title: Mathematical modelling of infection and disease due to Neisseria meningitidis and Neisseria lactamica.
abstract: BACKGROUND
  Invasive meningococcal disease, due to Neisseria meningitidis, is an important cause of morbidity and mortality in young children and adolescents. Nasopharyngeal carriage of meningococci (MC), is most prevalent in young adults whereas carriage of Neisseria lactamica (LC), a related non-pathogenic organism, is most prevalent in young children. The objective of this study was to use modelling techniques to test hypotheses on the processes that govern the incidence of meningococcal disease (MD).
  
  
  METHODS
  Deterministic compartmental models were fitted to age structured data sets of MC, LC and MD.
  
  
  RESULTS
  The model most consistent with the available data sets is one where LC inhibits MC, an inhibition that lasts for a mean of 4.7 years. The hypothesis that LC also acts as a natural immunogen against MD was consistent with this model. The second peak of MD observed among adolescents could be due to the peak in the acquisition of MC in this age group.
  
  
  CONCLUSIONS
  The role of LC as a natural immunogen against asymptomatic and symptomatic meningococcal infection was consistent with available field data. If the introduction of novel meningococcal vaccines into a population changes the prevalence of MC or LC, this could have a substantial impact on the effectiveness of immunization programmes. This paper demonstrates the potential utility of modelling to estimate these effects.
authors.affiliation: Wellcome Trust Centre for Epidemiology and Infectious Disease, Zoology Department, Oxford University, UK.
authors.forename: P G
authors.initials: PG
authors.lastname: Coen
authors.forename: K
authors.initials: K
authors.lastname: Cartwright
authors.forename: J
authors.initials: J
authors.lastname: Stuart
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001530:Belgium / Q000453:epidemiology; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D006801:Humans; D015994:Incidence; D007223:Infant; D016013:Likelihood Functions; D008589:Meningococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D008875:Middle Aged; D008954:Models, Biological; D009345:Neisseria meningitidis; D015995:Prevalence