什么is meningococcal disease?
脑膜炎球菌病是一种illness caused by thebacteriaNeisseria meningitidis. The two common presentations of meningococcalinfectionare meningococcalmeningitis(infection of the membranes that surround the brain and spinalcord) and meningococcemia (infection of the bloodstream). An infected individual may suffer one or both of these diseases.
Meningococcal disease is a medical emergency and patients showing signs and symptoms suspicious of meningococcal infection need to seek medical advice from their doctor or a hospital immediately. A delay of even hours can be fatal. There are several deaths from meningococcal disease every year in New Zealand and even more duringepidemics.
最常见的cutaneoussignof meningococcal disease islocalisedacralpurpura.
Purpura due to meningococcal disease
How do you get meningococcal disease?
Neisseria meningitidisbacteria are spread from person to person by inhaling airborne droplets when an infected person coughs or sneezes or just by close contact.
In many cases, the bacteria is spread by infected individuals that arecarriersofNeisseria meningitidisbut do not show any symptoms.Neisseria meningitidisis present in the nose and throat of these individuals, but the body's natural defence mechanisms contain the infection by producingantibodiesagainst the bacteria so that spread to other parts of the body is prevented.Carrierrates depend on age and the highest rate is found in young adults (15-24 years) at 20-40%.
Rarely, exposure toNeisseria meningitidiswill lead to meningococcal disease where bacteria spreads to the blood and brain, causing meningococcemia and/or meningococcal meningitis. This may occur if the body has not had enough time to build up anantibodydefence or in those with defective immune systems.
Who is at risk of meningococcal disease?
Most patients with meningococcal disease are otherwise healthy individuals. However, there are some patient groups who are at an increased risk fordevelopinga meningococcal infection.
- Children 6 months to 4 years: until about 6 months immunity from the mother is present. Beyond 4 years many children have developed immunity to many strains ofNeisseria meningitidis.
- Individuals withcomplementdeficiencies.Complementis a part of the immune system required for the breakdown of meningococcal bacteria.
- Individuals without spleens (asplenic).
- Individuals takingimmunosuppressivedrugs such asprednisone或ciclosporin.
- Individuals with a current viral infection.
什么are the signs and symptoms of meningococcal disease?
最常见的signs and symptoms of meningococcal disease are listed in the table below.
If an individual has both meningococcal meningitis and meningococcemia, they may present with a mixture of symptoms and signs characteristic to each of the diseases.
| Signs and symptoms of meningococcal disease | |
| Meningococcal meningitis | Meningococcemia |
Children >1 year and adults
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Signs on the skin
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Purpura due to meningococcal disease
How is meningococcal disease diagnosed?
Meningococcal meningitis and meningococcemia is often suspected from the history and physical examination. Bloodcultureand/or lumbar puncture are used to confirm the diagnosis. A lumbar puncture involves putting a needle in the lower back to obtain some cerebrospinal fluid (CSF). An increased number of white cells are seen under themicroscope, with meningitis confirmed when theleukocytecount in the CSF is > 5 cells/µL (bacterialmeningitis often has >1000 cells/µL, withneutrophilicpredominance).Microscopy(a Gram stain showing Gram-negative diplococci), culture andpolymerase chain reaction(PCR) for meningococcus will confirm the diagnosis.
Patients suspected of raisedintracranialpressure or with afocalneurologicaldeficit may undergoCTscanning.
什么is the treatment of meningococcal disease?
Early recognition of meningococcal infection is critical as meningococcemia spreads so quickly that within hours of symptoms appearing, a patient may rapidly die. Patients may initially just have a rash and not be particularly unwell. Meningococcemia can kill more rapidly than any other infectious disease. Patients with either meningococcemia or meningococcal meningitis must be hospitalised and treated with antibiotics and supportive care immediately. Many patients are admitted to an intensive care unit.
Penicillinis the drug of choice. Some strains ofNeisseria meningitidisare resistant to penicillin have been isolated; in these cases, third-generation cephalosporins are a suitable alternative. Very sick patients are often treated with both penicillin and cephalosporins prior to obtaining the laboratory results.
Other treatments may include:
- intravenous fluids to treat shock and prevent organ damage
- 去甲肾上腺素等药物(去甲肾上腺素)for patients with very low blood pressure
- blood products such asplateletsand fresh frozenplasma
- oxygen and ventilation by a machine to assist with breathing
Patients who survive very severe cases of meningococcemia may have suffered severe necrosis (cell death) of skin and underlying tissue. Skin grafts and amputation may be necessary.
什么are the complications from meningococcal disease?
Complications from meningococcal disease may occur at the time of the acute disease or during the recovery period. Some complications are so severe that they may reduce the chances of survival.
- Massivehaemorrhageof the adrenalglands
- 传播intravascularcoagulopathy(DIC), which prevents blood clotting
- Arthritis
- Heart problems, egpericarditis(inflammationof the sack surrounding the heart)
- Neurological problems, eg deafness orperipheralneuropathy(damage to thenervesin feet and hands)
- Permanentmusculoskeletalproblems
- Amputation
How to prevent meningococcal disease
There are two ways to prevent meningococcal disease. One is by immunisation with vaccines (immunoprophylaxis) and the other is giving antibiotic therapy to close contacts of patients with meningococcal disease (antimicrobialchemoprophylaxis).
| Antimicrobial chemoprophylaxis | Immunoprophylaxis |
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