Other strains include 29-E, H, I, K, L, and Z.
Suspicion of meningitis is a medical emergency and immediate medical assessment is recommended. Current guidance in the United Kingdom is that any doctor who suspects a case of meningococcal meningitis or septicaemia (infection of the blood) should give intravenous antibiotics (benzylpenicillin or Cefotaxime) and admit the ill person to the hospital. 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 turn white 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 emergency room as soon as possible. Note that not all cases of a purpura-like rash are due to meningococcal septicaemia; however, other possible causes need prompt investigation as well (e.g. ITP a platelet disorder or Henoch-Schönlein purpura).
If the organism reaches the circulation, then blood cultures should be drawn and processed accordingly.
Quintain NS and RMIT University have developed a rapid diagnostic test for meningococcal disease, which will ultimately provide results in under 15 minutes.
Clinical tests that are used currently for the diagnosis of meningococcal disease take between 2 and 48 hours and often rely on the culturing of bacteria from either blood or cerebrospinal fluid (CSF) samples. As the disease has a fatality risk approaching 15% within 12 hours of infection, early diagnosis and antibiotic treatment is crucial.
Quintain is working with Melbourne-based company Charlwood Design, to produce a prototype clinical device that will incorporate a mechanism for safe sample handling and delivery. It is expected that the diagnostic test will be available within 2-3 years, with the nanoparticulate gold diagnostic platform adapted for a range of other clinically important diseases shortly thereafter.
Neisseria meningitidis has 13 clinically significant serogroups. These are classified according to the antigenic structure of their polysaccharide capsule. Five serogroups, A, B, C, Y and W135 are responsible for virtually all cases of the disease in humans. There is currently no effective vaccine for serogroup B, although a putative vaccine is currently undergoing clinical trials in New Zealand.
The two quadrivalent (i.e., targeting serogroups A, C, W-135 and Y) meningococcal vaccines available in the US are MCV-4 (a conjugate vaccine Menactra manufactured by Sanofi Pasteur introduced in January 2005) and MPSV-4 (a polysaccharide vaccine marketed as Menomune, also by Sanofi Pasteur).
Menomune has a number of problems. The duration of action is short (3 years or less in children aged under 5), because it does not generate memory T-cells. Attempting to overcome this problem by repeated immunisation results in a diminished, not increased antibody response, so boosters are not indicated with this vaccine. In common with all polysaccharide vaccines, Menomune does not produce mucosal immunity, so people can still become colonised with virulent strains of meningococcus, and no herd immunity develops. For this reason, Menomune is eminently suitable for travellers requiring only short term protection, but has no place in national public health programmes.
Menactra contains the same antigens as Menomune, but the antigens are conjugated to diphtheria toxoid. It is hoped that this formulation will overcome the limitations of Menomune. Menactra is currently licensed only for use in people aged 11 to 55, therefore people outside of this age group can only be offered Menomune.
A study published in March 2006 comparing the two vaccines found that 76% of subjects still had passive protection three years after receiving MCV-4 (63% protective compared with controls), but only 49% has passive protection after receiving MSPV-4 (31% protective compared with controls). This has implications for the timing of recommendations for when meningococcal vaccines should be given, because there is currently no evidence that any of the current vaccines offer continued protection beyond three years.