The evolving epidemiology of invasive meningococcal disease: a two-year prospective, population-based study in children in the area of Athens

Risk Factors for Contracting Invasive Meningococcal Disease and Related Mortality: A Systematic Literature Review and Meta-analysis

OBJECTIVES

To describe risk factors (RFs) and quantify their effects in invasive meningococcal disease (IMD) and associated mortality across all age groups based on the available published literature.

METHODS

A systematic literature review (SLR) was conducted via MEDLINE® and Embase. Study selection, data extraction, and quality assessment were performed by two independent reviewers. Associations between RFs and outcomes were quantified via a meta-analysis (MA).

RESULTS

Seventy-four studies (date range 1950 - 2018) were included in the SLR. Statistically significant RFs for contracting IMD identified from the SLR (within-study) included previous IMD infection and young age (0 - 4 years). MA indicated that significant RFs for contracting IMD (11 studies) were: HIV-positive status, passive smoke exposure, and crowded living space. In the MA for IMD-related mortality risk (11 studies), age 25 - 45 years (vs. 0 - 5 years) and serogroup C (vs. serogroup B) were significantly associated with increased risk.

CONCLUSIONS

Previous findings of higher risk for IMD contraction with smoke exposure and crowded living conditions in children/adolescents have been extended by this SLR/MA to all age groups. We provide strong evidence for higher risk of IMD in HIV-positive individuals, and confirm previous findings of higher IMD-related mortality risk in adults aged 25 - 45.

Multicenter Hospital-Based Prospective Surveillance Study of Bacterial Agents Causing Meningitis and Seroprevalence of Different Serogroups of Neisseria meningitidis, Haemophilus influenzae Type b, and Streptococcus pneumoniae during 2015 to 2018 in Turkey

Acute bacterial meningitis (ABM) is one of the most common life-threatening infections in children. The incidence and prevalence of ABM vary both geographically and temporally; therefore, surveillance systems are necessary to determine the accurate burden of ABM. The Turkish Meningitis Surveillance Group has been performing a hospital-based meningitis surveillance study since 2005 across several regions in Turkey. Meningococcus was the major ABM-causing agent during the 2015-to-2018 period, during which MenB was the dominant serogroup.

The etiology of bacterial meningitis in Turkey changed after the implementation of conjugated vaccines against Streptococcus pneumoniae and Haemophilus influenzae type b (Hib) in the Turkish National Immunization Program (NIP). Administration of Hib vaccine and PCV-7 (7-valent pneumococcal conjugate vaccine) was implemented in NIP in 2006 and 2009, respectively. In 2011, PCV-7 was replaced with PCV-13. Meningococcal vaccines have not yet been included in Turkish NIP. This prospective study comprised 27 hospitals located in seven regions of Turkey and represented 45% of the population. Children aged between 1 month and 18 years who were hospitalized with suspected meningitis were included. Cerebrospinal fluid (CSF) samples were collected, and bacterial identification was made according to the multiplex PCR assay results. During the study period, 994 children were hospitalized for suspected meningitis, and Hib (n = 3, 2.4%), S. pneumoniae (n = 33, 26.4%), and Neisseria meningitidis (n = 89, 71%) were detected in 125 samples. The most common meningococcal serogroup was MenB. Serogroup W comprised 13.9% (n = 5) and 7.5% (n = 4) of the meningococci in 2015 to 2016 and 2017 to 2018, respectively. Serogroup C was not detected. There were four deaths in the study; one was a pneumococcus case, and the others were serogroup B meningococcus cases. The epidemiology of meningococcal diseases has varied over time in Turkey. Differing from the previous surveillance periods, MenB was the most common serogroup in the 2015-to-2018 period. Meningococcal epidemiology is so dynamic that, for vaccination policies, close monitoring is crucial.

IMPORTANCE Acute bacterial meningitis (ABM) is one of the most common life-threatening infections in children. The incidence and prevalence of ABM vary both geographically and temporally; therefore, surveillance systems are necessary to determine the accurate burden of ABM. The Turkish Meningitis Surveillance Group has been performing a hospital-based meningitis surveillance study since 2005 across several regions in Turkey. Meningococcus was the major ABM-causing agent during the 2015-to-2018 period, during which MenB was the dominant serogroup.

Characterization of invasive Neisseria meningitidis isolates recovered from children in Turkey during a period of increased serogroup B disease, 2013-2017

Diverse Neisseria meningitidis strains belonging to various serogroups and clonal complexes cause epidemic and endemic life-threatening disease worldwide. This study aimed to investigate the genetic diversity of recent invasive meningococci in Turkey with respect to multilocus sequence type (MLST) and also meningococcal serogroup B (MenB) vaccine antigens to enable assessment of potential MenB strain coverage using the genetic Meningococcal Antigen Typing System (gMATS). Fifty-four isolates, representing 37.5% of all pediatric (ages 0-18 years) invasive meningococcal disease cases in Turkey from January 2013 to December 2017, underwent genome sequence analysis. Thirty-six (66.7%) isolates were MenB, 10 (18.5%) were serogroup W (MenW), 4 (7.4%) were serogroup A (MenA), 3 (5.6%) were serogroup Y (MenY) and 1 (1.8%) was serogroup X (MenX). The MenB isolates were diverse with cc35 (19.4%), cc41/44 (19.4%) and cc32 (13.8%) as the most prevalent clonal complexes. The MenW isolates (n = 10) comprised cc11 (n = 5), ST-2754 (cc-unassigned; n = 4) and cc22 (n = 1). gMATS was indicative of high 4CMenB coverage (72.2-79.1%) of Turkish invasive MenB strains from pediatric patients. Strain coverage of several clonal complexes differed from that seen elsewhere in Europe highlighting the importance of performing local assessments and also the use of phenotypic methods, i.e. MATS, where possible. All of the isolates possessed in-frame fhbp alleles and so were potentially covered by MenB-fHbp. Continued surveillance is essential to guide recommendations for current and future vaccines as well as understanding changes in epidemiology.

Clinical usefulness and accuracy of polymerase chain reaction in the detection of bacterial meningitis agents in pediatric cerebrospinal fluid

Bacterial meningitis poses enormous healthcare challenges due to a high mortality, morbidity and sequelae. Neisseria (N.) meningitidis, Haemophilus (H.) influenzae, Streptococcus (S.) pneumoniae and S. agalactiae remain among the most prevalent infectious agents that cause bacterial meningitis in children. The objective of this study was the simultaneous detection of these pathogens in suspected cerebrospinal fluid (CSF) by using multiplex polymerase chain reaction (mPCR) and compare PCR results with standard diagnostics currently used in clinical practice. CSF specimens were obtained from 515 children (<5 years) clinically suspected of having acute bacterial meningitis. Based on bacterial culture, four isolates of salmonella sp and one Citrobacter freundii isolate were identified. The remaining 510 CSF specimens, having negative culture, were subjected to mPCR. Twenty-three (4.51%) CSF samples yielded a PCR positive signal. The pathogens identified were: S. pneumoniae (n=13), H. influenzae (n=7) and N. meningitidis (n=3). S. agalactiae was not detected. Using sequential multiplex PCR, serogrouping of S. pneumoniae revealed 3 different serotypes: serotype 19A (n=6), 19F (n=4) and serotype 23F (n=3). Only the serotype A was identified for the 3N. meningitidis isolates. Despite vaccination, S. pneumoniae remains a leading cause of pediatric invasive disease. Detecting causative organism remains the most critical aspect for management of children with suspected meningitis. PCR method is more sensitive and rapid than culture for detecting the infectious agents. Institution of PCR diagnostics is recommended for early and appropriate therapy.

Neisseria meningitidis Serogroup X ST-5799 (ST-22 complex) in Turkey: A unique pediatric case

Although outbreaks of Neisseria meningitidis serogroup X occured in a couple of African countries, a limited number of serogroup X meningococcal cases were reported in America and Europe as well as Turkey. Additionally, serogroup X is still not represented in current conjugated meningococcal vaccines. Here, we describe the first pediatric case with meningitis caused by Neisseria meningitidis serogroup X ST-5799 (ST-22 complex) that formed a distinct lineage.

Bacterial agents causing meningitis during 2013-2014 in Turkey: A multi-center hospital-based prospective surveillance study

This is an observational epidemiological study to describe causes of bacterial meningitis among persons between 1 month and 18 y of age who are hospitalized with suspected bacterial meningitis in 7 Turkish regions. covering 32% of the entire population of Turkey. We present here the results from 2013 and 2014. A clinical case with meningitis was defined according to followings: any sign of meningitis including fever, vomiting, headache, and meningeal irritation in children above one year of age and fever without any documented source, impaired consciousness, prostration and seizures in those < 1 y of age. Single tube multiplex PCR assay was performed for the simultaneous identification of bacterial agents. The specific gene targets were ctrA, bex, and ply for N. meningitidis, Hib, and S. pneumoniae, respectively. PCR positive samples were recorded as laboratory-confirmed acute bacterial meningitis. A total of 665 children were hospitalized for suspected acute meningitis. The annual incidences of acute laboratory-confirmed bacterial meningitis were 0.3 cases / 100,000 population in 2013 and 0.9 cases/100,000 in 2014. Of the 94 diagnosed cases of bacterial meningitis by PCR, 85 (90.4%) were meningococcal and 9 (9.6%) were pneumococcal. Hib was not detected in any of the patients. Among meningococcal meningitis, cases of serogroup Y, A, B and W-135 were 2.4% (n = 2), 3.5% (n = 3), 32.9% (n = 28), and 42.4% (n = 36). No serogroup C was detected among meningococcal cases. Successful vaccination policies for protection from bacterial meningitis are dependent on accurate determination of the etiology of bacterial meningitis. Additionally, the epidemiology of meningococcal disease is dynamic and close monitoring of serogroup distribution is comprehensively needed to assess the benefit of adding meningococcal vaccines to the routine immunization program.

Meningitis caused by Neisseria Meningitidis, Hemophilus Influenzae Type B and Streptococcus Pneumoniae during 2005-2012 in Turkey. A multicenter prospective surveillance study

Successful vaccination policies for protection from bacterial meningitis are dependent on determination of the etiology of bacterial meningitis. Cerebrospinal fluid (CSF) samples were obtained prospectively from children from 1 month to ≤18 years of age hospitalized with suspected meningitis, in order to determine the etiology of meningitis in Turkey. DNA evidence of Neisseria meningitidis (N. meningitidis), Streptococcus pneumoniae (S. pneumoniae), and Hemophilus influenzae type b (Hib) was detected using multiplex polymerase chain reaction (PCR). In total, 1452 CSF samples were evaluated and bacterial etiology was determined in 645 (44.4%) cases between 2005 and 2012; N. meningitidis was detected in 333 (51.6%), S. pneumoniae in 195 (30.2%), and Hib in 117 (18.1%) of the PCR positive samples. Of the 333 N. meningitidis positive samples 127 (38.1%) were identified as serogroup W-135, 87 (26.1%) serogroup B, 28 (8.4%) serogroup A and 3 (0.9%) serogroup Y; 88 (26.4%) were non-groupable. As vaccines against the most frequent bacterial isolates in this study are available and licensed, these results highlight the need for broad based protection against meningococcal disease in Turkey.

An epidemiological review of changes in meningococcal biology during the last 100 years

AIM

The aim of this study was to assess changes in trends of meningococcal disease and strain diversity of Neisseria meningitidis in Europe, South America, and Africa over the last 100 years.

METHODS

Healthcare databases and sources of grey literature were searched in 2012 and records were screened against the protocol eligibility criteria using a three-stage sifting process. Studies included in the review were subject to data extraction. Results were summarised using a narrative approach.

RESULTS

Serogroup A was the dominant cause of invasive meningococcal disease in Europe before and during World Wars I and II. Whilst serogroup B has been dominant from the 1970s in Europe and the 1980s in South America, outbreaks have emerged associated with serogroups W135 and Y in the twenty-first century. There has been a shift in the age groups affected by invasive meningococcal disease with an increase in incidence among the elderly associated with serogroup Y and a decline in serogroup C among adolescent populations. Recent outbreaks of serogroup W135 have occurred in some countries in South America. The epidemiological trend of invasive meningococcal disease has remained largely static across Africa and dominated by serogroup A although recently serogroups X and W135 have accounted for a large proportion of morbidity and mortality.

CONCLUSION

The epidemiology of N. meningitidis has been dynamic in Europe and South America especially over the last 30 years. Routine vaccination with serogroup C vaccines has led to reduced carriage and incidence of invasive meningococcal disease and herd immunity.

Comparison of cytokine gene polymorphisms among Greek patients with invasive meningococcal disease or viral meningitis

High levels of pro-inflammatory cytokines are implicated in the severity of invasive meningococcal disease (IMD) and viral meningitis (VM). This study compared single-nucleotide polymorphisms (SNPs) in pro- and anti-inflammatory cytokine genes among patients with VM or IMD. Patient DNA samples were prepared by the National Meningitis Reference Laboratory in Athens: n = 98 for IMD and n = 53 for VM. The results for both patient groups were compared with data published for healthy Greek control data. Real-time PCR was used to assess the interleukin (IL) gene SNPs IL6 G−174C, IL1B C−511T, IL1RN T+2018C, IL10 G−1082A and IL8 A−251T and the tumour necrosis factor α (TNF-α) SNP TNFA G−308A. Differences were compared by Fisher’s exact test. The genotype for high IL-6 responses was predominant among IMD (51 %, P = 0.0008) and VM (74.5 %, P<0.0001) patients compared with the controls (31 %). The genotype associated with high TNF-α responses was 5 % among controls and lower for IMD (1.1 %, P = 0.0014) and VM (0 %, P = 0.052). There was no difference for IL-8 SNPs between controls and IMD (P = 0.162), but the difference was significant for VM (P = 0.0025). IL-6 (P = 0.024) and IL-8 (P = 0.00004) SNPs differed between IMD and VM. Reports on associations between IL-8 SNPs and cytokine responses differ. Because of its role in neutrophil attraction, differences in frequencies of the IL-8 SNP for IMD and VM require further investigation.

A prospective study of etiology of childhood acute bacterial meningitis, Turkey

Vaccines to prevent bacterial meningitis in this region must provide reliable protection against serogroup W-135.

Determination of the etiology of bacterial meningitis and estimating cost of disease are important in guiding vaccination policies. To determine the incidence and etiology of meningitis in Turkey, cerebrospinal fluid (CSF) samples were obtained prospectively from children (1 month–17 years of age) with a clinical diagnosis of acute bacterial meningitis. Multiplex PCR was used to detect DNA evidence of Streptococcus pneumoniae, Haemophilus influenzae type b (Hib), and Neisseria meningitidis. In total, 408 CSF samples were collected, and bacterial etiology was determined in 243 cases; N. meningitidis was detected in 56.5%, S. pneumoniae in 22.5%, and Hib in 20.5% of the PCR-positive samples. Among N. meningitidis–positive CSF samples, 42.7%, 31.1%, 2.2%, and 0.7% belonged to serogroups W-135, B, Y, and A, respectively. This study highlights the emergence of serogroup W-135 disease in Turkey and concludes that vaccines to prevent meningococcal disease in this region must provide reliable protection against this serogroup.

Invasive meningococcal disease in children in Jerusalem

Neisseria meningitidis is an important cause of childhood meningitis and septicaemia. Between 1999 and 2005, 133 invasive meningococcal disease (IMD) cases occurred in Jerusalem, 112 (84.2%) of them in children aged 0-14 years. The annual incidence rate in Jerusalem was higher than the national average (2.45+/-0.6 vs. 1.13+/-0.16/100 000 population, P=0.002). Most of the children (82.1%) were from low socio-economic Arab and Jewish ultra-orthodox communities; mortality was higher among Arab than Jewish children (1.3 vs. 0.22/100 000 person-years, P=0.004). A cluster of 10 children with severe meningococcal sepsis (three fatalities) emerged in the winter of 2003-2004. Compared to the other 102 cases in 1999-2005 both meningococcaemia (100% vs. 51%, P=0.003) and mortality (30% vs. 6.9%, P=0.014) rates were higher. Serogroup B comprised 77.6% of the bacterial isolates. Pulsed-field gel electrophoresis showed considerable variability among cluster isolates, but significant resemblance in Arab cases throughout 1999-2005. The increased susceptibility of specific sub-populations to IMD necessitates further evaluation.

Invasive meningococcal disease in children in Greece: comparison of serogroup A disease with disease caused by other serogroups

Although invasive meningococcal disease caused by serogroup A is not prevalent in developed countries, a considerable number of cases were recently recorded in Greece. In this study, serogroup A meningococcal disease was compared prospectively with meningococcal disease caused by other serogroups, using similar settings of testing and management during a 5-year period between 1999 and 2003. The Neisseria meningitidis serogroup was determined in 262 cases. Serogroup B predominated, accounting for 158 (60%) of the cases. Serogroup A was second most frequent (19%), followed by serogroups W135 (11%), C (8%), and Y (2%). No cases due to serogroup C were recorded during the last year of the study. Patients with serogroup A disease were older and had a milder course compared to patients infected with serogroups B or C. Toxic appearance, purpura, thrombocytopenia, abnormal coagulation tests, and the need for admission to the intensive care unit, fluid resuscitation, inotropic drugs, and mechanical ventilation were less common. Although morbidity and mortality were lower in these patients, the differences were not significant. Serogroup B is predominant in our area, and the introduction of an effective vaccine against it is a priority. Serogroup A has emerged as the second most common serogroup, but the illness associated with it is milder.

Phenotypic assessment of Neisseria meningitidis isolates obtained from patients with invasive meningococcal disease in Greece, 1993–2003: Implications for serogroup B vaccines based on PorA serosubtype antigens

Serogroup B is the major isolate from patients with invasive meningococcal disease (IMD) in Greece. This study used the whole cell enzyme-linked immuosorbent assay (ELISA) with monoclonal antibodies to screen Neisseria meningitidis isolates obtained from patients with IMD between 1993 and 2003 to determine if serosubtypes included in the hexavalent Por A OMP vaccines being tested in northern Europe were prevalent in Greece. During this period there were significant changes in the proportions of serogroups B and C isolated from patients. Serogroup C was predominant in 1996-1997 but fell sharply with corresponding increases in serogroup B. Of the 591 isolates sent to the National Meningitis Reference Laboratory in Athens during this period, 325 (55%) were serogroup B. Among those tested for serosubtype, porA proteins used for the vaccine being tested in Britain were detected on 85/284 (30%) strains and for the vaccine being tested in the Netherlands 175/284 (62%). P1.14 (58/284, 20%) the predominant serosubtype among the Greek isolates, is not present in either vaccine formulation; 23/284 (8%) strains did not react with any of the monoclonal antibodies. Our results indicate that introduction of the vaccines currently being evaluated in northern Europe would not be warranted in the Greek population.

Meningococcal polysaccharide-protein conjugate vaccines

It is now 5 years since the UK became the first country to introduce the serogroup C meningococcal polysaccharide-protein conjugate vaccines (MenC) into its routine immunisation schedule. This article reviews the global use of MenC with particular reference to the range of immunisation strategies used internationally. To date, concerns that MenC may result in an increase in meningococcal disease due to non-C serogroups have not been realised. The vaccine has proved to be highly safe and effective; however, concerns have arisen regarding the duration of vaccine effectiveness. Although booster doses of MenC may potentially extend the duration of protection offered by the vaccine, there are, as yet, no studies assessing this option. Clinical trials are underway to assess new combination conjugate vaccines (containing A, C, Y, and W polysaccharides), and it is probable that these more broadly protective vaccines will become available in the near future.

Meningococcal vaccines

Meningococcal disease is one of the most feared and serious infections in the young and its prevention by vaccination is an important goal. The high degree of antigenic variability of the organism makes the meningococcus a challenging target for vaccine prevention. Meningococcal polysaccharide vaccines against serogroup A and C are efficacious and have been widely used, often in combination with serogroup Y and W135 components. Their relative lack of immunogenicity in young children and infants can be overcome by conjugation to a protein carrier. The effectiveness of serogroup C glycoconjugate vaccines in children of all ages has been demonstrated and they have now been introduced into routine vaccination schedules. Conjugate vaccines against other serogroups, including A, Y, and W135 will soon be available and it is hoped they may emulate this success. Prevention of serogroup B disease has proven more elusive. Several serogroup B vaccines based on outer membrane vesicles have been shown to be immunogenic and reasonably effective in adults and older children, but the protection offered by them is chiefly strain-specific. Multivalent recombinant PorA vaccines have been developed to broaden the protective effect, but no efficacy data are available as yet. Intensive efforts have been directed at other outer membrane protein vaccine candidates and lipopolysaccharide, and some of these have been shown to offer protection in experimental animal models. Nonpathogenic Neisseriae spp. such as Neisseria lactamica are also possible vaccine candidates. Previously unknown proteins have been identified from in silico analysis of the meningococcal genome and their vaccine potential explored. However, none of these has yet been presented as the 'universal' protective antigen and work in this field continues to be held back by our limited knowledge concerning the mechanisms of natural protection against serogroup B meningococci.

Invasive meningococcal disease presenting as Henoch-Sch�nlein purpura

Henoch-Schonlein purpura (HSP) is an acute systemic form of vasculitis that has been associated with a number of viral and bacterial infections. Described here are the cases of two children with invasive meningococcal disease who presented with clinical and laboratory findings typical of HSP. Meningococcal infection may have been the trigger for the manifestation of HSP in these patients.

Epidemiology of meningococcal disease in Switzerland, 1999-2002

In Switzerland, immunisation against serogroup C meningococcal disease is recommended for persons at increased risk but is not included in the national vaccination programme. The aim of this study was to present the nationwide surveillance data on invasive meningococcal disease collected from 1999 to 2002, emphasising the evolution in the absence of extended vaccination. The number of reported cases of meningococcal disease peaked at 178 cases in 2000 (incidence rate of 2.5/100,000 person-years), with 61% of all cases attributed to serogroup C meningococci (incidence rate, 1.5/100,000 person-years). Since 2001, a spontaneous decrease in the reported cases was observed, resulting in an overall incidence rate of 1.4/100,000 person-years in 2002 (serogroup C cases, 0.8/100,000 person-years). On the other hand, the case-fatality rate of serogroup C cases increased to 18% in 2002, leading to an increase in the overall case-fatality rate from 8% to 14% (P>0.05). The small sample size reduces the interpretability of this observation. However, when the introduction of a generalised vaccination against serogroup C meningococcal disease is discussed, the fluctuations in the number of vaccine-preventable deaths should receive greater attention.

Carriage ofNeisseria meningitidisandNeisseria lactamicain northern Greece

In response to an increase in the number of cases of invasive meningococcal disease (IMD) in northern regions of Greece, a survey was carried out to determine if there was an increase in carriage of Neisseria meningitidis, particularly in areas where there have been increases in immigrant populations from neighbouring countries. The second objective was to determine if there was an increase in the serogroup C:2a:P1.5,2 a phenotype associated with recent outbreaks or changes in antibiotic sensitivities. As carriage of Neisseria lactamica is associated with development of natural immunity to IMD, the third objective was to determine the carriage rate of N. lactamica in this population. Among 3167 individuals tested, meningococci were isolated from 334 (10.5%). Compared with our previous studies, the proportion of meningococcal carriers was significantly increased among children in secondary education (11.3%) (chi2=9.67, P<0.005) and military recruits (37.4%) (chi2=21.11, P<0.000). Only 5/334 (1.5%) isolates expressed the phenotype associated with the increase in IMD in Greece. N. lactamica was isolated from 146/3167 (4.6%) participants. It was isolated from 71/987 (7.2%) children attending primary or nursery schools; however, the highest proportion of carriers (11.3%) was found in the boarding school for young Albanian men. In the 21-59-year age range, the majority of N. lactamica isolates (22/25, 88%) were from women, probably due to closer or more prolonged contact with children in the primary school age range. Smoking was significantly associated with isolation of meningococci from men but not from women. Penicillin-insensitive strains (25/334, 7.5%) were identified in all four regions examined; the majority (14/25, 56%) were obtained from military personnel. We conclude that there was a higher proportion of carriers in the population of northern Greece; however, the increase in carriage rate was not associated with the influx of immigrants from neighbouring countries, and there was not a higher incidence of the C:2a:P1.5,2 strain responsible for increased disease activity in Greece in either the immigrant or local populations.