What is Meningitis?

Meningitis is a disease, normally infectious, that causes inflammation in the meninges. This causes symptoms like fever, headaches and loss of attention
What is Meningitis?

Last update: 03 January, 2019

What is meningitis?

Meningitis is the inflammation of the membranes that coat the central nervous system, or meninges. Since it causes abnormal inflammation in the body, this inflammation is a disease. The good news is that this disease is currently not very common.

It is normally caused by infectious agents. The most common is viral meningitis. However, the bacterial case is more serious.

Meningitis can end up damaging the brain. Unfortunately, it can even lead to death. That’s why it’s essential that you diagnose it and start to treat it as early as possible.

what is meningitis

What are the meninges?

Imagine for a minute that your brain is a type of fruit. This fruit contains a nut and a liquid inside of it. The liquid travels through various points of the nut in order to keep it in good condition.

Now, imagine that the skin of the fruit is the skull. Then, what’s under the skin, the nut, is our brain: soft, smooth, and fragile. Underneath the skin- the external layer-of the fruit – there are three other layers through which the liquid circulates to preserve the fruit.

These three layers below the skull are the meninges. They’re three membranes that coat and protect the brain and the spinal cord, or the central nervous system.

Remember that the brain and the spinal cord are the most protected organs in the body. The meninges not only absorb blows, but also act as “filters” to keep dangerous microorganisms from entering the central nervous system. Meanwhile, a cerebrospinal liquid circulates through the meninges. This liquid also has protective and immune functions.

Distribution of meningitis

Meningitis has become a frequent epidemic on the continent of Africa, especially in sub-Saharan Africa during the dry season. The epidemics in this zone last between two and three years, and are interrupted by periods of rain. Unfortunately, the lack of medical attention causes high mortality rates in the population. The most grave meningitis epidemic that took place in this area was in the year 1996, causing more than twenty-five thousand deaths.

In western countries, bacterial meningitis affects three in every one-hundred thousand people. Meanwhile, the the virus affects ten in every one-hundred thousand.

Risk factors

  • Dry seasons
  • Children
  • Contagious infections
  • Immunosuppression
  • Intoxication

Causes of meningitis

Meningitis is normally a consequence of another infection – usually a virus. However, there are also non-infectious cases of meningitis.


  • Enterovirus
  • Simple herpes virus
  • HIV
  • West nile virus (transmitted through mosquitos).


According to the age of the individual, there are different risks of infection that come from different microorganisms.

  • Newborns under three months:
    • Group B Streptococcus
    • E Coli
  • Children over three months:
    • Neisseria meningitidis
    • Streptococcus pneumoniae
    • Haemophilus influenzae
  • Adults:
    • Neisseria meingiditis
    • Streptococcus pneumoniae
    • Listeria monocytogenes

How does the disease show up?

The microorganisms get into the meninges through the blood stream, either directly or by contiguity.

The bacteria that are normally in the nose, mouth and pharynx that normally don’t cause harm pass through the blood stream. From there, they cross the blood-brain barrier in the zones where it is most vulnerable.

Then, the bacteria reaches the cerebrospinal fluid of the subarachnoid space and causes an infection in the meninges. 

The other means of transmission are direct, like fractures in the skull, surgical interventions, etc. or the transmission by contiguity from the zones like the para-nasal sinuses.


  • Fever, especially in kids and newborns
  • Shaking and chills
  • Nausea and vomiting
  • Photophobia
  • Stiff neck
  • Convulsions
  • Headaches
  • Decreased levels of consciousness

The diseases comes about abruptly, with fever, headaches, nausea and vomiting. However, in children it can be less specific symptoms like irritability and drowsiness. 

Cerebral damage

Cerebral edema is an injury that often comes from inflammation. This provokes an increase in the intracranial pressure, which makes it hard for blood to reach the brain.

Then, the brain does not get enough oxygen and the brain cells start to die. In some cases, especially if the meningitis is not treated, the brain injury can be deadly. 

Diagnosing Meningitis

The suspicion of meningitis is always clinical. However, getting an exact diagnosis occurs with a lumbar puncture. 

Remember that a lumbar puncture is a procedure that consists of the extraction of the cerebrospinal liquid through a needle that doctors insert into the vertebrae.

Diagnose Meningitis

Types of meningitis

Meningitis can be viral or bacterial according to its etiological agent.

  • Viral meningitis has a mild prognostic and does not require treatment.
  • However, bacterial meningitis is very serious and requires hospitalization for treatment. This case has a high risk of death, even with treatment.

Also, you can divide the disease up according to its evolutionary course- acute, subacute and chronic. however, this criteria is not commonly used.


The patient should be given antivirals and antibiotics as soon as possible. 

To reduce inflammation and cerebral edema, doctors administer corticosteroids like dexamethasone. This reduces the risk of cerebral injury.

In addition, there are also general methods to help any acute infections, like drinking a lot of liquids, controlling your fever, etc.

Treatment at the right time greatly reduces the presence of other problems in the long run, as well as the risk of death.

Possible consequences

  • Deafness
  • Epilepsy
  • Cognitive deficit
  • Hydrocephalus
  • Death

Newborns and adults have between a twenty and thirty percent chance of the illness being deadly. The risk decreases to two percent in older children.


Currently, a vaccine is being worked on for preventing meningitis in children. The vaccine is optional and can be administered after the child’s first two months of life.

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