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Outbreaks of Neisseria meningitidis serotype B infection

Carole Moloney, RN, MSN, CPNP

Approximately 21% of all meningococcal disease cases occur in preteens, teens, and young adults aged 11-24 years, according to the Centers for Disease Control and Prevention. Certain lifestyle factors among teens appear to contribute to their increased risk, including living conditions in college dormitories, attendance at a new school with students from geographically diverse areas, irregular sleeping patterns, smoking or exposure to passive smoking, and social situations in which there is overcrowding.


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Importance of antibodies

All vaccines against N. meningitidis work by the induction of antibodies in serum. Transudation from serum may block adherence of the bacteria to epithelial cells in the nasopharynx to prevent contagion spread and provide herd immunity. Serum bactericidal antibody levels of greater than or equal to 1:4 correlate with protection. However, a specific level of antibody is not an absolute correlate of protection for every person because there is genetic variation in susceptibility to disease, there can be differences in virulence among strains, there can be differences in innate immune responses among individuals, there can be variation in the inoculum of the pathogen, and there may be effects from concurrent illness or coinfection. Therefore, a specified protective level of antibody should be considered as a close estimate applicable in the majority of potentially susceptible persons.

Antibody levels usually decline over time after vaccination if boosters are not given, although there are exceptions. Persistence of vaccine-induced antibodies usually goes well beyond the time when antibodies should have disappeared according to the mathematics of their half-life. This may be caused by ongoing “natural” boosting or other immunologic mechanisms. Natural boosting can occur by asymptomatic colonization by the pathogen or by a nonpathogen expressing a cross-reactive antigen. Natural boosting can decrease over time as a pathogen circulates less widely in a population because of increasing use of a vaccine and/or the establishment of herd immunity. This is an ongoing issue relative to several vaccines because the absence of natural boosting among vaccinees may lead to a return to disease susceptibility.

Certain lifestyle factors among teens appear to contribute to their increased risk, including living conditions in college dormitories, attendance at a new school with students from geographically diverse areas, irregular sleeping patterns, smoking or exposure to passive smoking, and social situations in which there is overcrowding.

Outbreaks of serogroup B meningococcal disease occurred on 20 college campuses from March 2013 to November 2017. These outbreaks included those at Princeton (N.J.) University, Santa Clara (Calif.) University, the University of Oregon in Eugene, Providence (R.I.) College, and the University of California, Santa Barbara.

Watch our video with Robin Izzo, director of environmental health and safety at Princeton University, who talked with us about the outbreak at her school.