The low down on meningitis

Posted on 31 July 2017

Meningitis is an illness caused by the inflammation of the meninges, the three membranes that line the brain and spinal cord. The condition occurs when fluid surrounding the meninges becomes infected.

The two most common forms of meningitis are viral and bacterial. There are several other forms of meningitis, including cryptococcal, which is caused by a fungal infection, and carcinomatous, which is cancer-related, but these types are rare.

Viral meningitis is by far more common than bacterial meningitis. Around 80% of viral meningitis is caused by enteroviruses, which are those viruses most commonly responsible for seasonal gastrointestinal and upper respiratory tract infections. However, they only occasionally cause meningitis.

Bacterial meningitis is usually the result of the spread of infections from the sinuses or middle ear, resulting from severe and untreated bacterial sinusitis. The sinuses are positioned close to the meninges lining the brain, and so in severe cases the infection in the sinuses can spread directly to the brain.

Dr Marcelle Smith, a neurologist at Mediclinic Sandton, explains that the incidence of bacterial meningitis in South Africa is estimated to be around five cases per 100 000 people. Viral meningitis statistics are not as well known, but globally the incidence is about 28 for every 100 000 people.

Symptoms

The most common symptoms of meningitis include a severe headache, nausea or vomiting, sensitivity of eyes to light, and pain and stiffness of the neck. In more severe cases, the person may be drowsy or even comatose.

In about 10% of cases, bacterial meningitis can be fatal, and around 20% of those who have suffered the illness live with long-term complications. Meningitis may involve the blood vessels or brain tissue, resulting in strokes, abscesses, nerve damage or hydrocephalus, which is the accumulation of cerebrospinal fluid. These complications are more likely to occur if treatment is delayed, and can produce permanent disability or even death.

‘It is important to seek medical advice if you experience any of the symptoms of meningitis. It is a serious and life-threatening condition which is usually treatable. Even a new onset severe headache in a person without history of headaches should always be taken seriously and investigated,’ warns Dr Smith.

Testing and treatment

A lumbar puncture (LP), also known as a spinal tap, is the only test that can reveal whether meningitis is present. It detects increased pressure in the central nervous system, as well as inflammation or bacteria in the spinal fluid.

‘Protein and glucose levels, as well as the presence of inflammatory cells and microscopic organisms, are used to determine what type of meningitis it is. Treatment involves hospital admission and treatment with antibiotics or antiviral medication. A brain scan may be performed to determine whether it is safe to perform the LP, or to look for complications,’ explains Dr Smith.

References:

  1. Fahey, BJ. Meningitis: Bacterial vs viral (www.nursing.advanceweb.com)
  2. Smit, J. Meningitis – the basics. Lancet Laboratories
  3. Brits,E. The epidemiology of meningitis among adults in a South African province with a high HIV prevalence
  4. Logan, S. Viral meningitis. BMJ: 21 Nov 2007
  5. Ogunbanjo, GA. Acute bacterial meningitis: A rational approach to management. SAFP 2000: 22
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