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Meningococcal disease information sheet

Meningococcal meningitis and meningococcal septicaemia are systemic infections caused by the bacteria Neisseria meningitidis (also known as the meningococcus) Humans are the only known reservoir for Neisseria meningitidis.

Neisseria meningitidis is commonly found in the back of the throat or nose and will only occasionally cause disease. It is unknown why some individuals carry the bacteria without them causing harm while others go on to develop meningococcal disease. Approximately 10% of the population will carry Neisseria meningitidis, with the highest carriage (around 25%) in adolescents and young adults. Infection is transmitted from person to person by inhaling respiratory secretions from the mouth and throat or by direct contact (e.g. kissing). Close prolonged contact is usually required to transmit these bacteria which do not live long outside the body.

Meningococcal bacteria are classified into 13 different serogroups, based on the kind of polysaccharide capsule (sugar coating) that surrounds the bacteria. Only 5 serogroups are known to cause disease in the UK: A, B, C, W135 and Y.

In an educational setting a cluster is defined as two or more cases of meningococcal disease occurring in the same pre-school group, school, or college/university within a four week period:

  • If two possible cases attend the same institution, whatever the interval between cases, prophylaxis to any contacts is not indicated.
  • If two confirmed cases caused by different strains attend the same institution, they should be regarded as two sporadic cases, whatever the interval between them. Only close contacts, such as household members, of each case should be offered prophylaxis.
  • If two confirmed/probable cases who attend the same preschool group, school, college or university arise within a four-week period and are, or could be, caused by the same serogroup, public health action is indicated that may involve prophylaxis of a wider group than close contacts of each case. It is not necessary to wait for microbiological results on probable cases (high immediate risk of further cases).

    www.hpa.org.uk with additions marked in italics

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