What is Meningitis? What Causes Meningitis?

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Main Category: Infectious Diseases / Bacteria / Viruses
Also Included In: Neurology / Neuroscience;  Pediatrics / Children's Health
Article Date: 19 May 2009 - 21:00 PST

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The word "meningitis" comes from the Modern Latin word meninga and the Greek word Menix meaning "membrane". The suffix "itis" comes from the Greek word itis meaning "pertaining to". In medical English, the suffix "-itis means" "inflammation of". The membranes that surround the brain and the spinal cord are collectively known as the meninges - meningitis means inflammation of the meninges. According to According to According to Medilexicon's medical dictionary, meningitis is "Inflammation of the membranes of the brain or spinal cord".

A recent study found that rates of meningitis have decreased in Canadian provinces introducing routine immunization of children and adolescents against one specific strain of meningococcal bacteria.

What causes meningitis?

Meningitis is generally caused by infection of viruses, bacteria, fungi, parasites, and certain organisms. Anatomical defects or weak immune systems may be linked to recurrent bacterial meningitis. In the majority of cases the cause is a virus. However, some non-infectious causes of meningitis also exist.

Bacteria mimic human cells to get in and stay in

A study carried out by researchers at the University of Oxford and Imperial College London, England, revealed the way in which bacteria that cause bacterial meningitis mimic human cells is to evade the body's innate immune system.

• Viral meningitis
  
  Although viral meningitis is the most common, it is rarely a serious infection. It can be caused by a number of different viruses, such as mosquito-borne viruses. There is no specific treatment for this type of meningitis. In the vast majority of cases the illness resolves itself within a week without any complications.


• Bacterial Meningitis
  
  Bacterial meningitis is generally a serious infection. It is caused by three types of bacteria: Haemophilus influenzae type b, Neisseria meningitidis, and Streptococcus pneumoniae bacteria. Meningitis caused by Neisseria meningitides is known as meningococcal meningitis, while meningitis caused by Streptococcus pneumoniae is known as pneumococcal meningitis. People become infected when they are in close contact with the discharges from the nose or throat of a person who is infected.
  
  Twenty years ago Hib was the main cause of bacterial meningitis - it is not any more thanks to new vaccines which are routinely administered to children.
  
  The doctor needs to know what type of meningitis has infected the patient. Certain antibiotics can stop some types from infecting others.


• Bacterial meningitis in newborns and premature babies
  
  A type of streptococci, called group B streptococci commonly inhabits the vagina and is a common cause of meningitis among premature babies and newborns during the first week of life. Escherichia coli, which inhabit the digestive tract, may also cause meningitis among newborns. Meningitis that occurs during epidemics can affect newborns - Listeria monocytogenes being the most common.


• Bacterial meningitis in children under 5
  
  Children under five years of age in countries that do not offer the vaccine are generally infected by Haemophilus influenzae type B.


• Bacterial meningitis in older children
  
  Older children generally have meningitis caused by Neisseria meningitides (meningococcus), and Streptococcus pneumoniae (serotypes 6, 9, 14, 18 and 23) .


• Bacterial meningitis in adults
  
  About 80% of all adult meningitis are caused by N. meningitidis and S. pneumoniae. People over 50 years of age have an increased risk of meningitis caused by L. monocytogenes.


• Bacterial meningitis and people with skull damage implanted devices
  
  People who received a recent trauma to the skull are at increased risk of bacteria in their nasal cavity entering the meningeal space. Patients with a cerebral shunt or related device also run a higher risk of infection with staphylococci and pseudomonas through those devices.


• Bacterial meningitis and weak immune systems
  
  People with weak immune systems are also at higher risk of infection with staphylococci and pseudomonas.


• Bacterial meningitis and ear infections and procedures
  
  Rarely, otitis media, mastoiditis, or some infection to the head or neck area may lead to meningitis. People who have received a cochlear implant run a higher risk of developing pneumococcal meningitis. (Cochlear Implantation Increases Meningitis Risk). Another study found that Children who are stricken with severe hearing loss are five times more likely to contract meningitis.
  
  In countries where tuberculous meningitis is common, there is a higher incidence of meningitis caused by Mycobacterium tuberculosis.


• Anatomical defects or disorders of the immune system
  
  Either congenital or acquired anatomical defects may be linked to recurrent bacterial meningitis. An anatomical defect might allow a way to penetrate into the nervous system from the external environment. The most common anatomical defect which leads to meningitis is skull fracture, especially when the fracture occurs at the base of the brain, or extends towards the sinuses and petrous pyramids.
  
  59% of recurrent meningitis cases are due to anatomical defects, while 36% are due to weakened immune systems.

What are the symptoms of meningitis?

As meningitis and septicemia tend to show similar symptoms and incidences of both tend to rise and fall at the same time in geographical areas, this section refers to both meningitis and septicemia.

Meningitis is not always easy to recognize. In many cases meningitis may be progressing with no symptoms at all. In its early stages, symptoms might be similar to those of flu. However, people with meningitis and septicemia can become seriously ill within hours, so it is important to know the signs and symptoms. Early symptoms of meningitis broadly include:

• Vomiting
• Nausea
• Muscle pain
• High temperature (fever)
• Headache
• Cold hands and feet
• A rash that does not fade under pressure. This rash might start as a few small spots in any part of the body - it may spread rapidly and look like fresh bruises. This happens because blood has leaked into tissue under the skin. The rash or spots may initially fade, and then come back.

In babies, you should look out for at least one of the following symptoms:

• a high-pitched, moaning cry
• a bulging fontenelle
• being difficult to wake
• floppy and listless or stiff with jerky movements
• refusing feeds
• rapid/ unusual/ difficult breathing
• pale or blotchy skin
• red or purple spots that do not fade under pressure

In older children, you should look out for:

• a stiff neck
• severe pains and aches in your back and joints
• sleepiness or confusion
• a very bad headache (alone, not a reason to seek medical help)
• a dislike of bright lights
• very cold hands and feet
• shivering
• rapid breathing
• red or purple spots that do not fade under pressure

What is the glass test?

• Press the side of a drinking glass firmly against the rash.
• If the rash fades and loses color under pressure it is not a meningitis rash.
• If it does not change color you should contact a doctor immediately.

What is the treatment for meningitis?

In an interesting study, UK researchers looked at whether children with suspected meningitis should be given antibiotics before their transfer to hospital.

Meningitis treatment will generally depend on four main factors:

• The age of the patient
• The severity of the infection
• What organism is causing it?
• Are other medical conditions present?

Viral meningitis will resolve itself fairly quickly and does not usually need any medical treatment. If symptoms continue after two weeks the person should see his/her doctor.

The treatment for severe meningitis, which is nearly always bacterial (but can be viral), may require hospitalization, and includes:

• Antibiotics - usually administered intravenously by injection, or through an IV.


• Corticosteroids - if the patient's meningitis is causing pressure in the brain, corticosteroids, such as dexamethasone, may be administered to adults and children.


• Acetaminophen (paracetamol) - effective in bringing the patient's temperature down. Other methods for reducing the patient's fever may include a cool sponge bath, cooling pads, plenty of fluids, and good room ventilation.


• Anti-convulsants - if the patient has seizures (fits), he/she will be given an anti-convulsant, such as phenobarbital or dilantin.


• Oxygen therapy - if the patient has breathing difficulties oxygen therapy may be given. This may involve a face mask, a nasal cannula, a hood, or a tent. In more severe cases a tube may be inserted into the trachea via the mouth.


• Fluid control - dehydration is common for patients with meningitis. If a meningitis patient is dehydrated he/she may develop serious problems. It is crucial that he/she is receiving adequate amounts of fluids. If the patient is vomiting, or cannot drink, liquids may be given through an IV.


• Blood tests - measuring the patient's blood sugar and sodium is important, as well as other vital body chemicals.


• Sedatives - these are given if the patient is irritable or restless.

If the meningitis is severe the patient may be placed in an ICU (intensive care unit).

Scientists at the University of Nottingham have finally discovered how the deadly meningococcal bacteria is able to break through the body's natural defence mechanism and attack the brain. This could lead to better treatment and vaccines for meningitis. (click here to read about it).

Written by Christian Nordqvist

Original article date: 08 Jun 2004
Article updated: 19 May 2009

Copyright: Medical News Today
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