External quality assurance scheme for Neisseria meningitidis 2012
Neisseria meningitidis is the major worldwide cause of meningitis and rapidly fatal sepsis in healthy individuals. The risk of meningococcal disease is higher among those with complement deficiencies, asplenia and other underlying conditions. N. meningitidis is the only agent among the major bacterial agents causing meningitis that may cause epidemic as well as endemic disease. The meningococcus is carried in the human nasopharynx asymptomatically by 5% to 10% of adults in non-epidemic periods but may be greater than 30% for first-year university students. N. meningitidis accounts for... morbidity and mortality within the cases and may result in sequelae. In addition, it may be responsible for more unusual presentations, such as arthritis, osteomyelitis and cellulitis. Meningococci are characterised using serologic typing systems based on structural differences of the polysaccharide capsule (serogroup), major outer membrane protein porin B (serotype), major outer membrane protein porin A (sero-subtype) and lipooligosaccharide (immunotype). Molecular-based typing of meningococci has revealed genetically related strains (described as clonal complexes) that cause most disease, some of which (e.g. cc ST-11) show particular epidemiological features: relatively low carriage, rapid transmissibility and raised casefatality ratio. Meningococcal disease surveillance is paramount and aims at different targets: early detection of cases to activate public health response (namely identification of close contacts and administration of chemoprophylaxis to prevent secondary cases of the disease, to evaluate trends, and to act in outbreaks), surveillance for vaccination purposes, and the estimation of the burden of meningococcal disease. Meningococcal surveillance systems are partially based on laboratory diagnoses; therefore, there is a need for accuracy and proficiency in surveillance laboratory performance.