What is meningitis?

Meningitis is an inflammation of the meninges, the protective layers surrounding the brain and spinal cord. The most common cause is a viral infection; however, the most serious cause is a bacterial infection (bacterial meningitis). 

There are an estimated 1.2 million cases of bacterial meningitis in the world every year and about 180,000 deaths. [1]  Bacterial meningitis is estimated to cause 2% of all child deaths in the world. [2]  

Meningitis is an inflammation of the brain's protective layers, called the meninges. 

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Spinal cord

A bundle of nerve tissue that runs from the brain through the spinal column and connects the brain to the body, transmitting sensory and motor signals.

1. Control of epidemic meningococcal disease. WHO practical guidelines. 2nd edition. World Health Organisation. Accessed 27 April 2015 from

External link

2. Luksic I. Mulic R. Falconer R. et al. (2013) Estimating global and regional morbidity from acute bacterial meningitis in children: assessment of the evidence. Croatian Medical Journal 54: 510-518.

Causes

There are several possible causes of meningitis. The inflammation can be the result of infection with bacteria, viruses or fungi. It can also result from non-infectious causes such as inflammatory diseases.

Bacteria

Microscopic, single-celled organisms with DNA but no definite nucleus. Bacteria are the cause of many human diseases.

Fungi

An organism from the fungi kingdom, which is a separate group to plants or animals, and includes yeasts, moulds and mushrooms. Fungi feed on organic matter.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Viruses

A microscopic infectious agent that replicates itself only within cells of living hosts; a piece of nucleic acid (DNA or RNA) wrapped in a protein coat.

1. Control of epidemic meningococcal disease. WHO practical guidelines. 2nd edition. World Health Organisation. Accessed 27 April 2015 from

External link

2. Luksic I. Mulic R. Falconer R. et al. (2013) Estimating global and regional morbidity from acute bacterial meningitis in children: assessment of the evidence. Croatian Medical Journal 54: 510-518.

Types

Bacterial meningitis

Bacterial meningitis can be extremely serious and is treated as a medical emergency as it can be fatal, if not appropriately treated. Bacterial meningitis can be spread through contact with saliva and nasal droplets. It can be caught through close contact, such as sharing a room or household with an infected person.

About one in 10 people is a healthy carrier of the bacteria that cause meningitis. [3]  These people do not suffer any symptoms, but can transfer the bacteria to others.

Some of the most common bacterial species that cause meningitis include:

  • Streptococcus pneumoniae;
  • Neisseria meningitidis (also known as Meningococcus), and;
  • Streptococcus agalactiae / group B streptococcus.

Other bacterial species known to cause meningitis are

  • Haemophilus influenza type B;
  • Listeria monocytogenes, and;
  • Escherichia coli (E. coli).

Non-bacterial meningitis

Viral meningitis

Viral meningitis is more common and normally milder than bacterial meningitis, though it can be highly contagious. Most people recover from viral meningitis without any permanent damage. It is common in children and young adults.

Viruses that can cause meningitis include:

Viruses that cause diseases such as measlesmumps and the flu can also result in meningitis, as a complication of these diseases. However, infection with these viruses can be preventable by vaccination.

Fungal meningitis

Fungal meningitis is rare and not contagious. It can develop when a fungus gets into your bloodstream or central nervous system. Fungal meningitis can develop very slowly and generally occurs in people with a weak immune system.

Infection is often a result of inhalation of the fungal spores. These spores are normally found in the soil or in animal droppings, but are sprayed into the air when dust or droppings are disturbed, such as by being kicked or stepped on.

Parasitic meningitis

Rarely, meningitis is caused by infection with single-celled parasites, such as amoebas. This typically occurs when a person swims in water where the parasites are found and the contaminated water enters the nose. This rare condition is dangerous and often fatal.

Non-infectious meningitis

Inflammation of the meninges can also occur without any infection. Some causes of non-infectious meningitis include:

Allergic reaction

A problematic physiological response to an allergen that comes into contact with the body.

Bacteria

Microscopic, single-celled organisms with DNA but no definite nucleus. Bacteria are the cause of many human diseases.

Central nervous system

The part of the body's nervous system that includes the brain and the spinal cord.

Fungus

An organism from the fungi kingdom, which is a separate group to plants or animals, and includes yeasts, moulds and mushrooms. Fungi feed on organic matter.

Herpes simplex virus

A highly contagious virus that gives rise to cold sores, genital infections, skin and eye lesions, and nervous system disorders. They commonly cause persisent infections.

Immune system

The organs and cells involved in protecting the body against infection.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Parasites

An organism that lives off another organism.

Vaccination

The practice of administering a vaccine, a solution containing a microorganism (that causes a specific disease) in a dead or weakened state, or parts of it, for the purpose of inducing immunity in a person to that microorganism.

Viruses

A microscopic infectious agent that replicates itself only within cells of living hosts; a piece of nucleic acid (DNA or RNA) wrapped in a protein coat.

Enteroviruses

A group of viruses that multiply in the gut and attack the central nervous system causing conditions such as polio, hepatitis A, meningitis, and hand, foot and mouth disease.

Arboviruses

Any group of viruses that is transmitted from insects to humans, causing diseases such as yellow fever.

3. Meningococcal meningitis. World Health Organisation. Accessed 20 April 2015 from

External link

Risk factors

Weak immune system

Factors that can affect the immune system include:

  • Age (young children and elderly people);
  • Disease (for example, HIV/AIDS), and;
  • Medical procedures, such as chemotherapy or organ transplant.

Environmental factors

People in an environment where meningitis infections are more likely to occur include:

  • Young adults forced to sleep in crowded conditions, such as university dorms or army barracks, and;
  • People living in, or travelling to, the 'meningitis belt', a region of sub-Saharan Africa where bacterial meningitis is common. Once every 8-12 years, the region experiences widespread outbreaks that may cause tens of thousands of deaths.

Chemotherapy

A medication-based treatment, usually used in the treatment of cancers. There are numerous, different types of chemotherapy drugs that can be prescribed by a specialist. These can commonly be used alongside other cancer treatments such as surgery and radiotherapy.

Immune system

The organs and cells involved in protecting the body against infection.

Infections

Entry into the body of microorganisms that can reproduce and cause disease.

3. Meningococcal meningitis. World Health Organisation. Accessed 20 April 2015 from

External link

Signs and symptoms

The signs and symptoms of meningitis can closely resemble those of the flu. They can appear quickly, sometimes hours after infection, or over a few days. It is not possible for a person to diagnose themselves or family members with meningitis. It is therefore very important to seek professional medical help if you suspect meningitis.

Symptoms in adults

The 'classic' symptoms of meningitis in adults include:

  • Fever;
  • Severe headache;
  • Stiff neck, and;
  • Altered mental state - confusion or trouble concentrating, unintelligible speech.

At least two of these symptoms appear in nearly all people with bacterial meningitis. Additional symptoms of meningitis may include:

  • Chills;
  • Head and neck arching backwards;
  • Joint pain, muscle pain;
  • Vomiting, nausea;
  • Sleepiness or difficulty waking up;
  • Skin rash - reddish-purple spots the size of pinpricks, or larger dark purple bruise-like spots;
  • Sensitivity to light;
  • Seizures;
  • Rapid breathing, and;
  • Lack of appetite.

Symptoms in infants

In infants, the symptoms of meningitis might appear slightly different. They include:

  • High fever;
  • Sleepiness;
  • Irritability, constant crying, moaning or grunting;
  • Inactivity;
  • Lack of appetite, no interest in feeding;
  • Vomiting, nausea;
  • Stiffness in the body and neck, and;
  • A swelling in the soft spot on top of the baby's head (fontanelle).

fever, sleepiness, vomiting and nausea, stiffness in the body and neck, Irritability, constant crying, moaning or grunting, inactivity, lack of appetite and a swelling on the fontanelle, are symptoms of meningitis in infants.Symptoms of meningitis in infants. 

Fever

An increase in body temperature above the normal temperature range. Fever is often caused by the body's immune reaction to infection.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Seizures

A sudden, involuntary contraction of muscle groups caused by abnormal electrical activity in the brain.

3. Meningococcal meningitis. World Health Organisation. Accessed 20 April 2015 from

External link

Methods for diagnosis

Meningitis can be difficult to diagnose in the early stages, because the symptoms can be similar to the flu. If your doctor suspects that you have meningitis, they may perform one or more of the following tests:

  • Physical examination to check for signs of infection;
  • Lumbar puncture (spinal tap), to take a sample of fluid from around your spinal cord;
  • Blood sample to check for infection, and;
  • Computerised tomography (CT) scan or magnetic resonance imaging (MRI) scan of your head to check for other causes of symptoms. This may be performed in some people before the lumbar puncture to exclude conditions that may make lumbar puncture dangerous. In most cases of suspected or likely meningitis, the lumbar puncture is performed first and is the most important test.

Computerised tomography

A scan that uses X-rays to create a 3D image of the body. This can detect abnormalities more effectively than a simple X-ray can.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Magnetic resonance imaging

A type of imaging that uses a magnetic field and low-energy radio waves, instead of X-rays, to obtain images of organs.

Spinal cord

A bundle of nerve tissue that runs from the brain through the spinal column and connects the brain to the body, transmitting sensory and motor signals.

Lumbar puncture

A procedure that uses a needle to collect a sample of cerebrospinal fluid, which is the clear fluid surrounding the brain and spine, from the lower back (lumbar region) for analysis. It can also be performed to remove any excess fluid or to deliver medications.

3. Meningococcal meningitis. World Health Organisation. Accessed 20 April 2015 from

External link

Types of treatment

The type of treatment depends on the cause of the meningitis.

Bacterial meningitis

Bacterial meningitis is promptly treated in a hospital with high doses of antibiotics, given intravenously. 

Non-bacterial meningitis treatment

Treatment of non-bacterial meningitis is usually managing the symptoms, providing plenty of fluids and making sure that the inflammation does not cause pressure on the brain. Meanwhile, the person's immune system takes care of the infecting virus.

In some cases of viral meningitis where the immune system is weak, specific antiviral therapy may be recommended.

Fungal meningitis is normally treated with antifungal medication, such as amphotericin B or fluconazole. Parasitic meningitis is treated with antiparasitic medications.

Immune system

The organs and cells involved in protecting the body against infection.

Virus

A microscopic infectious agent that replicates itself only within cells of living hosts; a piece of nucleic acid (DNA or RNA) wrapped in a protein coat.

3. Meningococcal meningitis. World Health Organisation. Accessed 20 April 2015 from

External link

Potential complications

Bacterial meningitis is still a dangerous condition today, and can lead to serious complications and death. Untreated bacterial meningitis is usually fatal. Even with treatment, there is still a real chance of death or serious disability.

After-effects of the infection are also more pronounced in bacterial meningitis than in other kinds.

Viral meningitis is usually less severe and will normally clear up on its own in 2-4 weeks, but complications can still occur.

Meningitis complications result from the damage that the inflammation causes to various areas of the brain. Complications can include:

After-effects

Some people recovering from meningitis may suffer from after-effects of the inflammation. These problems can linger for some time after the episode has passed, but usually get better eventually. They can include:

  • Hearing difficulties;
  • Ringing in the ears (tinnitus);
  • Recurring headaches;
  • Vision problems, and;
  • Impaired thinking and learning.

Blood infections

Bacterial meningitis can lead to contamination of the bloodstream with the infecting bacteria (septicaemia or bacteraemia), a dangerous complication of meningitis. Blood infections can lead to arthritis, gangrene, kidney failure, septic shock and death.

Bacteria

Microscopic, single-celled organisms with DNA but no definite nucleus. Bacteria are the cause of many human diseases.

Gangrene

The death of a mass of body tissue, usually resulting from obstructed blood supply or bacterial infection.

Hydrocephalus

The abnormal accumulation of fluid in the brain.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Paralysis

An inability to move or feel; a loss of muscle function or sensation.

Seizures

A sudden, involuntary contraction of muscle groups caused by abnormal electrical activity in the brain.

Septic shock

A life-threatening condition in which the blood pressure falls to dangerously low levels due to a widespread infection.

3. Meningococcal meningitis. World Health Organisation. Accessed 20 April 2015 from

External link

Prevention

Preventing infections

There is no guarantee against meningitis; complete prevention is not yet available. You can lower the risk of bacterial meningitis by avoiding close contact (sharing a room, household, dormitory, kissing or sharing food and cutlery) with an infected person.

Close contacts (family, household members) of people that have been diagnosed with bacterial meningitis may receive antibiotic treatment to prevent infection and development of disease.

Vaccination

Vaccines are available against the most dangerous types of bacteria that cause bacterial meningitis, as well as against some of the viruses that cause meningitis. The vaccines do not cover all possible infectious causes of meningitis. In many countries, these vaccines are offered as part of the regular childhood vaccination schedule. Vaccination is also often recommended for:

  • Unvaccinated older children about to enter secondary school;
  • Young adults who are expected to enter situations where they will be sleeping in crowded conditions, such as university dorms or army barracks, and;
  • People living in or travelling to at-risk areas. 

Bacteria

Microscopic, single-celled organisms with DNA but no definite nucleus. Bacteria are the cause of many human diseases.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Vaccination

The practice of administering a vaccine, a solution containing a microorganism (that causes a specific disease) in a dead or weakened state, or parts of it, for the purpose of inducing immunity in a person to that microorganism.

Viruses

A microscopic infectious agent that replicates itself only within cells of living hosts; a piece of nucleic acid (DNA or RNA) wrapped in a protein coat.

3. Meningococcal meningitis. World Health Organisation. Accessed 20 April 2015 from

External link