In?ammation affecting the membranes of the BRAIN or SPINAL CORD, or usually both. Meningitis may be caused by BACTERIA, viruses (see VIRUS), fungi, malignant cells or blood (after SUBARACHNOID HAEMORRHAGE). The term is, however, usually restricted to in?ammation due to a bacterium or virus. Viral meningitis is normally a mild, self-limiting infection of a few days’ duration; it is the most common cause of meningitis but usually results in complete recovery and requires no speci?c treatment. Usually a less serious infection than the bacterial variety, it does, however, rarely cause associated ENCEPHALITIS, which is a potentially dangerous illness. A range of viruses can cause meningitis, including: ENTEROVIRUSES; those causing MUMPS, INFLUENZA and HERPES SIMPLEX; and HIV.
Bacterial meningitis is life-threatening: in the United Kingdom, 5–10 per cent of children who contract the disease may die. Most cases of acute bacterial meningitis in the UK are caused by two bacteria: Neisseria meningitidis (meningococcus), and Streptococcus pneumoniae (pneumococcus); other bacteria include Haemophilus in?uenzae (a common cause until virtually wiped out by immunisation), Escherichia coli, Mycobacterium tuberculosis (see TUBERCULOSIS), Treponema pallidum (see SYPHILIS) and Staphylococci spp. Of the bacterial infections, meningococcal group B is the type that causes a large number of cases in the UK, while group A is less common.
Bacterial meningitis may occur by spread from nearby infected foci such as the nasopharynx, middle ear, mastoid and sinuses (see EAR, DISEASES OF). Direct infection may be the result of penetrating injuries of the skull from accidents or gunshot wounds. Meningitis may also be a complication of neurosurgery despite careful aseptic precautions. Immuno-compromised patients – those with AIDS or on CYTOTOXIC drugs – are vulnerable to infections.
Spread to contacts may occur in schools and similar communities. Many people harbour the meningococcus without developing meningitis. In recent years small clusters of cases, mainly in schoolchildren and young people at college, have occurred in Britain.
Symptoms include malaise accompanied by fever, severe headache, PHOTOPHOBIA, vomiting, irritability, rigors, drowsiness and neurological disturbances. Neck sti?ness and a positive KERNIG’S SIGN appearing within a few hours of infection are key diagnostic signs. Meningococcal and pneumococcal meningitis may co-exist with SEPTICAEMIA, a much more serious condition in terms of death rate or organ damage and which constitutes a grave emergency demanding rapid treatment.
Diagnosis and treatment are urgent and, if bacterial meningitis is suspected, antibiotic treatment should be started even before laboratory con?rmation of the infection. Analysis of the CEREBROSPINAL FLUID (CSF) by means of a LUMBAR PUNCTURE is an essential step in diagnosis, except in patients for whom the test would be dangerous as they have signs of raised intracranial pressure. The CSF is clear or turbid in viral meningitis, turbid or viscous in tuberculous infection and turbulent or purulent when meningococci or staphylococci are the infective agents. Cell counts and biochemical make-up of the CSF are other diagnostic pointers. Serological tests are done to identify possible syphilitic infection, which is now rare in Britain.
Patients with suspected meningitis should be admitted to hospital quickly. General pracitioners are encouraged to give a dose of intramuscular penicillin before sending the child to hospital. Treatment in hospital is usually with a cephalosporin, such as ceftazidime or ceftriaxone. Once the sensitivity of the organism is known as a result of laboratory studies on CSF and blood, this may be changed to penicillin or, in the case of H. in?uenzae, to amoxicillin. Local infections such as SINUSITIS or middle-ear infection require treatment, and appropriate surgery for skull fractures or meningeal tears should be carried out as necessary. Tuberculous meningitis is treated for at least nine months with anti-tuberculous drugs (see TUBERCULOSIS). If bacterial meningitis causes CONVULSIONS, these can be controlled with diazepam (see TRANQUILLISERS; BENZODIAZEPINES) and ANALGESICS will be required for the severe headache.
Coexisting septicaemia may require full intensive care with close attention to intravenous ?uid and electrolyte balance, control of blood clotting and blood pressure.
Treatment of close contacts such as family, school friends, medical and nursing sta? is recommended if the patient has H. in?uenzae or N. meningitidis: RIFAMPICIN provides e?ective prophylaxis. Contacts of patients with pneumococcal infection do not need preventive treatment. Vaccines for meningococcal meningitis may be given to family members in small epidemics and to any contacts who are especially at risk such as infants, the elderly and immuno-compromised individuals.
The outlook for a patient with bacterial meningitis depends upon age – the young and old are vulnerable; speed of onset – sudden onset worsens the prognosis; and how quickly treatment is started – hence the urgency of diagnosis and admission to hospital. Recent research has shown that children who suffer meningitis in their ?rst year of life are ten times more likely to develop moderate or severe disability by the age of ?ve than contemporaries who have not been infected. (See British Medical Journal, 8 September 2001, page 523.)
Prevention One type of bacterial meningitis, that caused by Haemophilus, has been largely controlled by IMMUNISATION; meningococcal C vaccine has largely prevented this type of the disease in the UK. So far, no vaccine against group B has been developed, but research continues. Information on meningitis can be obtained from the Meningitis Trust and the Meningitis Research Foundation.... meningitis
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