ST-1031 (cc334) (Neis0430/penA 162/599) (porB 2-227) (fHbp 2.19) (ET-15). g Strain 7: C:P1.5,2:F3-3:ST-11 (cc11) (Neis0430/penA 1/1) (porB 2-2) (fHbp 2.22) (ET-15). h Strain 8: C:P1.5-1,10-8:F3-6:ST-11936 (cc11) (Neis0430/penA 398/248) (porB 2-2) (fHbp 1.13) (ET-15). i Incomplete molecular typing due to low DNA concentration in the clinical sample

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Conclusion