What is Meningitis?

Meningitis is an infection of the meninges that are membranes that cover the brain and the spinal cord.

What are meninges?

Meninges are 3 connective tissue layers. They consist of the pia mater (closest to the central nervous system organs), the arachnoid and the dura mater (farthest from the brain and spinal cord).

They also include blood vessels and contain cerebrospinal fluid. These are the structures involved in meningitis, an inflammation of the meninges, which, if severe, may become encephalitis, an inflammation of the brain.

What is meningitis?

Meningitis is an infection of the meninges. The infection may be caused by bacteria or a virus, and it leads to the meninges becoming inflamed (swollen). This can cause serious damage to the nerves, brain and the spinal cord.

Symptoms of meningitis

Meningitis is commonly manifested by:

  • severe headache
  • vomiting
  • high fever
  • stiffness of the neck
  • sensitivity and eye pain on exposure to light
  • skin rash

Symptoms can differ in young children and babies.

Types of meningitis

Meningitis may be caused by bacteria and viruses and both types have some distinctive features. Meningococcal disease is the leading infectious cause of death in early childhood.

Bacterial meningitis

Bacterial meningitis is very serious and should be treated as a medical emergency. Left untreated this may lead to severe brain damage and infect the blood causing septicimeia. The most common infecting bacteria are Neisseria meningitidis bacteria.

In 2008 and 2009 in England and Wales saw 1,166 cases of meningitis due to this bacteria. However, with the successful vaccination against this bacteria also known as meningococcal bacteria the number of cases have declined. However, there is currently no vaccine to prevent meningococcal group B disease, which is the most common cause of bacterial meningitis in the UK.

Bacterial meningitis is most common in children who are under five years old and is often life threatening in infants under the age of one. It is also common among teenagers aged 15 to 19 years. Of all the cases around 15% are bacterial meningitis and 25% may manifest with septicaemia. In 60% of cases both may present together.

Viral meningitis

Viral meningitis is the more common but less severe type of meningitis. The number of cases are difficult to estimate since the symptoms are akin to a bout of flu. Viral meningitis is most common in children and is more widespread during the summer months.

Who gets meningitis?

Meningitis may affect people of all age groups. Infants and young children and the elderly are however more at risk. Viral meningitis is the most common cause of the condition. Every year around 2,500 cases of bacterial meningitis, and nearly 5,000 cases of viral meningitis, occur in the UK.

The people most at risk of getting meningitis include:

  • those who have CSF shunts placed in their brain for another pathology
  • those with defects in the dura
  • use of spinal procedures (eg spinal anaesthetics)
  • diabetics
  • those with bacterial endocarditis
  • alcoholism and liver cirrhosis
  • intravenous drug abuse
  • renal insufficiency
  • thalassemia
  • cystic fibrosis
  • hypoparathyroidism
  • splenectomy
  • sickle cell disease etc.

Crowding (e.g. schools, day care, military recruits and college students) raises risk of meningitis.

Prognosis or outcome

Viral meningitis usually gets better within a couple of weeks but bacterial meningitis needs aggressive treatment.

Bacterial meningitis needs to be treated with antibiotics, admission to the hospital and even admission to the intensive care units.

Meningococcal disease (the combination of meningitis and septicaemia) causes death in around one in 10 cases. In spite of cure some children may go on to develop complications, such as hearing loss, after having bacterial meningitis. Prevention is by complete vaccinations against the infection.

Meningitis Symptoms

Meningitis is the inflammation of the membranes that cover the brain and the spinal cord. Inflammation and infection of the meninges is often a life threatening medical condition as it can lead to brain infection and infection in the blood stream or septicaemia which can be fatal.

Meningitis may be caused by bacteria or by viruses. Viral meningitis usually is more common and runs a milder course while bacterial meningitis is a medical emergency.

By Mikael Häggström, via Wikimedia Commons

Bacterial meningitis symptoms

Bacterial meningitis is the more serious form of the condition. Symptoms begin suddenly and worsen rapidly. Meningitis commonly affects children and elderly but may affect all age groups.

Initial warning symptoms

Some of the initial warning symptoms include:

  • body ache and muscle pain in limbs and joints
  • shivering and cold hands and feet
  • bluish lips and pale skin
  • high fever

Early symptoms

Early symptoms of bacterial meningitis include:

  • feeling generally unwell
  • severe unrelenting headache
  • usually a very high fever
  • nausea and vomiting

Later symptoms

As the disease progresses the symptoms include:

  • drowsiness
  • confusion
  • seizures or fits
  • being unable to tolerate bright lights (photophobia) – this is less common in young children
  • stiff neck – less common in young children - the neck becomes stiff and it is difficult to bend the neck forwards
  • rapid breathing rate, rapid heart rate,  respiratory distress, altered mental state (confusion and delirium), poor urine output and extremely low blood pressure – this is a symptom of septicaemia and shock
  • blotchy red rash which is characteristic and does not fade or change colour when pressed with a glass slide. This is not always present - a rash is strongly suggestive of meningococcal septicaemia and should lead to urgent treatment and referral
  • Kernig's sign refers to pain and resistance on straightening the knees with the hips folded - this detects back stiffness and is characteristic of meningitis
  • Brudzinski's sign refers to pain and resistance on bending the head forward with the hips folded
  • focal paralysis and neurological deficits and abnormal pupils

Bacterial meningitis symptoms in young children

Young children and infants have some different symptoms that indicate meningitis. These include:

  • initial symptoms are those of irritability and refusal to be held or fed
  • becoming floppy and unresponsive
  • the baby may be stiff with jerky movements
  • unusual crying, shrill cry or unusual moaning
  • vomiting and refusing feeds
  • pale and blotchy skin
  • staring expression
  • very sleepy or drowsy with a reluctance to wake up
  • swelling of the soft part on the top of the head called the fontanelle

Viral meningitis symptoms

Viral meningitis is more common than bacterial meningitis. The illness appears much like flu and may have milder symptoms.

Common symptoms

Common symptoms of viral meningitis include:

  • headaches
  • fever
  • generally not feeling very well

More severe symptoms

In more severe cases of viral meningitis symptoms may be:

  • nausea and vomiting
  • neck stiffness
  • muscle or joint pain
  • diarrhoea
  • photophobia (sensitivity to light)

Meningitis Causes

Meningitis can be caused by bacteria or a virus. While bacterial meningitis is more dangerous, viral meningitis is more common and runs a milder course.

Bacterial meningitis causes

There are currently a number of bacteria that can lead to meningitis. Some of these include:

  • Neisseria meningitidis bacteria or Meningococcal bacteria - There are several different types of meningococcal bacteria called groups A, B, C, W135, Y and Z. At present there is a vaccine available that provides protection against group C meningococcal bacteria. Most cases of meningococcal meningitis, however, are caused by the group B bacteria.
  • Streptococcus pneumoniae bacteria or pneumococcal bacteria – These bacteria tend to affect babies and young children and the elderly because their immune system is weaker than other age groups.
  • Those who have a CSF shunt or have dural defects are likely to get meningitis caused by Staphylococcus
  • Patients having spinal procedures (eg spinal anaesthetia) are at a risk of meningitis caused by Pseudomonas spp.
  • Syphilis and Tuberculosis leading to meningitis as well as fungal meningitis are rare causes but are seen in HIV positive individuals and those with a suppressed immunity.

According to age group of the patient the most likely bacterial causes of meningitis include:

  • In new-borns - Pneumococcal bacteria or group B streptococci, Listeria monocytogenes, Escherichia coli
  • Infants and young children - H. influenzae type b, in children less than 4 years and being unvaccinated raises risk of meningitis due to Neisseria meningitidis, Streptococcus pneumonia
  • Older children and adults - S. pneumoniae, H. influenzae type b, N. meningitidis, Gram-negative bacilli, staphylococci, streptococci and L. monocytogenes.
  • Elderly and those with a suppressed immunity - S. pneumoniae, L. monocytogenes, tuberculosis (TB), Gram-negative organisms
  • After head injury or infection acquired after a hospital stay or procedure - includes infection with Klebsiella pneumoniae, E.coli, Pseudomonas aeruginosa, Staphylococcus aureus

Transmission of infection

The meningococcal bacteria that cause meningitis are usually spread through prolonged, close contact. Spread is possible by being in proximity of an infected person who passes on the bacteria by sneezing, coughing, kissing, sharing personal possessions like toothbrushes, cutlery, utensils etc.

Pneumococcal bacteria are also spread by close contact with an infected person and by coughing, sneezing etc. However, in most cases they only cause mild infection, such as a middle ear infection (otitis media). Those with a poor immune system may develop a more severe infection such as meningitis.

Viral meningitis causes

There are several viruses that may lead to viral meningitis. Vaccinations against many of these viruses have led to the decline in the incidence of several viral meningitis cases. For example measles, mumps and rubella (MMR) vaccine provides children with immunity against mumps, which was once a leading cause of viral meningitis in children.

Viruses that may cause meningitis include:

  • herpes simplex virus – this may lead to genital herpes and cold sores
  • enteroviruses – stomach flu virus - these have been responsible for causing polio in the past as well
  • Mumps virus
  • Echovirus
  • Coxsackie virus
  • Herpes zoster virus
  • Measles virus
  • Arbovirus
  • Influenza virus
  • HIV
  • West Nile virus

Transmission of the virus

Viral meningitis infection may be spread by close contact with the infected person and being exposed when the person sneezes and coughs.

Hand washing after they are contaminated with the virus – for example, after touching a surface or object that has the virus on it can prevent the spread.

Other causes of meningitis

Other causes of meningitis include:

  • Fungal meningitis – Caused by Cryptococcus, Histoplasma and Coccidioides species and seen in AIDS patients
  • Parasites causing meningitis – includes examples of eosinophilic meningitis caused by angiostrongyliasis
  • Other organisms like atypical tuberculosis, syphilis, Lyme disease, leptospirosis, listeriosis and brucellosis, Kawasaki's disease and Mollaret's meningitis
  • There may be no infection and only inflammation of the meninges leading to non-infective meningitis. This is caused by tumors, leukemia, lymphomas, drugs and chemicals given spinally or epidurally during anesthesia or other procedures, diseases like Sarcoidosis, Systemic lupus erythematosus and Behçet's disease etc.

Risk factors of meningitis

Risk factors of getting meningitis include:

  • Those living in close quarters like schools, colleges, military base, day care centers, student housings etc. are more at risk of getting meningococcal infections.
  • Those with CSF shunts placed in their brain for another pathology
  • those with defects in the dura
  • use of spinal procedures (eg spinal anaesthetics)
  • diabetics
  • those with bacterial endocarditis
  • alcoholism and liver cirrhosis
  • intravenous drug abuse
  • renal insufficiency
  • thalassemia
  • cystic fibrosis
  • hypoparathyroidism
  • splenectomy
  • sickle cell disease

Reviewed by April Cashin-Garbutt, BA Hons (Cantab)