Abstract
Teenagers have a higher risk of invasive meningococcal disease (IMD) than the general population. This cross-sectional study aimed to characterise strains of Neisseria meningitidis circulating among Norwegian teenagers and to assess risk factors for meningococcal carriage. Oropharyngeal swabs were collected from secondary-school students in southeastern Norway in 2018-2019. Meningococcal isolates were characterised using whole genome sequencing. Risk factors for meningococcal carriage were assessed from questionnaire data. Samples were obtained from 2296 12-24-year-olds (majority 13-19-year-olds). N. meningitidis was identified in 167 (7.3%) individuals. The highest carriage rate was found among 18-year-olds (16.4%). Most carriage isolates were capsule null (40.1%) or genogroup Y (33.5%). Clonal complexes cc23 (35.9%) and cc198 (32.3%) dominated and 38.9% of carriage strains were similar to invasive strains currently causing IMD in Norway. Use of Swedish snus (smokeless tobacco) (OR 1.56, 95% CI 1.07-2.27), kissing >two persons/month (OR 2.76, 95% CI 1.49-5.10) and partying >10 times/3months (OR 3.50, 95% CI 1.45-8.48) were associated with carriage, while age, cigarette smoking, sharing of drinking bottles and meningococcal vaccination were not. The high meningococcal carriage rate among 18-year-olds is probably due to risk-related behaviour. Use of Swedish snus is possibly a new risk factor for meningococcal carriage. Almost 40% of circulating carriage strains have invasive potential.
Highlights
Invasive meningococcal disease (IMD) is caused by Neisseria meningitidis, the meningococcus
The aims of this study were to investigate the prevalence of meningococcal carriage in Norwegian teenagers, to characterise circulating carriage strains of N. meningitidis and to identify risk factors for meningococcal carriage in this age group
For the evaluation of differences between closely related invasive-carrier clusters, we evaluated all allelic differences across the 3050 loci defined in PubMLST at the time of analysis (November 2019)
Summary
Invasive meningococcal disease (IMD) is caused by Neisseria meningitidis, the meningococcus. Despite improved treatment and the development of effective vaccines, mortality remains high even in high-income countries. Many surviving patients suffer sequelae such as skin scarring, limb amputation, hearing loss or learning disabilities [1]. Meningococci are classified into 12 serogroups based on the structure of the polysaccharide capsule. IMD is usually caused by serogroups A, B, C, W, X or Y, which all have epidemic potential. Uncapsulated meningococci seldom cause invasive disease, but are commonly detected in the oropharynx in healthy individuals [2]
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