Prevalence of meningococcal carriage among male university students living in dormitories in Kerman, southeast of Iran

Longitudinal study of meningococcal carriage in adolescents and young adults in South Australia 2017-2020

BACKGROUND

This analysis investigated longitudinal changes in meningococcal carriage in adolescents in South Australia over 4 years.

METHODS

Data from the "B Part of It" study, which included a state-wide cluster randomized controlled trial in secondary-school students (n = 34,489 in 2017 and 2018) and serial cross-sectional studies in school leavers aged 17-25 years (n = 4028 in 2019-2020). Individuals had oropharyngeal swabs collected annually. This study included two unique cohorts: (1) individuals enrolled in 2019, with three consecutive annual swabs taken in 2017, 2018 and 2019; and (2) individuals enrolled in 2020, with swabs taken in 2017, 2018, and 2020. Disease-associated N. meningitidis genogroups were identified using PCR and whole genome sequencing. Univariate analysis identified risk factors for recurrent carriage (≥2).

RESULTS

Among school leavers, 50 (1.7%, total n = 2980) had carriage detected at successive visits. In participants with meningococcal carriage at successive visits, 38/50 (76.0%) had the same genogroup detected by porA PCR. Of those, 19 had the same MLST type and demonstrated minimal variation, indicating they most likely had sustained carriage of the same isolate (range 226 to 490 days, mean duration 352 [SD 51] days). In the 2019 school leaver cohort, 6.7% acquired carriage in their first year out of school compared to 3.3% in their final school year. Compared to single carriage detection, recurrent carriage was potentially more likely in older adolescents (16 compared to ≤15 years; OR = 1.97 (95%CI 1.0, 3.86); p = 0.048).

CONCLUSION

Whilst carriage is typically transient, some adolescents/young adults may have persistent carriage and are likely to be an important group in the transmission of meningococci.

Meningococcal Disease and Immunization Activities in Hajj and Umrah Pilgrimage: a review

Invasive meningococcal disease (IMD) outbreaks associated with Hajj and Umrah pilgrimage events in the Kingdom of Saudi Arabia (KSA) are well recognized. Past outbreaks have been associated with substantial intercontinental spread of specific Neisseria meningitidis serogroups. The emergence of meningococcal serogroup W (MenW) was a global concern following the 2000/2001 Hajj outbreaks. Broader compulsory meningococcal serogroups A, C, W and Y (MenACWY) immunization strategies for pilgrims were introduced in response to these events and led to substantial declines in IMD cases associated with these mass gatherings. However, there remains potential for future outbreaks either within KSA during the Hajj or in local populations via pilgrim meningococcal transmission on their return. While the annual Hajj involves pilgrims from over 185 countries, two-thirds of these arrive from 13 countries, chiefly from across South-East Asia, the Middle East and North African (MENA) regions; for which we review the relevant epidemiology of IMD and meningococcal carriage. While disease surveillance is limited and data are often lacking, MenB is an important serogroup associated with IMD and carriage in a number of countries. Available literature suggests that most pilgrims receive polysaccharide MenACWY vaccines (which do not impact carriage and onward transmission) and incomplete compliance with visa/entry immunization regulations is reported. Existing preventative approaches for visiting pilgrims require continued oversight. More complete compliance and switching to the conjugated MenACWY vaccine can provide more robust and broader protection for pilgrims. Additional immunization options could also be considered.

Evaluation of pharyngeal carriage of Neisseria meningitidis in tehran, Iran

Meningitis and meningococcal septicemia are potentially life-threatening illnesses; young people in educational institutions have been repeatedly exposed to outbreaks of meningococcal infections. Since invasive meningococcal disease is preceded by pharyngeal carriage of Neisseria meningitidis, ascertaining the prevalence of meningococcal carriage in this population is of utmost importance. The aim of this study was to determine the rate of meningococcal carriage in students of Shahid Beheshti University of Medical Sciences. This cross-sectional study was conducted on pharyngeal swab specimens of 251 healthy asymptomatic students from November 2019 for one year. A questionnaire was used to find correlation between isolation of Neisseria spp. and the place of residence, number of roommates, antibiotic use in the last month, and smoking. One sample from each student was used for culture on general and selective culture media for Neisseria spp. Polymerase chain reaction was used for the final diagnosis of Neisseria meningitidis. Participants in the study included 222 medical students (88.4%), 23 nursing students (9.2%) and 6 radiology students (2.4%). Mean (IQR1) age of students was 23 years, 134 students were female, (53.4%); 234 students were single, (93.2%). 92 students (36.7%) lived in dormitories. Neisseria were isolated from 18 specimens (7.2%), of which 11 (4.4%) were pigmented bacteria. PCR assay did not detect Neisseria meningitidis in any of the samples. This study showed that meningococcal bacteria were not detected in any of the oropharyngeal specimens from students participating in the study during the one-year study period.

Systematic review of invasive meningococcal disease epidemiology in the Eastern Mediterranean and North Africa region

BACKGROUND

Invasive meningococcal disease (IMD) represents a global health burden. However, its epidemiology in the Eastern Mediterranean (EM) and North Africa (NA) regions is currently not well understood. This review had four key objectives: to describe asymptomatic meningococcal carriage, IMD epidemiology (e.g. serogroup prevalence, case-fatality rates [CFRs]), IMD presentation and management (e.g. clinical diagnosis, antibiotic treatments) and economic impact and evaluation (including health technology assessment [HTA] recommendations) in EM and NA.

METHODS

A systematic literature search (MEDLINE and EMBASE) was conducted (January 2000 to February 2021). Search strings included meningococcal disease and the regions/countries of interest. Identified publications were screened sequentially by title/abstract, followed by screening of the full-text article; articles were also assessed on methodological quality. Literature reviews, genetic sequencing or diagnostic accuracy studies, or other non-pertinent publication type were excluded. An additional grey literature search (non-peer-reviewed sources; start date January 2000) was conducted to the end of April 2019.

RESULTS

Of the 1745 publications identified, 79 were eligible for the final analysis (n = 61 for EM and n = 19 for NA; one study was relevant to both). Asymptomatic meningococcal carriage rates were 0-33% in risk groups (e.g. military personnel, pilgrims) in EM (no data in NA). In terms of epidemiology, serogroups A, B and W were most prevalent in EM compared with serogroups B and C in NA. IMD incidence was 0-20.5/100,000 in EM and 0.1-3.75/100,000 in NA (reported by 7/15 countries in EM and 3/5 countries in NA). CFRs were heterogenous across the EM, ranging from 0 to 57.9%, but were generally lower than 50%. Limited NA data showed a CFR of 0-50%. Data were also limited in terms of IMD presentation and management, particularly relating to clinical diagnosis/antibiotic treatment. No economic evaluation or HTA studies were found.

CONCLUSIONS

High-risk groups remain a significant reservoir of asymptomatic meningococcal carriage. It is probable that inadequacies in national surveillance systems have contributed to the gaps identified. There is consequently a pressing need to improve national surveillance systems in order to estimate the true burden of IMD and guide appropriate prevention and control programmes in these regions.

Impact of Meningococcal B (4CMenB) Vaccine on Pharyngeal Neisseria meningitidis Carriage Density and Persistence in Adolescents

BACKGROUND

Higher density of Neisseria meningitidis carriage may be associated with transmission of the meningococcus. Our aim was to establish the impact of meningococcal B (4CMenB) vaccine on N. meningitidis carriage density.

METHODS

We compared 4CMenB vaccine to control among 913 South Australian students aged approximately 15-18 years in a cluster randomized trial who had N. meningitidis carriage at 12 months. Oropharyngeal swabs were collected at baseline and 12 months later to detect N. meningitidis carriage. Colony-forming units per milliliter (CFU/mL) were estimated by generating a standard curve that plotted quantitative polymerase chain reaction cycle threshold values against log-normalized CFU.

RESULTS

Among the 913 students with N. meningitidis carriage at 12 months, there was no difference in mean carriage density between the vaccinated (n = 434; 3.80 log CFU/mL [standard deviation {SD}, 1.29]) and control group (n = 479; 3.73 log CFU/mL [SD, 1.30]; P = .51). Higher N. meningitidis carriage density at baseline was associated with an increase in the odds of persistent carriage at 12 months (n = 504; odds ratio [OR] per 1.0 log CFU/mL increase in density, 1.36 [95% confidence interval {CI}, 1.17-1.58]; P < .001). Students with baseline carriage who were vaccinated had decreased persistent N. meningitidis carriage at 12 months compared to unvaccinated students (81/260 [31%] vs 105/244 [43%]; OR, 0.60 [95% CI, .40-.90]; P = .01).

CONCLUSIONS

4CMenB vaccine did not reduce carriage density of N. meningitidis 12 months postvaccination, despite increased carriage clearance. Higher carriage density is likely to enable transmission through prolonged periods of population exposure.

CLINICAL TRIALS REGISTRATION

NCT03089086.

Risk factors for carriage of meningococcus in third-level students in Ireland: an unsupervised machine learning approach

The aim of this study was to examine the risk factors for pharyngeal carriage of meningococci in third-level students using an unsupervised machine learning approach. Data were gathered as part of meningococcal prevalence studies conducted by the Irish Meningitis and Sepsis Reference Laboratory (IMSRL). Pharyngeal swab cultures for meningococcal carriage were taken from each student once they had completed a single-page anonymous questionnaire addressing basic demographics, social behaviors, living arrangements, vaccination, and antibiotic history. Data were analyzed using multiple correspondence analysis through a machine learning approach.In total, 16,285 students who had a pharyngeal throat swab taken returned a fully completed questionnaire. Overall, meningococcal carriage rate was 20.6%, and the carriage of MenW was 1.9% (n = 323). Young Irish adults aged under 20 years and immunized with the meningococcal C vaccine had a higher MenW colonization rate (n = 171/1260, 13.5%) compared with non-Irish adults aged 20 years or older without the MenC vaccine (n = 5/81, 6%, chi-square = 3.6, p = .05). Unsupervised machine learning provides a useful technique to explore meningococcal carriage risk factors. The issue is very complex, and asked risk factors only explain a small proportion of the carriage. This technique could be used on other conditions to explore reasons for carriage.

The Burden of Invasive Vaccine-Preventable Diseases in Adults in the Middle East and North Africa (MENA) Region

Implementing vaccination programmes at the national level is key to managing vaccine-preventable diseases (VPDs) in the overall population. Although paediatric immunization programmes have significantly reduced the burden of VPD, disease burden in adults still poses a substantial challenge, particularly in low- and middle-income countries such as those within the Middle East and North Africa (MENA) region. Invasive bacterial diseases (IBDs) are an important public health concern within this region, although vaccines are available to prevent the three most common causative organisms associated with IBD: Neisseria meningitidis (NM), Streptococcus pneumoniae (SP), and Haemophilus influenzae (HI). For this review, three separate PubMed searches were used to identify English-language publications describing the epidemiology of NM, SP, and HI in adults within the MENA region. Of the 161 total publications retrieved among all 3 literature searches, 39 were included in this review (NM: 8 publications; SP: 27 publications; HI: 4 publications). Publications describing epidemiology in paediatric or overall populations were excluded. Overall, these studies generally observed a high burden of IBD among adults in this region. Although NM, SP, and HI are communicable diseases in several countries, the surveillance systems in the MENA region are largely inadequate, resulting in poor responses to outbreaks and hindering improvement in outcomes of communicable diseases. Improving IBD surveillance would provide necessary estimates of disease burden, resulting in better vaccination strategies and improved outcomes. In conclusion, the present review provides a summary of the available information on the epidemiology of vaccine-preventable IBD in adults within the MENA region and highlights the need for increased disease surveillance and preventive strategies in these countries.