Which contacts of patients with meningococcal disease carry the pathogenic strain of Neisseria meningitidis? A population based study

Evaluating the effect of targeted strategies as control tools for hypervirulent meningococcal C outbreaks: a case study from Tuscany, Italy, 2015 to 2016

BackgroundMeningococcus (Neisseria meningitidis) is the causative bacteria of invasive meningococcal disease (IMD), a major cause of meningitis and sepsis. In 2015-16, an outbreak caused by serogroup C meningococci (MenC), belonging to the hyperinvasive strain ST-11(cc-11), resulted in 62 IMD cases in the region of Tuscany, Italy.AimWe aimed to estimate the key outbreak parameters and assess the impact of interventions used in the outbreak response.MethodsWe developed a susceptible-carrier-susceptible individual-based model of MenC transmission, accounting for transmission in households, schools, discos/clubs and the general community, which was informed by detailed data on the 2015-16 outbreak (derived from epidemiological investigations) and on the implemented control measures.ResultsThe outbreak reproduction number (Re) was 1.35 (95% prediction interval: 1.13-1.47) and the IMD probability was 4.6 for every 1,000 new MenC carriage episodes (95% confidence interval: 1.8-12.2). The interventions, i.e. chemoprophylaxis and vaccination of close contacts of IMD cases as well as age-targeted vaccination, were effective in reducing Re and ending the outbreak. Case-based interventions (including ring vaccination) alone would have been insufficient to achieve outbreak control. The definition of age groups to prioritise vaccination had a critical impact on the effectiveness and efficiency of control measures.ConclusionsOur findings suggest that there are no effective alternatives to widespread reactive vaccination during outbreaks of highly transmissible MenC strains. Age-targeted campaigns can increase the effectiveness of vaccination campaigns. These results can be instrumental to define effective guidelines for the control of future meningococcal outbreaks caused by hypervirulent strains.

The epidemiology and management of clusters of invasive meningococcal disease in England, 2010-15

BACKGROUND

Guidance for public health management of invasive meningococcal disease (IMD) in in England recommends the use of antibiotic chemoprophylaxis and vaccination. We summarized clinical and epidemiological data collected during routine management of IMD clusters in England.

METHODS

Data on epidemiology and operational decisions for public health management were reviewed for clusters between April 2010 and December 2015.

RESULTS

Clusters were generally 2-3 cases (53/58; 91%) within a single age band <18-years. Nurseries (n = 20, 34%), households/social networks (n = 14, 24%) and schools (n = 10, 17%) were the commonest settings. Chemoprophylaxis alone was used in 36 (58%) clusters, including most serogroup B clusters (31/41; 76%). Chemoprophylaxis and vaccination was used in a further 20 (32%) clusters. Vaccine was delivered promptly (<7 days). Four clusters had cases with onset post-chemoprophylaxis; no clusters recorded cases with onset post-vaccination. No pattern was observed between interventions and setting/population at risk, and interventions were consistent with national guidance. Challenges to management included logistical issues related to intervention delivery.

CONCLUSIONS

Public health management of IMD clusters presents challenges in decision-making and implementation of interventions. Nonetheless, few cases were observed following intervention. Responses were consistent with national guidance. A systematic data collection tool should be developed to support future evaluation.

Serogroup B invasive meningococcal disease (IMD) outbreak at a Japanese high school dormitory: An outbreak investigation report from the first IMD outbreak in decades

PURPOSE

The first outbreak of invasive meningococcal disease (IMD) in decades occurred in a high school dormitory in 2011. This report aims to describe the results of the IMD outbreak investigation and to discuss current issues of IMD in Japan.

METHODS

We conducted an epidemiological and microbiological investigation against the IMD outbreak of serogroup B among students and staff in a high school dormitory. Information on patients was collected to analyze risk factors for IMD. Control measures and public health actions were summarized.

RESULTS

Three cases of meningitis and two cases of bacteremia were identified. Freshmen (15-16 years old) living in the dormitory with preceding cough were high-risk populations in this outbreak. Pulsed-field gel electrophoresis, multilocus sequence typing, and porA gene sequencing results revealed that all isolates were closely related to each other and had deep similarities to the domestic circulating meningococcal strain. The outbreak was terminated after promptly implementing control measures. Based on the results of our investigation, from April 2013, national infectious disease surveillance started to target meningococcal bacteremia as part of IMD, in addition to meningococcal meningitis, which was newly designated as a category II school infectious disease under the School Health and Safety Act.

CONCLUSIONS

This outbreak has enhanced public health measures against IMD in Japan. The development of national guidelines for appropriate public health interventions on the IMD outbreak response including chemoprophylaxis is still needed.

Protocol for a controlled human infection with genetically modified Neisseria lactamica expressing the meningococcal vaccine antigen NadA: a potent new technique for experimental medicine

INTRODUCTION

Neisseria lactamica is a commensal organism found in the human nasopharynx and is closely related to the pathogen N. meningitidis (meningococcus). Carriage of N. lactamica is associated with reduced meningococcal carriage and disease. We summarise an ethically approved protocol for an experimental human challenge study using a genetically modified strain of N. lactamica that expresses the meningococcal antigen NadA. We aim to develop a model to study the role of specific bacterial antigens in nasopharyngeal carriage and immunity, to evaluate vaccines for their efficacy in preventing colonisation and to provide a proof of principle for the development of bacterial medicines.

METHODS AND ANALYSIS

Healthy adult volunteers aged 18-45 years will receive an intranasal inoculation of either the NadA containing strain of N. lactamica or a genetically modified, but wild-type equivalent control strain. These challenge volunteers will be admitted for 4.5 days observation following inoculation and will then be discharged with strict infection control rules. Bedroom contacts of the challenge volunteers will also be enrolled as contact volunteers. Safety, colonisation, shedding, transmission and immunogenicity will be assessed over 90 days after which carriage will be terminated with antibiotic eradication therapy.

ETHICS AND DISSEMINATION

This study has been approved by the Department for Environment, Food and Rural Affairs and South Central Oxford A Research Ethics Committee (reference: 18/SC/0133). Findings will be published in peer-reviewed open-access journals as soon as possible.

TRIAL REGISTRATION NUMBER

NCT03630250; Pre-results.

Invasive meningococcal disease in elderly people, New South Wales, Australia, 1993 to 2012

Little information is available publicly on invasive meningococcal disease (IMD) in elderly people in Australia. This study analysed IMD notifications data from New South Wales between 1993 and 2012 to determine the distribution of IMD among people aged 65 years and older and to describe the characteristics of IMD in this age group compared to younger age groups with respect to notification trends, serogroup distribution and mortality rates. Following introduction of a childhood vaccination programme against meningococcal type C in 2003, notification rates in all age groups decreased, but the proportion of IMD notifications in people aged 65 years and over rose significantly (from 4% to 6%, P = 0.01). Mortality rates from IMD in those aged 65 years and older were significantly higher than overall rates (32% compared to 5%, P < 0.01). Serogroup Y accounted for 23% of infections in the elderly compared to 3% in people aged under 65 years (P < 0.01). As the population ages, the elderly may account for a higher number of IMD cases in Australia. Protocols at the state and national level should be updated to provide guidance on the clinical and public health management of elderly people with IMD.

Meningococcal disease serogroup C

Despite current advances in antibiotic therapy and vaccines, meningococcal disease serogroup C (MDC) remains a serious threat to global health, particularly in countries in North and Latin America, Europe, and Asia. MDC is a leading cause of morbidity, mortality, and neurological sequelae and it is a heavy economic burden. At the individual level, despite advances in antibiotics and supportive therapies, case fatality rate remains nearly 10% and severe neurological sequelae are frequent. At the population level, prevention and control of infection is more challenging. The main approaches include health education, providing information to the public, specific treatment, chemoprophylaxis, and the use of vaccines. Plain and conjugate meningococcal C polysaccharide vaccines are considered safe, are well tolerated, and have been used successfully for over 30 years. Most high-income countries use vaccination as a part of public health strategies, and different meningococcal C vaccination schedules have proven to be effective in reducing incidence. This is particularly so with conjugate vaccines, which have been found to induce immunogenicity in infants (the age group with the highest incidence rates of disease), stimulate immunologic memory, have longer effects, not lead to hyporesponsiveness with repeated dosing, and decrease acquisition of nasopharyngeal carriage, inducing herd immunity. Antibiotics are considered a cornerstone of MDC treatment and must be administered empirically as soon as possible. The choice of which antibiotic to use should be made based on local antibiotic resistance, availability, and circulating strains. Excellent options for a 7-day course are penicillin, ampicillin, chloramphenicol, and third-generation cephalosporins (ceftriaxone and cefotaxime) intravenously, although the latter are considerably more expensive than the others. The use of steroids as adjunctive therapy for MDC is still controversial and remains a topic of debate. A combination of all of the aforementioned approaches is useful in the prevention and control of MDC, and each country should tailor its public health policy to its own particular needs and knowledge of disease burden.

What is the evidence for giving chemoprophylaxis to children or students attending the same preschool, school or college as a case of meningococcal disease?

We performed a systematic literature review to assess the effectiveness of chemoprophylaxis for contacts of sporadic cases of invasive meningococcal disease (IMD) in educational settings. No studies directly compared IMD risk in contacts with/without chemoprophylaxis. However, compared to the background incidence, an elevated IMD risk was identified in settings without a general recommendation for chemoprophylaxis in pre-schools [pooled risk difference (RD) 58·2/10⁵, 95% confidence interval (CI) 27·3-89·0] and primary schools (pooled RD 4·9/10⁵, 95% CI 2·9-6·9) in the ~30 days after contact with a sporadic IMD case, but not in other educational settings. Thus, limited but consistent evidence suggests the risk of IMD in pre-school contacts of sporadic IMD cases is significantly increased above the background risk, but lower than in household contacts (pooled RD for household contacts with no chemoprophylaxis vs. background incidence: 480·1/10⁵, 95% CI 321·5-639·9). We recommend chemoprophylaxis for pre-school contacts depending on an assessment of duration and closeness of contact.

Total antioxidant capacity of plasma in asymptomatic carrier state of Neisseria meningitidis

Reduction of the antioxidant capacity of plasma has been linked with the impairment of an effective immune response and so we hypothesized that the carriage rate of Neisseria meningitidis in asymptomatic subjects might correlate with the levels of antioxidants in plasma. To this end we took pharyngeal swabs from 339 children in Marquesado Basic Health Zone, Granada, Spain and in addition determined the total antioxidant capacity (TAC) in plasma samples from these subjects. The overall prevalence of N. meningitidis carriage was 5.9% (mean age 7.1 years) with rates of 10.3% in children aged 3 < or =years, 3.9% between 4 and 7 years and 2.4% in older subjects. Plasma TAC for the < or =3-year-olds was 0.13 for carriers and 1.10 for non-carrier controls (P=0.04), 0.13 for carriers aged 4-7 years (controls 0.63) and 0.28 for carriers aged >7 years (controls 0.52). We analysed the association between TAC in plasma (<0.37 - 2 S.D.) and the carrier state of N. meningitidis. In the carrier state, the odds ratio for this association (TAC in plasma <0.25) was 8.44 (95% CI 1.5-48.9). These findings may suggest a reduced immune response in the host favourable to nasopharyngeal persistence of meningococci.

Development of immunity to serogroup B meningococci during carriage of Neisseria meningitidis in a cohort of university students

Understanding the basis of protective immunity is a key requirement for the development of an effective vaccine against infection with Neisseria meningitidis of serogroup B. We have conducted a longitudinal study into the dynamics of meningococcal acquisition and carriage in first-year university students. The detection of carriage of serogroup B meningococci correlated with an increase in detection of serum bactericidal activity (SBA) against both colonizing and heterologous serogroup B strains. Once induced, SBA remained high throughout the study. Although students showed increases in antibodies reactive with capsular polysaccharide and lipopolysaccharide (LPS), these antibody responses were transitory, and their decline was not accompanied by a corresponding decline in SBA. In contrast, there was a significant correlation between the presence of antibodies to the PorA outer membrane protein and SBA against both homologous and heterologous strains. SBA induced by a PorA-negative mutant confirmed the contribution of PorA to heterologous activity. Increases in SBA against a range of serogroup B strains were also observed in students in whom no meningococcal carriage was detected. This heterologous protection could not be associated with the presence of antibodies reacting with capsule, LPS, PorA, PorB, Rmp, Opa, Opc, or pilin, demonstrating that other, as yet unidentified, antigens contribute to the development of immunity to serogroup B meningococci. Identification of such antigens with the ability to induce an effective cross-reactive bactericidal response to a range of strains would be a major step in the production of a universally effective vaccine against infections caused by serogroup B meningococci.

Fusidic acid resistance in community isolates of methicillin susceptible Staphylococcus aureus and the use of topical fusidic acid: a retrospective case-control study

Resistance to fusidic acid among community methicillin susceptible Staphylococcus aureus (MSSA) isolates in the United Kingdom and prescriptions for fusidic acid have both doubled over the past 6 years. A retrospective case-control study was undertaken to test the hypothesis that the use of topical fusidic acid is associated with the isolation of resistant organisms. A statistically significant association was found between fusidic acid resistance in MSSA isolates and exposure to topical fusidic acid (odds ratio: 2.77, 95% CI 1.01-7.93, P = 0.027). This study demonstrates for the first time an association between the use of topical fusidic acid and resistance at the individual patient level and supports the hypothesis that the observed increase in resistance is causally associated with the increased use of topical fusidic acid.

Risk and prevention of meningococcal disease among education workers: A review

The aims of the present study were to review the risk of invasive meningococcal disease (IMD) among education workers, particularly pregnant women, and to evaluate preventive measures, in a context of endemicity, outbreak or epidemic as observed in the province of Quebec. The literature was reviewed and persons in charge of IMD surveillance in France, Quebec, the United Kingdom and the United States were interviewed. Surveys of asymptomatic carriage of Neisseria meningitidis show that transmission among students is higher than transmission between students and teachers. IMD incidence among education workers was analyzed in Cheshire (United Kingdom) in the period from 1997 to 1999, and the results indicated a risk six times higher than that in the general population. Overestimation of the magnitude of the risk is possible because the analysis focused on a cluster. None of the population-based studies of IMD mentioned a risk of secondary cases among education workers. Six IMD cases in education workers were identified in five clusters in schools in the United Kingdom, but not in the other countries. There is no epidemiological study on IMD risk among pregnant women, and this factor was not mentioned in any published review of IMD. Immunization of education workers at the beginning of their employment, using serogroup C glycoconjugate vaccine or a combined A, C, W-135, and Y conjugate vaccine (still under development), could reduce IMD risk, but the cost effectiveness of this measure should be evaluated. The societal benefit of excluding pregnant women from the work place during an outbreak seems to be very low, even if disease risk could be decreased for this specific group. When chemoprophylaxis is indicated for the control of an outbreak in an educational setting, treatment should be offered both to students and teachers in the group at risk.

Mass vaccination campaign following community outbreak of meningococcal disease

During December 12-29, 1998, seven patients ages 2-18 years were diagnosed with serogroup C meningococcal disease in two neighboring Florida towns with 33,000 residents. We evaluated a mass vaccination campaign implemented to control the outbreak. We maintained vaccination logs and recorded the resources used in the campaign that targeted 2- to 22-year-old residents of the two towns. A total of 13,148 persons received the vaccinations in 3 days. Vaccination coverage in the target population was estimated to be 86% to 99%. Five additional cases of serogroup C meningococcal disease occurred in the community during the year after the campaign began, four in patients who had not received the vaccine. The cost of control efforts was approximately $370,000. Although cases continued to occur, the vaccination campaign appeared to control the outbreak. Rapid implementation, a targeted approach, and high coverage were important to the campaign's success.

Mass vaccination campaign following community outbreak of meningococcal disease

During December 12-29, 1998, seven patients ages 2-18 years were diagnosed with serogroup C meningococcal disease in two neighboring Florida towns with 33,000 residents. We evaluated a mass vaccination campaign implemented to control the outbreak. We maintained vaccination logs and recorded the resources used in the campaign that targeted 2- to 22-year-old residents of the two towns. A total of 13,148 persons received the vaccinations in 3 days. Vaccination coverage in the target population was estimated to be 86% to 99%. Five additional cases of serogroup C meningococcal disease occurred in the community during the year after the campaign began, four in patients who had not received the vaccine. The cost of control efforts was approximately $370,000. Although cases continued to occur, the vaccination campaign appeared to control the outbreak. Rapid implementation, a targeted approach, and high coverage were important to the campaign's success.

Carriers of Neisseria meningitidis in household contacts of meningococcal disease cases in Catalonia (Spain)

A population-based study was carried out in Catalonia (Spain) from May 1998 to April 1999 to determine the prevalence of Neisseria meningitidis strains in meningococcal disease (MD) cases and their contacts, as well as the prevalence of meningococci in close contacts of patients with MD, and risk factors for its carriage. A total of 364 close contacts of 87 patients with MD were studied. Throat samples were collected by hospital staff before rifampicin chemoprophylaxis was begun. For each contact, a questionnaire was completed for sociodemographic and epidemiological data. A total of 61 contacts (an overall prevalence of 16.8%) were carriers of meningococcal strains (40 B, 10 C, 1 Z and 10 non-groupable isolates). This prevalence is two to three times higher than in the general population (5-10%). In 33/61 microbiologically confirmed cases (54%) and in 9/26 probable cases (35%), contacts carrying N. meningitidis were found. In 22/33 confirmed cases with carrier contacts, it was possible to study the phenotype of the carrier and patient strains (sero-group, serotype and serosubtype). In 14 cases (64%), both strains were identical, in four cases, only a minor change was observed, in three cases, some strain (from the case or from his contact) was non-serotypable and non-serosubtypable, and in one case, both isolates were completely different. Bivariate analysis identified five statistically significant risk factors for meningococcal carriage: age (5-9 years old), meningococcal A+C vaccination, severe household overcrowding, social class and heavy active smoking (>20 cigarettes a day). Multivariate analysis revealed that of these five variables, only heavy active smoking remained statistically significant when the other factors were controlled.

Variations in chemoprophylaxis for meningococcal disease: a retrospective case note review, analysis of routine prescribing data and questionnaire of general practitioners

BACKGROUND

Invasive meningococcal disease is a significant cause of mortality and morbidity in the UK. Administration of chemoprophylaxis to close contacts reduces the risk of a secondary case. However, unnecessary chemoprophylaxis may be associated with adverse reactions, increased antibiotic resistance and removal of organisms, such as Neisseria lactamica, which help to protect against meningococcal disease. Limited evidence exists to suggest that overuse of chemoprophylaxis may occur. This study aimed to evaluate prescribing of chemoprophylaxis for contacts of meningococcal disease by general practitioners and hospital staff.

METHODS

Retrospective case note review of cases of meningococcal disease was conducted in one health district from 1st September 1997 to 31st August 1999. Routine hospital and general practitioner prescribing data was searched for chemoprophylactic prescriptions of rifampicin and ciprofloxacin. A questionnaire of general practitioners was undertaken to obtain more detailed information.

RESULTS

Prescribing by hospital doctors was in line with recommendations by the Consultant for Communicable Disease Control. General practitioners prescribed 118% more chemoprophylaxis than was recommended. Size of practice and training status did not affect the level of additional prescribing, but there were significant differences by geographical area. The highest levels of prescribing occurred in areas with high disease rates and associated publicity. However, some true close contacts did not appear to receive prophylaxis.

CONCLUSIONS

Receipt of chemoprophylaxis is affected by a series of patient, doctor and community interactions. High publicity appears to increase demand for prophylaxis. Some true contacts do not receive appropriate chemoprophylaxis and are left at an unnecessarily increased risk.

Meningococcal infections and meningitis: what is new?

Meningococcal infection is one of the very few severe bacterial infections, in this era, that still can kill a relatively healthy child within minutes. Fortunately, it is a relatively rare disease. Rural practitioners may see one affected child once every 2-3 years, but once seen they will never forget it. The present article gives some examples of case scenarios along with a brief overview of the problem, with emphasis on early diagnosis, prevention and possible future developments.

Management and prevention of meningococcal disease

While many other illnesses affecting children have been contained or even eliminated, meningococcal disease has become a leading infectious cause of death. The major management challenge may be increased intracranial pressure or toxic shock, depending on whether meningitis or septicemia predominates. A new protein-conjugated group C vaccine is expected to reduce deaths by as much as 40%.

Prophylaxis of bacterial meningitis

A comprehensive review of all major agents causing bacterial meningitis--meningococcus of the groups A, B, C, W135, and Y, pneumococcus, and Haemophilus influenzae type B (Hib)--is done in terms of preventing them by chemoprophylaxis or vaccination. Some evidence suggests that the group B meningococcal disease may also be very likely preventable by a vaccine that is already available. Excellent Hib conjugates use a technique that is expected to revolutionize immunoprophylaxis against most meningococcal and pneumococcal diseases in the near future. Unfortunately, the high cost of conjugate vaccines restricts their use in many poor countries.