Social Behavior and Meningococcal Carriage in British Teenagers

Abstract

Understanding predisposing factors for meningococcal carriage may identify targets for public health interventions.Before mass vaccination with meningococcal group C conjugate vaccine began in autumn 1999, we took pharyngeal swabs from ≈14,000 UK teenagers and collected information on potential risk factors.Neisseria meningitidis was cultured from 2,319 (16.7%) of 13,919 swabs.In multivariable analysis, attendance at pubs/clubs, intimate kissing, and cigarette smoking were each independently and strongly associated with increased risk for meningococcal carriage (p<0.001).Carriage in those with none of these risk factors was 7.8%, compared to 32.8% in those with all 3. Passive smoking was also linked to higher risk for carriage, but age, sex, social deprivation, home crowding, or school characteristics had little or no effect.Social behavior, rather than age or sex, can explain the higher frequency of meningococcal carriage among teenagers.A ban on smoking in public places may reduce risk for transmission.P haryngeal carriage of Neisseria meningitidis, however brief, is a prerequisite for invasive meningococcal disease.Highest age-specific disease attack rates are seen in young infants.Another peak of disease that is accompanied by higher frequency of pharyngeal carriage is seen in teenagers (1).N. meningitidis may be cultured from the pharynx in as many as 1 in 4 teenagers (2).Male sex (2-5), cigarette smoking (6-8), passive exposure to smoke (8), bar patronage, discotheque visits (9), antimicrobial drug use (9,10), kissing (5), and overcrowding (11) have been associated with carriage, and many of these factors are also risk factors for meningococcal disease (12-15).Outbreaks of meningococcal disease are well documented in educational institutions ( 16), but no data exist on institutional factors that might contribute to carriage and transmission of meningococci.Social deprivation is associated with meningococcal disease ( 17), but whether it is associated with carriage is unknown.Greater knowledge of risk factors for meningococcal carriage may help to identify useful public health interventions.In 1999, meningococcal group C conjugate vaccine (MenC) was offered to all persons <18 years of age in the United Kingdom (18).We identified risk factors for carriage among 14,000 teenagers as an integral part of a large, 3-year, multicenter study to determine the effect of this mass vaccination program on the carriage of meningococci.A reduction in serogroup C carriage after this intervention has already been reported (19).The study size gave us high statistical power to investigate the independent effects of risk factors at both individual and school levels.