Meningococcal disease: has the battle been won?

National and regional differences in meningococcal vaccine recommendations for individuals at an increased risk of meningococcal disease

INTRODUCTION

Invasive meningococcal disease (IMD) is a severe, life-threatening condition caused by infection with Neisseria meningitidis. Currently available vaccines offer protection against the five most common meningococcal disease-causing serogroups and include monovalent and quadrivalent conjugate vaccines (MenA, MenC, MenACWY vaccines) and outer membrane vesicle- and/or recombinant protein-based vaccines (MenB vaccines).

AREAS COVERED

Country and regional immunization programs target populations susceptible to IMD and typically emphasize the highest-risk age groups (i.e., infants, adolescents/young adults, and the elderly); however, additional groups are also considered at an elevated risk and are the focus of the current review. Specific increased-risk groups include individuals with underlying immunocompromising medical conditions, university/college students, Indigenous people, laboratory workers, military personnel, men who have sex with men, and travelers to areas with hyperendemic IMD. This review compares established meningococcal vaccination recommendations for these vulnerable groups in Europe, the United States, Australia, New Zealand, Israel, Brazil, and Turkey.

EXPERT OPINION

Recommendations should be standardized to cover all groups at increased risk of IMD.

A Historical Review of Military Medical Strategies for Fighting Infectious Diseases: From Battlefields to Global Health

The environmental conditions generated by war and characterized by poverty, undernutrition, stress, difficult access to safe water and food as well as lack of environmental and personal hygiene favor the spread of many infectious diseases. Epidemic typhus, plague, malaria, cholera, typhoid fever, hepatitis, tetanus, and smallpox have nearly constantly accompanied wars, frequently deeply conditioning the outcome of battles/wars more than weapons and military strategy. At the end of the nineteenth century, with the birth of bacteriology, military medical researchers in Germany, the United Kingdom, and France were active in discovering the etiological agents of some diseases and in developing preventive vaccines. Emil von Behring, Ronald Ross and Charles Laveran, who were or served as military physicians, won the first, the second, and the seventh Nobel Prize for Physiology or Medicine for discovering passive anti-diphtheria/tetanus immunotherapy and for identifying mosquito Anopheline as a malaria vector and plasmodium as its etiological agent, respectively. Meanwhile, Major Walter Reed in the United States of America discovered the mosquito vector of yellow fever, thus paving the way for its prevention by vector control. In this work, the military relevance of some vaccine-preventable and non-vaccine-preventable infectious diseases, as well as of biological weapons, and the military contributions to their control will be described. Currently, the civil-military medical collaboration is getting closer and becoming interdependent, from research and development for the prevention of infectious diseases to disasters and emergencies management, as recently demonstrated in Ebola and Zika outbreaks and the COVID-19 pandemic, even with the high biocontainment aeromedical evacuation, in a sort of global health diplomacy.

Mass gatherings: a review of the scope for meningococcal vaccination in the Indian context

The risk of meningococcal transmission is increased with crowding and prolonged close proximity between people. There have been numerous invasive meningococcal disease (IMD) outbreaks associated with mass gatherings and other overcrowded situations, including cramped accommodation, such as student and military housing, and refugee camps. In these conditions, IMD outbreaks predominantly affect adolescents and young adults. In this narrative review, we examine the situation in India, where the burden of IMD-related complications is significant but the reported background incidence of IMD is low. However, active surveillance for meningococcal disease is suboptimal and laboratory confirmation of meningococcal strain is near absent, especially in non-outbreak periods. IMD risk factors are prevalent, including frequent mass gatherings and overcrowding combined with a demographically young population. Since overcrowded situations are generally unavoidable, the way forward relies on preventive measures. More widespread meningococcal vaccination and strengthened disease surveillance are likely to be key to this approach.

Retrospective analysis of the etiology, clinical characteristics and outcomes of community-acquired bacterial meningitis in the University Infectious Diseases Centre in Lithuania

Background

The morbidity and mortality in community-acquired bacterial meningitis (CABM) remain substantial, and the etiology, clinical characteristics, treatment outcomes and predictors of poor prognosis must be assessed regularly. The aim of this study was to identify the distribution of etiological agents and their relationship with clinical characteristics, treatment and outcomes in this cohort of patients with CABM.

Methods

Our retrospective chart review analyzed the causative microorganisms, clinical characteristics, laboratory findings, treatment and outcomes of 159 adults with CABM hospitalized in the Infectious Diseases Centre of Vilnius University Hospital from January 1, 2009 to December 31, 2016. A Glasgow Outcome Scale (GOS) score ≤ 3 was defined as unfavorable outcome. Predictors of an unfavorable outcome were identified through logistic regression analysis.

Results

The median patient age was 36 (IQR 24–56), and 51.6% were male. Microbiologically confirmed causative agents were identified in 80 (50.3%) patients: N. meningitidis in 55 (34.6%) patients with serotype B accounting for 85% of cases, S. pneumoniae in 15 (9.4%), L. monocytogenes in 5 (3.1%) and other in 5 (3.1%). The clinical triad of fever, neck stiffness and a change in mental status was present in 59.1% of patients. Coexisting conditions and comorbidities were similar in all groups stratified by etiology. Initial antimicrobial treatment consisted of penicillin in 78 patients (49.1%) and ceftriaxone in 72 patients (45.3%). The median time in which antibiotic treatment was started was 40 min (IQR 30.0–90.0). The outcome was unfavorable in 15.7% of episodes and death occurred in 5.7% of cases and did not differ according to the causative agent. Risk factors for an unfavorable outcome were age > 65 years, coexisting pneumonia and a platelet count <150x10e9/l.

Conclusions

The most common causative agent of CABM was N. meningitidis, with serotype B clearly dominant. Causative agents did not influence the disease outcome. The strongest risk factors for an unfavorable outcome were older age, pneumonia and a low platelet count. Since the introduction of routine vaccination against meningococcus B for infants in Lithuania in 2018, the national vaccination policy may hopefully contribute to a decrease in the incidence of serogroup B meningococcal disease in the Lithuanian population.

Evaluation of Neisseria meningitidis Carriage with the Analysis of Serogroups, Genogroups and Clonal Complexes among Polish Soldiers

Neisseria meningitidis is an etiological factor of invasive meningococcal disease (IMD). This Gram-negative diplococcus is transmitted from person to person via droplets or through a direct physical contact with secretions of infected patients or asymptomatic carriers. The latter account for 5–10% of the general population. The aim of the study was to estimate the actual N. meningitidis carriage rate in the military environment with identification of serogroups, genogroups, sequence types and clonal complexes of the isolates detected among Polish soldiers. The study was conducted during winter seasons of 2015 and 2016 and involved 883 professional soldiers from the Armoured Brigade in Świętoszów, Poland. The material for testing were nasopharyngeal swabs obtained from study participants. The samples were tested using standard microbiological methods (culture, incubation, microscopy, biochemical and automated identification). N. meningitidis isolates were subjected to slide agglutination test (identification of serogroups), the bacterial DNA was extracted and allowed to determine genogroups, clonal complexes and sequence types. 76 soldiers were found to be carriers of N. meningitidis, they accounted for 8.6% of the study group. The meningococcal isolates mostly belonged to serogroup B. Sequence types ST-11439, ST-136, ST-1136 and the clonal complex 41/44CC were found to be predominant. Clonal complexes responsible for IMD were detected in 15.8% of carriers and 1.4% of the whole study participants. Carriage rates of N. meningitidis among Polish soldiers were found to be similar to those reported in the general population.

Treatment of military cases of cerebrospinal fever during WWI: the concerted efforts of the RAMC, MRC and Lister Institute to make serum therapy work

Cerebrospinal fever was rare in the British Army prior to World War I. An outbreak of the disease on Salisbury Plain in late 1914 posed new challenges. The War Office established the Central Cerebrospinal Fever Laboratory at the Royal Army Medical (RAM) College early in 1915 to conduct research, develop diagnostic tests and coordinate the military response. The Royal Army Medical Corps (RAMC) set up dedicated cerebrospinal wards for the hospitalisation and treatment of patients. The new Medical Research Committee (MRC) supported bacteriological studies of epidemic strains of the meningococcus responsible for the outbreak. The Lister Institute of Preventive Medicine, an independent research institution, acted as a key supplier of antimeningococcus serum. The mortality of military patients during 1915 was poor because the testing infrastructure was still developing, the RAMC had limited experience of treating cases, and the therapeutic serums available at the time seemed ineffective. The survival rate of home troops improved during the war-through the concerted efforts of the RAMC, MRC and Lister Institute-due to timely diagnosis, and early, intensive and prolonged treatment with improved serums. The Official History of the War highlights subsequent trials undertaken with strain-specific MRC serums in late 1918 and 1919 but fails to acknowledge that in late 1917/early 1918 the Lister Institute supplied the RAM College with large quantities of an efficacious multivalent serum and corresponding monovalent serums that were not included in a formal trial.

Waning Immunity and Microbial Vaccines-Workshop of the National Institute of Allergy and Infectious Diseases

Since the middle of the 20th century, vaccines have made a significant public health impact by controlling infectious diseases globally. Although long-term protection has been achieved with some vaccines, immunity wanes over time with others, resulting in outbreaks or epidemics of infectious diseases. Long-term protection against infectious agents that have a complex life cycle and antigenic variation remains a key challenge. Novel strategies to characterize the short- and long-term immune responses to vaccines and to induce immune responses that mimic natural infection have recently emerged. New technologies and approaches in vaccinology, such as adjuvants, delivery systems, and antigen formulations, have the potential to elicit more durable protection and fewer adverse reactions; together with in vitro systems, these technologies have the capacity to model and accelerate vaccine development. The National Institute of Allergy and Infectious Diseases (NIAID) held a workshop on 19 September 2016 that focused on waning immunity to selected vaccines (for Bordetella pertussis, Salmonella enterica serovar Typhi, Neisseria meningitidis, influenza, mumps, and malaria), with an emphasis on identifying knowledge gaps, future research needs, and how this information can inform development of more effective vaccines for infectious diseases.