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''Neisseria meningitidis'', often referred to as ''meningococcus'', is a gram negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis. The bacterium is referred to as a coccus because it is round, and more specifically, diplococcus because of its tendency to form pairs. About 10% of adults are carriers of the bacteria in their nasopharynx.〔Hitchcock P.J., Robinson E.N. (Jr.) and McGee Z.A., "Neisseriae: Gonococcus and Meningococcus", chap. 14 in Schaechter M., Medoff G. and Eisenstein B.I., ''Mechanisms of Microbial Disease'', 2th ed., Baltimore, Williams & Wilkins, 1993., p.231.〕 As an exclusively human pathogen it is the main cause of bacterial meningitis in children and young adults, causing developmental impairment and death in about 10% of cases. It causes the only form of bacterial meningitis known to occur epidemically, mainly in Africa and Asia. ''N. meningitidis'' is spread through saliva and respiratory secretions during coughing, sneezing, kissing, and chewing on toys. It infects the cell by sticking to it with long thin extensions called pili and the surface-exposed proteins Opa and Opc and has several virulence factors. ==Signs and symptoms== (詳細はmeningitis and other forms of meningococcal disease.〔 It initially produces general symptoms like fatigue, fever, and headache and can rapidly progress to neck stiffness, coma and death in 10% of cases. Symptoms of meningococcal meningitis are easily confused with those caused by other bacteria, such as ''Hemophilus influenzae'' and ''Streptococcus pneumoniae''.〔〔 Suspicion of meningitis is a medical emergency and immediate medical assessment is recommended. Current guidance in the United Kingdom is that if a case of meningococcal meningitis or septicaemia (infection of the blood) is suspected intravenous antibiotics should be given and the ill person admitted to the hospital.〔(【引用サイトリンク】title=Guidance for public health management of meningococcal disease in the UK )〕 This means that laboratory tests may be less likely to confirm the presence of ''Neisseria meningitidis'' as the antibiotics will dramatically lower the number of bacteria in the body. The UK guidance is based on the idea that the reduced ability to identify the bacteria is outweighed by reduced chance of death. Septicaemia caused by ''Neisseria meningitidis'' has received much less public attention than meningococcal meningitis even though septicaemia has been linked to infant deaths. Meningococcal septicaemia typically causes a purpuric rash, that does not lose its color when pressed with a glass ("non-blanching") and does not cause the classical symptoms of meningitis. This means the condition may be ignored by those not aware of the significance of the rash. Septicaemia carries an approximate 50% mortality rate over a few hours from initial onset. Many health organizations advise anyone with a non-blanching rash to go to a hospital as soon as possible. Not all cases of a purpura-like rash are due to meningococcal septicaemia, but other possible causes need prompt investigation as well (e.g. ITP a platelet disorder or Henoch-Schönlein purpura). Other severe complications include'' Waterhouse-Friderichsen syndrome'', a massive, usually bilateral, hemorrhage into the adrenal glands caused by fulminant meningococcemia, adrenal insufficiency, and disseminated intravascular coagulation.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Neisseria meningitidis」の詳細全文を読む スポンサード リンク
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