Influenza A and meningococcal disease

Epstein-Barr virus as promoter of Lemierre syndrome: systematic literature review

PURPOSE

To investigate a possible link between acute Epstein-Barr virus infection and Lemierre syndrome, a rare yet life-threatening infection.

METHODS

A systematic review was conducted adhering to the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Diagnosis criteria for Lemierre syndrome were established, and data extraction encompassed demographic data, clinical, and laboratory information.

RESULTS

Out of 985 initially identified papers, 132 articles were selected for the final analysis. They reported on 151 cases of Lemierre syndrome (76 female and 75 male patients with a median of 18 years) alongside interpretable results for Epstein-Barr virus serology. Among these, 38 cases (25%) tested positive for acute Epstein-Barr virus serology. There were no differences in terms of age, sex, or Fusobacterium presence between the serologically positive and negative groups. Conversely, instances of cervical thrombophlebitis and pulmonary complications were significantly higher (P = 0.0001) among those testing negative. The disease course was lethal in one case for each of the two groups.

CONCLUSIONS

This analysis provides evidence of an association between acute Epstein-Barr virus infection and Lemierre syndrome. Raising awareness of this link within the medical community is desirable.

A multicentre study reveals dysbiosis in the microbial co-infection and antimicrobial resistance gene profile in the nasopharynx of COVID-19 patients

The impact of SARS-CoV-2 infection on the nasopharyngeal microbiome has not been well characterised. We sequenced genetic material extracted from nasopharyngeal swabs of SARS-CoV-2-positive individuals who were asymptomatic (n = 14), had mild (n = 64) or severe symptoms (n = 11), as well as from SARS-CoV-2-negative individuals who had never-been infected (n = 5) or had recovered from infection (n = 7). Using robust filters, we identified 1345 taxa with approximately 0.1% or greater read abundance. Overall, the severe cohort microbiome was least diverse. Bacterial pathogens were found in all cohorts, but fungal species identifications were rare. Few taxa were common between cohorts suggesting a limited human nasopharynx core microbiome. Genes encoding resistance mechanisms to 10 antimicrobial classes (> 25% sequence coverages, 315 genes, 63 non-redundant) were identified, with β-lactam resistance genes near ubiquitous. Patients infected with SARS-CoV-2 (asymptomatic and mild) had a greater incidence of antibiotic resistance genes and a greater microbial burden than the SARS-CoV-2-negative individuals. This should be considered when deciding how to treat COVID-19 related bacterial infections.

A microfluidic fully paper-based analytical device integrated with loop-mediated isothermal amplification and nano-biosensors for rapid, sensitive, and specific quantitative detection of infectious diseases

Bacterial meningitis, an infection of the membranes (meninges) and cerebrospinal fluid (CSF) surrounding the brain and spinal cord, is one of the major causes of death and disability worldwide. Higher case-fatality rates and short survival times have been reported in developing countries. Hence, a quick, straightforward, and low-cost approach is in great demand for the diagnosis of meningitis. In this research, a microfluidic fully paper-based analytical device (μFPAD) integrated with loop-mediated isothermal amplification (LAMP) and ssDNA-functionalized graphene oxide (GO) nano-biosensors was developed for the first time for a simple, rapid, low-cost, and quantitative detection of the main meningitis-causing bacteria, Neisseria meningitidis (N. meningitidis). The results can be successfully read within 1 hour with the limit of detection (LOD) of 6 DNA copies per detection zone. This paper device also offers versatile functions by providing a qualitative diagnostic analysis (i.e., a yes or no answer), confirmatory testing, and quantitative analysis. These features make the presented μFPAD capable of a simple, highly sensitive, and specific diagnosis of N. meningitis. Furthermore, this microfluidic approach has great potential in the rapid detection of a wide variety of different other pathogens in low-resource settings.

Impact of COVID-19 Containment Strategies and Meningococcal Conjugate ACWY Vaccination on Meningococcal Carriage in Adolescents

OBJECTIVES

To examine if COVID-19 containment strategies were associated with reduced pharyngeal carriage of meningococci in adolescents. Also, to observe if carriage prevalence of meningococcal A, C, W and Y differed in meningococcal conjugate ACWY vaccinated and unvaccinated adolescents.

DESIGN

Repeat cross-sectional study of pharyngeal carriage.

SETTING

In 2020, recruitment commenced from February to March (pre-COVID-19) and recommenced from August to September (during COVID-19 measures) in South Australia.

PARTICIPANTS

Eligible participants were between 17 and 25 years of age and completed secondary school in South Australia in 2019.

RESULTS

A total of 1338 school leavers were enrolled in 2020, with a mean age of 18.6 years (standard deviation 0.6). Pharyngeal carriage of disease-associated meningococci was higher during the COVID-19 period compared with the pre-COVID-19 period (41/600 [6.83%] vs. 27/738 [3.66%]; adjusted odds ratio [aOR], 2.03; 95% CI: 1.22-3.39; P = 0.01). Nongroupable carriage decreased during COVID period (1.67% vs. 3.79%; aOR, 0.45; 95% CI: 0.22-0.95). Pharyngeal carriage of groups A, C, W and Y was similar among school leavers vaccinated with meningococcal conjugate ACWY (7/257 [2.72%]) compared with those unvaccinated (29/1081 [2.68%]; aOR, 0.86; 95% CI: 0.37-2.02; P = 0.73). Clonal complex 41/44 predominated in both periods.

CONCLUSIONS

Meningococcal carriage prevalence was not impacted by public health strategies to reduce severe acute respiratory syndrome coronavirus 2 transmission and is unlikely to be the mechanism for lower meningococcal disease incidence. As international travel resumes and influenza recirculates, clinicians must remain vigilant for signs and symptoms of meningococcal disease. Vaccinating people at the highest risk of invasive meningococcal disease remains crucial despite containment strategies.

Super Dominant Pathobiontic Bacteria in the Nasopharyngeal Microbiota Cause Secondary Bacterial Infection in COVID-19 Patients

Coronavirus disease 2019 (COVID-19) is a respiratory infectious disease responsible for many infections worldwide. Differences in respiratory microbiota may correlate with disease severity. Samples were collected from 20 severe and 51 mild COVID-19 patients. High-throughput sequencing of the 16S rRNA gene was used to analyze the bacterial community composition of the upper and lower respiratory tracts. The indices of diversity were analyzed. When one genus accounted for >50% of reads from a sample, it was defined as a super dominant pathobiontic bacterial genus (SDPG). In the upper respiratory tract, uniformity indices were significantly higher in the mild group than in the severe group (P < 0.001). In the lower respiratory tract, uniformity indices, richness indices, and the abundance-based coverage estimator were significantly higher in the mild group than in the severe group (P < 0.001). In patients with severe COVID-19, SDPGs were detected in 40.7% of upper and 63.2% of lower respiratory tract samples. In patients with mild COVID-19, only 10.8% of upper and 8.5% of lower respiratory tract samples yielded SDPGs. SDPGs were present in both upper and lower tracts in seven patients (35.0%), among which six (30.0%) patients possessed the same SDPG in the upper and lower tracts. However, no patients with mild infections had an SDPG in both tracts. Staphylococcus, Corynebacterium, and Acinetobacter were the main SDPGs. The number of SDPGs identified differed significantly between patients with mild and severe COVID-19 (P < 0.001). SDPGs in nasopharyngeal microbiota cause secondary bacterial infection in COVID-19 patients and aggravate pneumonia.

IMPORTANCE The nasopharyngeal microbiota is composed of a variety of not only the true commensal bacterial species but also the two-face pathobionts, which are one a harmless commensal bacterial species and the other a highly invasive and deadly pathogen. In a previous study, we found that the diversity of nasopharyngeal microbiota was lost in severe influenza patients. We named the genus that accounted for over 50% of microbiota abundance as super dominant pathobiontic genus, which could invade to cause severe pneumonia, leading to high fatality. Similar phenomena were found here for SARS-CoV-2 infection. The diversity of nasopharyngeal microbiota was lost in severe COVID-19 infection patients. SDPGs in nasopharyngeal microbiota were frequently detected in severe COVID-19 patients. Therefore, the SDPGs in nasopharynx microbiota might invade into low respiratory and be responsible for secondary bacterial pneumonia in patients with SARS-CoV-2 infection.

The Host-Pathogen Interactions and Epicellular Lifestyle of Neisseria meningitidis

Neisseria meningitidis is a gram-negative diplococcus and a transient commensal of the human nasopharynx. It shares and competes for this niche with a number of other Neisseria species including N. lactamica, N. cinerea and N. mucosa. Unlike these other members of the genus, N. meningitidis may become invasive, crossing the epithelium of the nasopharynx and entering the bloodstream, where it rapidly proliferates causing a syndrome known as Invasive Meningococcal Disease (IMD). IMD progresses rapidly to cause septic shock and meningitis and is often fatal despite aggressive antibiotic therapy. While many of the ways in which meningococci survive in the host environment have been well studied, recent insights into the interactions between N. meningitidis and the epithelial, serum, and endothelial environments have expanded our understanding of how IMD develops. This review seeks to incorporate recent work into the established model of pathogenesis. In particular, we focus on the competition that N. meningitidis faces in the nasopharynx from other Neisseria species, and how the genetic diversity of the meningococcus contributes to the wide range of inflammatory and pathogenic potentials observed among different lineages.

Excess invasive meningococcal disease associated with seasonal influenza, South Africa, 2003-2018

Background

Invasive meningococcal disease (IMD) is a devastating illness with high mortality rates. Like influenza, endemic IMD is seasonal, peaking in winter. Studies suggest that circulation of influenza virus may influence the timing and magnitude of IMD winter peaks.

Methods

This ecological study used weekly data from 2 nationwide surveillance programs: Viral Watch (proportion of outpatient influenza-positive cases from throat or nasal swab samples) and GERMS-SA (laboratory-confirmed cases of IMD), occurring across South Africa from 2003 through 2018 in all age bands. A bivariate time series analysis using wavelet transform was conducted to determine cocirculation of the diseases and the time lag between the peak seasons. We modeled excess meningococcal disease cases attributable to influenza cocirculation, using univariate regression spline models. Stata and R statistical software packages were used for the analysis.

Results

A total of 5256 laboratory-confirmed IMD cases were reported, with an average annual incidence of 0.23 episodes per 100 000 population and a mean seasonal peak during week 32 (±3 weeks). Forty-two percent of swab samples (10 421 of 24 741) were positive for influenza during the study period. The mean peak for all influenza occurred at week 26 (±4 weeks). There was an average lag time of 5 weeks between annual influenza and IMD seasons. Overall, 5% (1%–9%) of IMD cases can be attributable to influenza cocirculation, with, on average, 17 excess IMD cases per year attributable to influenza.

Conclusions

A quantifiable proportion of IMD in South Africa is associated with influenza cocirculation; therefore, seasonal influenza vaccination may have an effect on preventing a small portion of IMD in addition to preventing influenza.

Relationship between influenza and dengue outbreaks, and subsequent bacterial sepsis in French Guiana: A time series analysis

Background: Influenza has been shown to increase the risk for severe bacterial infection, in the tropics the seasonality of influenza epidemics is less marked, and this may not be the case. Dengue is often followed by prolonged asthenia and some physicians hypothesized increased susceptibility to infections based on anecdotal observations.

Design and Methods: Time series of influenza and dengue surveillance were confronted bacterial sepsis admissions to test the hypotheses. Monthly surveillance data on influenza and dengue and aggregated sepsis data in Cayenne hospital were matched between 24/10/2007 and 27/09/2016. An ARIMA (1,0,1) model was used.

Results The series of the number of monthly cases of sepsis was positively associated with the monthly number of cases of influenza at time t (β=0.001, p=0.0359). Forecasts were imperfectly correlated with sepsis since influenza is not the only risk factor for sepsis. None of the ARIMA models showed a significant link between the dengue series and the sepsis series.

Conclusions: There was thus no link between dengue epidemics and sepsis, but it was estimated that for every 1,000 cases of flu there was one additional case of sepsis. In this tropical setting, influenza was highly seasonal, and improved vaccination coverage could have benefits on sepsis.

Meningococcal Vaccination: Recommendations of the Advisory Committee on Immunization Practices, United States, 2020

This report compiles and summarizes all recommendations from CDC's Advisory Committee on Immunization Practices (ACIP) for use of meningococcal vaccines in the United States. As a comprehensive summary and update of previously published recommendations, it replaces all previously published reports and policy notes. This report also contains new recommendations for administration of booster doses of serogroup B meningococcal (MenB) vaccine for persons at increased risk for serogroup B meningococcal disease. These guidelines will be updated as needed on the basis of availability of new data or licensure of new meningococcal vaccines. ACIP recommends routine vaccination with a quadrivalent meningococcal conjugate vaccine (MenACWY) for adolescents aged 11 or 12 years, with a booster dose at age 16 years. ACIP also recommends routine vaccination with MenACWY for persons aged ≥2 months at increased risk for meningococcal disease caused by serogroups A, C, W, or Y, including persons who have persistent complement component deficiencies; persons receiving a complement inhibitor (e.g., eculizumab [Soliris] or ravulizumab [Ultomiris]); persons who have anatomic or functional asplenia; persons with human immunodeficiency virus infection; microbiologists routinely exposed to isolates of Neisseria meningitidis; persons identified to be at increased risk because of a meningococcal disease outbreak caused by serogroups A, C, W, or Y; persons who travel to or live in areas in which meningococcal disease is hyperendemic or epidemic; unvaccinated or incompletely vaccinated first-year college students living in residence halls; and military recruits. ACIP recommends MenACWY booster doses for previously vaccinated persons who become or remain at increased risk.In addition, ACIP recommends routine use of MenB vaccine series among persons aged ≥10 years who are at increased risk for serogroup B meningococcal disease, including persons who have persistent complement component deficiencies; persons receiving a complement inhibitor; persons who have anatomic or functional asplenia; microbiologists who are routinely exposed to isolates of N. meningitidis; and persons identified to be at increased risk because of a meningococcal disease outbreak caused by serogroup B. ACIP recommends MenB booster doses for previously vaccinated persons who become or remain at increased risk. In addition, ACIP recommends a MenB series for adolescents and young adults aged 16-23 years on the basis of shared clinical decision-making to provide short-term protection against disease caused by most strains of serogroup B N. meningitidis.

The Effect of Influenza Virus on the Human Oropharyngeal Microbiome

Background

Secondary bacterial infections are an important cause of morbidity and mortality associated with influenza infections. As bacterial disease can be caused by a disturbance of the host microbiome, we examined the impact of influenza on the upper respiratory tract microbiome in a human challenge study.

Methods

The dynamics and ecology of the throat microbiome were examined following an experimental influenza challenge of 52 previously-healthy adult volunteers with influenza A/Wisconsin/67/2005 (H3N2) by intranasal inoculation; 35 healthy control subjects were not subjected to the viral challenge. Serial oropharyngeal samples were taken over a 30-day period, and the V1-V3 region of the bacterial 16S ribosomal RNA sequences were amplified and sequenced to determine the composition of the microbiome. The carriage of pathogens was also detected.

Results

Of the 52 challenged individuals, 43 developed proven influenza infections, 33 of whom became symptomatic. None of the controls developed influenza, although 22% reported symptoms. The diversity of bacterial communities remained remarkably stable following the acquisition of influenza, with no significant differences over time between individuals with influenza and those in the control group. Influenza infection was not associated with perturbation of the microbiome at the level of phylum or genus. There was no change in colonization rates with Streptococcus pneumoniae or Neisseria meningitidis.

Conclusions

The throat microbiota is resilient to influenza infection, indicating the robustness of the upper-airway microbiome.

Super-dominant pathobiontic bacteria in the nasopharyngeal microbiota as causative agents of secondary bacterial infection in influenza patients

The source of secondary lower respiratory tract bacterial infections in influenza patients is not fully understood. A case–control study was conducted during the 2017–2018 influenza epidemic period in Beijing, China. Nasopharyngeal swabs were collected from 52 virologically confirmed influenza patients and 24 healthy medical staff. The nasopharyngeal microbiota taxonomic composition was analysed using high-throughput sequencing of the 16S rRNA gene V3–V4 regions. The super-dominant pathobiontic bacterial genus (SDPG) was defined as that accounting for >50% of sequences in a nasopharyngeal swab. We attempted to isolate bacteria of this genus from both nasopharyngeal swabs and lower-respiratory tract samples and analyse their genetic similarities. We observed a significantly lower taxonomy richness in influenza cases compared with healthy controls. A SDPG was detected in 61% of severe cases but in only 24% of mild cases and 29% of healthy controls. In 10 cases, the species isolated from lower-respiratory tract infection sites were identified as belonging to the nasopharyngeal microbiota SDPG. Genetically identical strains were isolated from both nasopharyngeal swabs and lower-respiratory tract infection sites, including 23 Acinetobacter baumannii strains from six severe cases, six Klebsiella pneumoniae strains from two severe cases, five Pseudomonas aeruginosa strains from one severe and one mild case, and four Corynebacterium striatum strains from two severe cases. The SDPG in the nasopharyngeal microbiota are the likely cause of subsequent infection in influenza patients.

Influenza increases invasive meningococcal disease risk in temperate countries

OBJECTIVES

Invasive meningococcal disease (IMD) is a severe bacterial infection that displays wintertime seasonality in temperate countries. Mechanisms driving seasonality are poorly understood and may include environmental conditions and/or respiratory virus infections. We evaluated the contribution of influenza and environmental conditions to IMD risk, using standardized methodology, across multiple geographical regions.

METHODS

We evaluated 3276 IMD cases occurring between January 1999 and December 2011 in 11 jurisdictions in Australia, Canada, France and the United States. Effects of environmental exposures and normalized weekly influenza activity on IMD risk were evaluated using a case-crossover design. Meta-analytic methods were used to evaluate homogeneity of effects and to identify sources of between-region heterogeneity.

RESULTS

After adjustment for environmental factors, elevated influenza activity at a 2-week lag was associated with increased IMD risk (adjusted odds ratio (OR) per standard deviation increase 1.29; 95% confidence interval, 1.04-1.59). This increase was homogeneous across the jurisdictions studied. By contrast, although associations between environmental exposures and IMD were identified in individual jurisdictions, none was generalizable.

CONCLUSIONS

Using a self-matched design that adjusts for both coseasonality and case characteristics, we found that surges in influenza activity result in an acute increase in population-level IMD risk. This effect is seen across diverse geographic regions in North America, France and Australia. The impact of influenza infection on downstream meningococcal risk should be considered a potential benefit of influenza immunization programmes.

Molecular diagnosis of microbial copathogens with influenza A(H1N1)pdm09 in Oaxaca, Mexico

Background

Multiple factors have been associated with the severity of infection by influenza A(H1N1)pdm09. These include H1N1 cases with proven coinfections showing clinical association with bacterial contagions.

Purpose

The objective was to identify H1N1 and copathogens in the Oaxaca (Mexico) population. A cross-sectional survey was conducted from 2009 to 2012. A total of 88 study patients with confirmed H1N1 by quantitative RT-PCR were recruited.

Methods

Total nucleic acid from clinical samples of study patients was analyzed using a TessArray RPM-Flu microarray assay to identify other respiratory pathogens.

Results

High prevalence of copathogens (77.3%; 68 patients harbored one to three pathogens), predominantly from Streptococcus, Haemophilus, Neisseria, and Pseudomonas, were detected. Three patients (3.4%) had four or five respiratory copathogens, whereas others (19.3%) had no copathogens. Copathogenic occurrence with Staphylococcus aureus was 5.7%, Coxsackie virus 2.3%, Moraxella catarrhalis 1.1%, Klebsiella pneumoniae 1.1%, and parainfluenza virus 3 1.1%. The number of patients with copathogens was four times higher to those with H1N1 alone (80.68% and 19.32%, respectively). Four individuals (4.5%; two males, one female, and one infant) who died due to H1N1 were observed to have harbored such copathogens as Streptococcus, Staphylococcus, Haemophilus, and Neisseria.

Conclusion

In summary, copathogens were found in a significant number (>50%) of cases of influenza in Oaxaca. Timely detection of coinfections producing increased acuity or severity of disease and treatment of affected patients is urgently needed.

Influenza interaction with cocirculating pathogens and its impact on surveillance, pathogenesis, and epidemic profile: A key role for mathematical modelling

Evidence is mounting that influenza virus interacts with other pathogens colonising or infecting the human respiratory tract. Taking into account interactions with other pathogens may be critical to determining the real influenza burden and the full impact of public health policies targeting influenza. This is particularly true for mathematical modelling studies, which have become critical in public health decision-making. Yet models usually focus on influenza virus acquisition and infection alone, thereby making broad oversimplifications of pathogen ecology. Herein, we report evidence of influenza virus interactions with bacteria and viruses and systematically review the modelling studies that have incorporated interactions. Despite the many studies examining possible associations between influenza and Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Neisseria meningitidis, respiratory syncytial virus (RSV), human rhinoviruses, human parainfluenza viruses, etc., very few mathematical models have integrated other pathogens alongside influenza. The notable exception is the pneumococcus-influenza interaction, for which several recent modelling studies demonstrate the power of dynamic modelling as an approach to test biological hypotheses on interaction mechanisms and estimate the strength of those interactions. We explore how different interference mechanisms may lead to unexpected incidence trends and possible misinterpretation, and we illustrate the impact of interactions on public health surveillance using simple transmission models. We demonstrate that the development of multipathogen models is essential to assessing the true public health burden of influenza and that it is needed to help improve planning and evaluation of control measures. Finally, we identify the public health, surveillance, modelling, and biological challenges and propose avenues of research for the coming years.

The association between respiratory tract infection incidence and localised meningitis epidemics: an analysis of high-resolution surveillance data from Burkina Faso

Meningococcal meningitis epidemics in the African meningitis belt consist of localised meningitis epidemics (LME) that reach attack proportions of 1% within a few weeks. A meningococcal serogroup A conjugate vaccine was introduced in meningitis belt countries from 2010 on, but LME due to other serogroups continue to occur. The mechanisms underlying LME are poorly understood, but an association with respiratory pathogens has been hypothesised. We analysed national routine surveillance data in high spatial resolution (health centre level) from 13 districts in Burkina Faso, 2004–2014. We defined LME as a weekly incidence rate of suspected meningitis ≥75 per 100,000 during ≥2 weeks; and high incidence episodes of respiratory tract infections (RTI) as the 5^th quintile of monthly incidences. We included 10,334 health centre month observations during the meningitis season (January-May), including 85 with LME, and 1891 (1820) high-incidence episodes of upper (lower) RTI. In mixed effects logistic regression accounting for spatial structure, and controlling for dust conditions, relative air humidity and month, the occurrence of LME was strongly associated with high incidence episodes of upper (odds ratio 23.9, 95%-confidence interval 3.1–185.3), but not lower RTI. In the African meningitis belt, meningitis epidemics may be triggered by outbreaks of upper RTI.

Control of invasive meningococcal disease: is it achievable?

Neisseria meningitidis still leads to deaths and severe disability in children, adolescents and adults. Six different capsular groups of N. meningitidis cause invasive meningococcal disease in the form of meningitis and septicaemia in humans. Although conjugate meningococcal vaccines have been developed to provide protection against four of the capsular groups causing most diseases in humans, vaccines against capsular group B, which causes 85% of cases in Australia and the United Kingdom, have only recently been developed. A capsular group B meningococcal vaccine - 4CMenB (Bexsero) - has recently been licensed in the European Union, Canada and Australia. In Australia, a submission for inclusion of 4CMenB in the funded national immunization programme has recently been rejected. The vaccine will now be introduced into the national immunization programme in the United Kingdom following negotiation of a cost-effective price. With the current low incidence of invasive meningococcal disease in many regions, cost-effectiveness of a new capsular group B meningococcal vaccine is borderline in both the United Kingdom and Australia. Cost-effectiveness of an infant programme is determined largely by the direct protection of those vaccinated and is driven by the higher rate of disease in this age group. However, for an adolescent programme to be cost-effective, it must provide both long-term protection against both disease and carriage. The potential of vaccination to reduce the rate of severe invasive disease is a real possibility. A dual approach using both an infant and adolescent immunization programme to provide direct protection to those age groups at highest risk of meningococcal disease and to optimize the potential herd immunity effects is likely to be the most effective means of reducing invasive meningococcal disease. This commentary aims to describe the known disease burden and consequences of meningococcal disease, and the development and potential effectiveness of new capsular group B meningococcal vaccines.

Influenza-Like Illness Diagnosis and Management in the Acute Care Setting

During influenza season, acute respiratory illness due to influenza is difficult to distinguish from other influenza-like illnesses, but testing should be reserved for situations when timely results will influence management or infection control measures. Immunization status and timing of disease onset notwithstanding, a neuraminidase inhibitor should be offered immediately for certain high-risk children; neuraminidase inhibitor treatment should be considered if shorter illness is warranted or an at-risk sibling may be protected. Antipyretics and cough control may be useful. Immunization with an age-appropriate dose of an inactivated influenza vaccine is the cornerstone of prevention for health care personnel and our patients.

The relationship between prior antimicrobial prescription and meningitis: a case-control study

BACKGROUND

Recent research into the role of the human microbiome in maintaining health has identified the potentially harmful impact of antimicrobials.

AIM

The association with bacterial and viral meningitis following antimicrobial prescription during the previous year was investigated to determine whether antimicrobials have a deleterious effect on the nasopharyngeal microbiome.

DESIGN AND SETTING

A case-control study (1:4 cases to controls) was conducted examining the rate of previous antimicrobial exposure in cases of meningitis and in a matched control group. Data from a UK primary care clinical database were analysed using conditional logistic regression.

RESULTS

A total of 7346 cases of meningitis were identified, 3307 (45%) viral, 1812 (25%) bacterial, and 2227 (30%) unspecified. The risks of viral (adjusted odds ratio [AOR] 2.45; 95% confidence interval [CI] = 2.24 to 2.68) or bacterial (AOR 1.98; 95% CI = 1.71 to 2.30) meningitis were both increased following antimicrobial prescription in the preceding year. Patients who received ≥4 antimicrobial prescriptions in the preceding year were at significantly increased risk of all types of meningitis (AOR 2.85; 95% CI = 2.44 to 3.34), bacterial meningitis (AOR 3.06; 95% CI = 2.26 to 4.15) and viral meningitis (AOR 3.23; 95% CI = 2.55 to 4.08) compared to their matched controls.

CONCLUSION

There was an increased risk of meningitis following antimicrobial prescription in the previous year. It is possible that this increase was due to an effect of antimicrobials on the microbiome or reflected an increased general susceptibility to infections in these patients.

Many respiratory viruses have temporal association with meningococcal disease

BACKGROUND

Previous ecological studies have shown a temporal and spatial association between influenza epidemics and meningococcal disease (MNG); however, none have examined more than two respiratory viruses.

METHODS

Data were obtained in Chile between 2000 and 2005 on confirmed cases of MNG and all confirmed cases of respiratory viruses (influenza A and B; parainfluenza; adenovirus; and respiratory syncytial virus [RSV]). Both variables were divided by epidemiological weeks, age range, and regions. Models of transference functions were run for rates of MNG.

RESULTS

In this period, 1022 reported cases of MNG and 34,737 cases of respiratory virus were identified (25,137 RSV; 4300 parainfluenza; 2527 influenza-A; 356 influenza-B; and 2417 adenovirus). RSV was the major independent virus temporally associated to MNG (it appears one week before MNG), followed by parainfluenza, influenza-B, adenovirus, and influenza-A.

CONCLUSIONS

The rate of MNG in Chile is temporally associated to all of the respiratory viruses studied, but with variability according age range, and regions.

Potential Impact of Co-Infections and Co-Morbidities Prevalent in Africa on Influenza Severity and Frequency: A Systematic Review

Infectious diseases and underlying medical conditions common to Africa may affect influenza frequency and severity. We conducted a systematic review of published studies on influenza and the following co-infections or co-morbidities that are prevalent in Africa: dengue, malaria, measles, meningococcus, Pneumocystis jirovecii pneumonia (PCP), hemoglobinopathies, and malnutrition. Articles were identified except for influenza and PCP. Very few studies were from Africa. Sickle cell disease, dengue, and measles co-infection were found to increase the severity of influenza disease, though this is based on few studies of dengue and measles and the measles study was of low quality. The frequency of influenza was increased among patients with sickle cell disease. Influenza infection increased the frequency of meningococcal disease. Studies on malaria and malnutrition found mixed results. Age-adjusted morbidity and mortality from influenza may be more common in Africa because infections and diseases common in the region lead to more severe outcomes and increase the influenza burden. However, gaps exist in our knowledge about these interactions.

RNA structures are involved in the thermoregulation of bacterial virulence-associated traits

Pathogenic bacteria are exposed to temperature changes during colonization of the human body and during exposure to environmental conditions. Virulence-associated traits are mainly expressed by pathogenic bacteria at 37°C. We review different cases of post-transcriptional regulation of virulence-associated proteins through RNA structures (called RNA thermometers or RNATs) that modulate the translation of mRNAs. The analysis of RNATs in pathogenic bacteria has started to produce a comprehensive picture of the structures involved, and of the genes regulated by this mechanism. However, we are still not able to predict the functionality of putative RNATs predicted by bioinformatics methods, and there is not a global approach to measure the effect of these RNA structures in gene regulation during bacterial infections.

Epidemiology of infant meningococcal disease in the United States, 2006-2012

BACKGROUND

The incidence of meningococcal disease is currently at historic lows in the United States; however, incidence remains highest among infants aged <1 year. With routine use of Haemophilus influenzae type b and pneumococcal vaccines in infants and children in the United States, Neisseria meningitidis remains an important cause of bacterial meningitis in young children.

METHODS

Data were collected from active, population- and laboratory-based surveillance for N meningitidis conducted through Active Bacterial Core surveillance during 2006 through 2012. Expanded data collection forms were completed for infant cases identified in the surveillance area during 2006 through 2010.

RESULTS

An estimated 113 cases of culture-confirmed meningococcal disease occurred annually among infants aged <1 year in the United States from 2006 through 2012, for an overall incidence of 2.74 per 100,000 infants. Among these cases, an estimated 6 deaths occurred. Serogroup B was responsible for 64%, serogroup C for 12%, and serogroup Y for 16% of infant cases. Based on the expanded data collection forms, a high proportion of infant cases (36/58, 62%) had a smoker in the household and the socioeconomic status of the census tracts where infant meningococcal cases resided was lower compared with the other Active Bacterial Core surveillance areas and the United States as a whole.

CONCLUSIONS

The burden of meningococcal disease remains highest in young infants and serogroup B predominates. Vaccines that provide long-term protection early in life have the potential to reduce the burden of meningococcal disease, especially if they provide protection against serogroup B meningococcal disease.

Neisserial Molecular Adaptations to the Nasopharyngeal Niche

The exclusive reservoir of the genus Neisseria is the human. Of the broad range of species that comprise the Neisseria, only two are frequently pathogenic, and only one of those is a resident of the nasopharynx. Although Neisseria meningitidis can cause severe disease if it invades the bloodstream, the vast majority of interactions between humans and Neisseria are benign, with the bacteria inhabiting its mucosal niche as a non-invasive commensal. Understandably, with the exception of Neisseria gonorrhoeae, which preferentially colonises the urogenital tract, the neisseriae are extremely well adapted to survival in the human nasopharynx, their sole biological niche. The purpose of this review is to provide an overview of the molecular mechanisms evolved by Neisseria to facilitate colonisation and survival within the nasopharynx, focussing on N. meningitidis. The organism has adapted to survive in aerosolised transmission and to attach to mucosal surfaces. It then has to replicate in a nutrition-poor environment and resist immune and competitive pressure within a polymicrobial complex. Temperature and relative gas concentrations (nitric oxide and oxygen) are likely to be potent initial signals of arrival within the nasopharyngeal environment, and this review will focus on how N. meningitidis responds to these to increase the likelihood of its survival.

The association of meningococcal disease with influenza in the United States, 1989-2009

Importance and Objective

Prior influenza infection is a risk factor for invasive meningococcal disease. Quantifying the fraction of meningococcal disease attributable to influenza could improve understanding of viral-bacterial interaction and indicate additional health benefits to influenza immunization.

Design, Setting and Participants

A time series analysis of the association of influenza and meningococcal disease using hospitalizations in 9 states from 1989–2009 included in the State Inpatient Databases from the Agency for Healthcare Research and Quality and the proportion of positive influenza tests by subtype reported to the Centers for Disease Control. The model accounts for the autocorrelation of meningococcal disease and influenza between weeks, temporal trends, co-circulating respiratory syncytial virus, and seasonality. The influenza-subtype-attributable fraction was estimated using the model coefficients. We analyzed the synchrony of seasonal peaks in hospitalizations for influenza, respiratory syncytial virus, and meningococcal disease.

Results and Conclusions

In 19 of 20 seasons, influenza peaked≤2 weeks before meningococcal disease, and peaks were highly correlated in time (ρ = 0.95; P <.001). H3N2 and H1N1 peaks were highly synchronized with meningococcal disease while pandemic H1N1, B, and respiratory syncytial virus were not. Over 20 years, 12.8% (95% CI, 9.1–15.0) of meningococcal disease can be attributable to influenza in the preceding weeks with H3N2 accounting for 5.2% (95% CI, 3.0–6.5), H1N1 4.3% (95% CI, 2.6–5.6), B 3.0% (95% CI, 0.8–4.9) and pH1N1 0.2% (95% CI, 0–0.4). During the height of influenza season, weekly attributable fractions reach 59%. While vaccination against meningococcal disease is the most important prevention strategy, influenza vaccination could provide further protection, particularly in young children where the meningococcal disease vaccine is not recommended or protective against the most common serogroup.

Household crowding, social mixing patterns and respiratory symptoms in seven countries of the African meningitis belt

Objectives

To describe the variation in household crowding and social mixing patterns in the African meningitis belt and to assess any association with self-reported recent respiratory symptoms.

Methods

In 2010, the African Meningococcal Carriage Consortium (MenAfriCar) conducted cross-sectional surveys in urban and rural areas of seven countries. The number of household members, rooms per household, attendance at social gatherings and meeting places were recorded. Associations with self-reported recent respiratory symptoms were analysed by univariate and multivariate regression models.

Results

The geometric mean people per room ranged from 1.9 to 2.8 between Ghana and Ethiopia respectively. Attendance at different types of social gatherings was variable by country, ranging from 0.5 to 1.5 per week. Those who attended 3 or more different types of social gatherings a week (frequent mixers) were more likely to be older, male (OR 1.27, p<0.001) and live in urban areas (OR 1.45, p<0.001). Frequent mixing and young age, but not increased household crowding, were associated with higher odds of self-reported respiratory symptoms (aOR 2.2, p<0.001 and OR 2.8, p<0.001 respectively). A limitation is that we did not measure school and workplace attendance.

Conclusion

There are substantial variations in household crowding and social mixing patterns across the African meningitis belt. This study finds a clear association between age, increased social mixing and respiratory symptoms. It lays the foundation for designing and implementing more detailed studies of social contact patterns in this region.

Bacterial and viral infections associated with influenza

Influenza‐associated bacterial and viral infections are responsible for high levels of morbidity and death during pandemic and seasonal influenza episodes. A review was undertaken to assess and evaluate the incidence, epidemiology, aetiology, clinical importance and impact of bacterial and viral co‐infection and secondary infection associated with influenza. A review was carried out of published articles covering bacterial and viral infections associated with pandemic and seasonal influenza between 1918 and 2009 (and published through December 2011) to include both pulmonary and extra‐pulmonary infections. While pneumococcal infection remains the predominant cause of bacterial pneumonia, the review highlights the importance of other co‐ and secondary bacterial and viral infections associated with influenza, and the emergence of newly identified dual infections associated with the 2009 H1N1 pandemic strain. Severe influenza‐associated pneumonia is often bacterial and will necessitate antibiotic treatment. In addition to the well‐known bacterial causes, less common bacteria such as Legionella pneumophila may also be associated with influenza when new influenza strains emerge. This review should provide clinicians with an overview of the range of bacterial and viral co‐ or secondary infections that could present with influenza illness.

Temperature triggers immune evasion by Neisseria meningitidis

Neisseria meningitidis has several strategies to evade complement-mediated killing, and these contribute to its ability to cause septicaemic disease and meningitis. However, the meningococcus is primarily an obligate commensal of the human nasopharynx, and it is unclear why the bacterium has evolved exquisite mechanisms to avoid host immunity. Here we demonstrate that mechanisms of meningococcal immune evasion and resistance against complement increase in response to an increase in ambient temperature. We have identified three independent RNA thermosensors located in the 5' untranslated regions of genes necessary for capsule biosynthesis, the expression of factor H binding protein, and sialylation of lipopolysaccharide, which are essential for meningococcal resistance against immune killing. Therefore increased temperature (which occurs during inflammation) acts as a 'danger signal' for the meningococcus, enhancing its defence against human immune killing. Infection with viral pathogens, such as influenza, leads to inflammation in the nasopharynx with an increased temperature and recruitment of immune effectors. Thermoregulation of immune defence could offer an adaptive advantage to the meningococcus during co-infection with other pathogens, and promote the emergence of virulence in an otherwise commensal bacterium.

Virus-associated apoptosis of blood neutrophils as a risk factor for invasive meningococcal disease

Aims

To quantify a range of haematological indicators of viral infection (leucocyte apoptosis, cytopenia of normal lymphocytes, reactive lymphocyte increase, neutropenia) in patients with recent onset invasive meningococcal disease (IMD), with a view to test the association of viral infection with IMD and identify possible haematological risk factors for its development.

Subjects and methods

88 patients with recent onset IMD, classified on clinical severity as fatal (n=14), septic shock survived (n=26) and no shock (n=48), and 50 healthy controls were studied. Blood film microscopy and leucocyte counts were used to quantify the virus-associated indicators. Cocci-containing neutrophils were also quantified.

Results

All viral parameters were significantly more frequent or higher in patients than controls, with leucocyte apoptosis found only in the patients. A significant gradient in accord with clinical severity was found for neutrophil and lymphocyte apoptosis, neutropenia and cocci-containing neutrophils. Crucially, apoptotic neutrophils did not contain cocci, and cocci-containing neutrophils were not apoptotic.

Conclusions

The correlation between magnitude of neutrophil apoptosis and severity of IMD suggests a cause–effect relationship. We propose that neutrophil apoptosis is more likely a facilitator rather than an effect of IMD for these reasons: (1) apoptotic neutrophils did not contain cocci and cocci-containing neutrophils were not apoptotic, (2) leucocyte apoptosis is a recognised viral effect and (3) Neisseria meningitidis is incapable of producing a Panton–Valentine type leucocidin. The lymphocyte apoptosis which accompanies neutrophil death may contribute to risk by impairing the generation of microbicidal antibody. Leucocyte apoptosis is a morphological expression of viral immunosuppression and, we suggest, is a likely contributor to a range of viral effects.

Meningococcal disease: changes in epidemiology and prevention

The human bacterial pathogen Neisseria meningitidis remains a serious worldwide health threat, but progress is being made toward the control of meningococcal infections. This review summarizes current knowledge of the global epidemiology and the pathophysiology of meningococcal disease, as well as recent advances in prevention by new vaccines. Meningococcal disease patterns and incidence can vary dramatically, both geographically and over time in populations, influenced by differences in invasive meningococcal capsular serogroups and specific genotypes designated as ST clonal complexes. Serogroup A (ST-5, ST-7), B (ST-41/44, ST-32, ST-18, ST-269, ST-8, ST-35), C (ST-11), Y (ST-23, ST-167), W-135 (ST-11) and X (ST-181) meningococci currently cause almost all invasive disease. Serogroups B, C, and Y are responsible for the majority of cases in Europe, the Americas, and Oceania; serogroup A has been associated with the highest incidence (up to 1000 per 100,000 cases) and large outbreaks of meningococcal disease in sub-Saharan Africa and previously Asia; and serogroups W-135 and X have emerged to cause major disease outbreaks in sub-Saharan Africa. Significant declines in meningococcal disease have occurred in the last decade in many developed countries. In part, the decline is related to the introduction of new meningococcal vaccines. Serogroup C polysaccharide-protein conjugate vaccines were introduced over a decade ago, first in the UK in a mass vaccination campaign, and are now widely used; multivalent meningococcal conjugate vaccines containing serogroups A, C, W-135, and/or Y were first used for adolescents in the US in 2005 and have now expanded indications for infants and young children, and a new serogroup A conjugate vaccine has recently been introduced in sub-Saharan Africa. The effectiveness of these conjugate vaccines has been enhanced by the prevention of person-to-person transmission and herd immunity. In addition, progress has been made in serogroup B-specific vaccines based on conserved proteins and outer membrane vesicles. However, continued global surveillance is essential in understanding and predicting the dynamic changes in the epidemiology and biological basis of meningococcal disease and to influence the recommendations for current and future vaccines or other prevention strategies.

Modelling seasonal variations in the age and incidence of Kawasaki disease to explore possible infectious aetiologies

The average age of infection is expected to vary during seasonal epidemics in a way that is predictable from the epidemiological features, such as the duration of infectiousness and the nature of population mixing. However, it is not known whether such changes can be detected and verified using routinely collected data. We examined the correlation between the weekly number and average age of cases using data on pre-vaccination measles and rotavirus. We show that age-incidence patterns can be observed and predicted for these childhood infections. Incorporating additional information about important features of the transmission dynamics improves the correspondence between model predictions and empirical data. We then explored whether knowledge of the age-incidence pattern can shed light on the epidemiological features of diseases of unknown aetiology, such as Kawasaki disease (KD). Our results indicate KD is unlikely to be triggered by a single acute immunizing infection, but is consistent with an infection of longer duration, a non-immunizing infection or co-infection with an acute agent and one with longer duration. Age-incidence patterns can lend insight into important epidemiological features of infections, providing information on transmission-relevant population mixing for known infections and clues about the aetiology of complex paediatric diseases.

Estimating Individual-Level Risk in Spatial Epidemiology Using Spatially Aggregated Information on the Population at Risk

We propose a novel alternative to case-control sampling for the estimation of individual-level risk in spatial epidemiology. Our approach uses weighted estimating equations to estimate regression parameters in the intensity function of an inhomogeneous spatial point process, when information on risk-factors is available at the individual level for cases, but only at a spatially aggregated level for the population at risk. We develop data-driven methods to select the weights used in the estimating equations and show through simulation that the choice of weights can have a major impact on efficiency of estimation. We develop a formal test to detect non-Poisson behavior in the underlying point process and assess the performance of the test using simulations of Poisson and Poisson cluster point processes. We apply our methods to data on the spatial distribution of childhood meningococcal disease cases in Merseyside, U.K. between 1981 and 2007.

Genetic variant associations of human SP-A and SP-D with acute and chronic lung injury

Pulmonary surfactant, a lipoprotein complex, maintains alveolar integrity and plays an important role in lung host defense, and control of inflammation. Altered inflammatory processes and surfactant dysfunction are well described events that occur in patients with acute or chronic lung disease that can develop secondary to a variety of insults. Genetic variants of surfactant proteins, including single nucleotide polymorphisms, haplotypes, and other genetic variations have been associated with acute and chronic lung disease throughout life in several populations and study groups. The hydrophilic surfactant proteins SP-A and SP-D, also known as collectins, in addition to their surfactant-related functions, are important innate immunity molecules as these, among others, exhibit the ability to bind and enhance clearance of a wide range of pathogens and allergens. This review focuses on published association studies of human surfactant proteins A and D genetic polymorphisms with respiratory, and non-respiratory diseases in adults, children, and newborns. The potential role of genetic variations in pulmonary disease or pathogenesis is discussed following an evaluation, and comparison of the available literature.

Mechanisms of meningococcal colonisation

Despite advances against infectious diseases over the past century, Neisseria meningitidis remains a major causative agent of meningitis and septicaemia worldwide. Its adaptation for survival in the human nasopharynx makes the meningococcus a highly successful commensal bacterium. Recent progress has been made in understanding the mechanisms that enable neisserial colonisation, in terms of the role of type IV pili, the impact of other adhesins, biofilm formation, nutrient acquisition and resistance to host immune defences. Refinements in cell-based and in vivo models will lead to improved understanding of the colonisation process, and hopefully to more effective vaccines and therapeutic strategies.

Favorable outcome after life-threatening meningococcal disease complicating influenza A(H1N1) infection

PURPOSE

Neurological complications of influenza A(H1N1) have been reported in several patients since the onset of the pandemic in 2009. However, meningococcal disease complicating influenza A(H1N1) has not been reported.

PATIENTS

Two patients were admitted to an intensive care unit (ICU) for altered mental status, fever, and rapidly spreading petechial purpura. They were diagnosed with meningococcal meningitis and/or meningococcemia and influenza A(H1N1) co-infection.

CONCLUSIONS

Meningococcal disease presenting as meningitis and/or meningococcemia is among the potential complications of influenza A(H1N1) infection. Physicians should be aware of this co-infection, as it must be detected and treated promptly with antibiotics in addition to supportive care.

Respiratory virus infection and risk of invasive meningococcal disease in central Ontario, Canada

Background

In temperate climates, invasive meningococcal disease (IMD) incidence tends to coincide with or closely follow peak incidence of influenza virus infection; at a seasonal level, increased influenza activity frequently correlates with increased seasonal risk of IMD.

Methods

We evaluated 240 cases of IMD reported in central Ontario, Canada, from 2000 to 2006. Associations between environmental and virological (influenza A, influenza B and respiratory syncytial virus (RSV)) exposures and IMD incidence were evaluated using negative binomial regression models controlling for seasonal oscillation. Acute effects of weekly respiratory virus activity on IMD risk were evaluated using a matched-period case-crossover design with random directionality of control selection. Effects were estimated using conditional logistic regression.

Results

Multivariable negative binomial regression identified elevated IMD risk with increasing influenza A activity (per 100 case increase, incidence rate ratio = 1.18, 95% confidence interval (CI): 1.06, 1.31). In case-crossover models, increasing weekly influenza A activity was associated with an acute increase in the risk of IMD (per 100 case increase, odds ratio (OR)  = 2.03, 95% CI: 1.28 to 3.23). Increasing weekly RSV activity was associated with increased risk of IMD after adjusting for RSV activity in the previous 3 weeks (per 100 case increase, OR = 4.31, 95% CI: 1.14, 16.32). No change in disease risk was seen with increasing influenza B activity.

Conclusions

We have identified an acute effect of influenza A and RSV activity on IMD risk. If confirmed, these finding suggest that influenza vaccination may have the indirect benefit of reducing IMD risk.

Epidemiological profile of meningococcal disease in the United States

Neisseria meningitidis is a leading cause of bacterial meningitis and other serious infections worldwide. The epidemiological profile of N. meningitidis is highly changeable, with great differences in disease incidence and serogroup distribution. Six serogroups (namely serogroups A, B, C, W-135, X, and Y) are responsible for most cases of meningococcal disease worldwide; the epidemiological profile of disease caused by each serogroup is unique. No vaccine is available for endemic disease caused by serogroup B strains. Two tetravalent (A/C/Y/W-135) meningococcal vaccines are licensed in the United States: a purified polysaccharide product and a polysaccharide-protein conjugate vaccine. The conjugate vaccine is recommended for all adolescents, although vaccine coverage remains low, and other groups at high risk of infection. A comprehensive program to prevent invasive meningococcal disease in the United States will require vaccination of infants; several conjugate vaccines for infants may become available in the near future. Broadly protective vaccines for endemic serogroup B disease are also needed.

Intervention strategies for an influenza pandemic taking into account secondary bacterial infections

Influenza infections often predispose individuals to consecutive bacterial infections. Both during seasonal and pandemic influenza outbreaks, morbidity and mortality due to secondary bacterial infections can be substantial. With the help of a mathematical model, we investigate the potential impact of such bacterial infections during an influenza pandemic, and we analyze how antiviral and antibacterial treatment or prophylaxis affect morbidity and mortality. We consider different scenarios for the spread of bacteria, the emergence of antiviral resistance, and different levels of severity for influenza infections (1918-like and 2009-like). We find that while antibacterial intervention strategies are unlikely to play an important role in reducing the overall number of cases, such interventions can lead to a significant reduction in mortality and in the number of bacterial infections. Antibacterial interventions become even more important if one considers the--very likely--scenario that during a pandemic outbreak, influenza strains resistant to antivirals emerge. Overall, our study suggests that pandemic preparedness plans should consider intervention strategies based on antibacterial treatment or prophylaxis through drugs or vaccines as part of the overall control strategy. A major caveat for our results is the lack of data that would allow precise estimation of many of the model parameters. As our results show, this leads to very large uncertainty in model outcomes. As we discuss, precise assessment of the impact of antibacterial strategies during an influenza pandemic will require the collection of further data to better estimate key parameters, especially those related to the bacterial infections and the impact of antibacterial intervention strategies.

Multivariate modelling of infectious disease surveillance data

This paper describes a model-based approach to analyse multivariate time series data on counts of infectious diseases. It extends a method previously described in the literature to deal with possible dependence between disease counts from different pathogens. In a spatio-temporal context it is proposed to include additional information on global dispersal of the pathogen in the model. Two examples are given: the first describes an analysis of weekly influenza and meningococcal disease counts from Germany. The second gives an analysis of the spatio-temporal spread of influenza in the U.S.A., 1996-2006, using air traffic information. Maximum likelihood estimates in this non-standard model class are obtained using general optimization routines, which are integrated in the R package surveillance.

Invasive meningococcal disease in Malta: an epidemiological overview, 1994-2007

Since 1996, Malta has experienced an upsurge of invasive meningococcal disease (IMD) following an almost 30 year period with a negligible number of annually reported cases. We reviewed the 233 IMD cases notified during a 14 year period (1994-2007), and analysed epidemiological and laboratory surveillance data. The crude incidence per 100,000 inhabitants peaked in 2000 at 8.1 [95 % confidence interval (CI) 5.7-11.6] and again in 2006 at 8.9 (95 % CI 6.4-12.4), thereby placing Malta amongst the countries with the highest incidence of the disease in Europe. Of the total cases, 137 (59 %) were confirmed and 30 (13 %) were classified as probable. However, 66 cases (28 %) had no laboratory evidence of the disease and were classified as possible. Information on the serogroup was available for 114 cases. Serogroup B formed the largest proportion (76 %, n=87) followed by serogroup C (16 %, n=18). B : 4 : P1.19,15 strains (n=46) predominated throughout the study period since their first identification in 1998. With 28 deaths attributed to IMD, the overall case fatality rate was 12 %. Apart from stressing the importance of maintaining high vigilance for IMD, our findings underscore the importance of enhancing laboratory surveillance of the disease, including characterization of the meningococci. Until vaccines against a broad range of serogroup B meningococci become available for universal use, the main methods of control remain the early treatment of cases and the prevention of secondary cases.

Influenza A virus neuraminidase enhances meningococcal adhesion to epithelial cells through interaction with sialic acid-containing meningococcal capsules

The underlying mechanisms of the epidemiological association between influenza virus infections and Neisseria meningitidis invasive infections are not fully understood. Here we report that adhesion of N. meningitidis to human Hec-1-B epithelial cells is enhanced by influenza A virus (IAV) infection. A potential role of the viral neuraminidase (NA) in facilitating meningococcal adhesion to influenza virus-infected epithelial cells was examined. Expression of a recombinant IAV NA in Hec-1-B human epithelial cells increased the adhesion of strains of N. meningitidis belonging to the sialic acid-containing capsular serogroups B, C, and W135 but not to the mannosamine phosphate-containing capsular serogroup A. Adhesion enhancement was not observed with an inactive NA mutant or in the presence of an NA inhibitor (zanamivir). Furthermore, purified IAV NA was shown to cleave sialic acid-containing capsular polysaccharides of N. meningitidis. On the whole, our findings suggest that a direct interaction between the NA of IAV and the capsule of N. meningitidis enhances bacterial adhesion to cultured epithelial cells, most likely through cleavage of capsular sialic acid-containing polysaccharides. A better understanding of the association between IAV and invasive meningococcal infections should help to set up improved control strategies against these seasonal dual viral-bacterial infections.

Global epidemiology of meningococcal disease

As reviewed in this paper, meningococcal disease epidemiology varies substantially by geographic area and time. The disease can occur as sporadic cases, outbreaks, and large epidemics. Surveillance is crucial for understanding meningococcal disease epidemiology, as well as the need for and impact of vaccination. Despite limited data from some regions of the world and constant change, current meningococcal disease epidemiology can be summarized by region. By far the highest incidence of meningococcal disease occurs in the meningitis belt of sub-Saharan Africa. During epidemics, the incidence can approach 1000 per 100,000, or 1% of the population. Serogroup A has been the most important serogroup in this region. However, serogroup C disease has also occurred, as has serogroup X disease and, most recently, serogroup W-135 disease. In the Americas, the reported incidence of disease, in the range of 0.3-4 cases per 100,000 population, is much lower than in the meningitis belt. In addition, in some countries such as the United States, the incidence is at an historical low. The bulk of the disease in the Americas is caused by serogroups C and B, although serogroup Y causes a substantial proportion of infections in some countries and W-135 is becoming increasingly problematic as well. The majority of meningococcal disease in European countries, which ranges in incidence from 0.2 to 14 cases per 100,000, is caused by serogroup B strains, particularly in countries that have introduced serogroup C meningococcal conjugate vaccines. Serogroup B also predominates in Australia and New Zealand, in Australia because of the control of serogroup C disease through vaccination and in New Zealand because of a serogroup B epidemic. Based on limited data, most disease in Asia is caused by serogroup A and C strains. Although this review summarizes the current status of meningococcal disease epidemiology, the dynamic nature of this disease requires ongoing surveillance both to provide data for vaccine formulation and vaccine policy and to monitor the impact of vaccines following introduction.

Meningococcal C conjugate vaccine: the experience in England and Wales

Meningococcal C conjugate vaccine was introduced in the UK in November 1999 together with a comprehensive meningococcal surveillance strategy to support and inform the vaccine programme. These surveillance data have provided important information on the long-term effectiveness of the programme, through direct and indirect protection, and on the prevalent serotypes and serosubtypes causing invasive meningococcal infection subsequent to vaccine introduction. The MCC immunization programme has been extremely successful in controlling serogroup C disease and continues to be evaluated. The aim of this paper is to review the experiences in England and Wales over the past 9 years.