Central nervous systems infections

Also known as: meningitis, encephalitis, brain abscesses


Infections of the central nervous system affect the brain and spinal cord. It usually causes inflammation and swelling. 

What are central nervous system infections?

A central nervous system infection can occur when a virus or bacteria enters the brain. It may become a cause for concern when it gets to the brain. This can occur through the blood, the nerves, or a skull fracture.

These infections can be serious. Most cases can be treated quickly without long-term damage. When the central nervous system is infected, bacteria can multiply. Your body may then have a physical response through inflammation and swelling.

Meningitis develops when bacteria infects the meninges. This is the membrane that lines the brain and spinal cord. Bacterial meningitis is generally more serious than viral meningitis, but it’s usually not as infectious.

Encephalitis results in the swelling of the brain, and it’s usually caused by a viral infection. 

The herpes simplex virus is well known to cause cold sores and the human herpes viruses. This includes chickenpox and measles viruses. It can live in the nerves for years after infection. 

In some cases, the infection can travel to the brain and cause encephalitis. Other viruses that affect the central nervous system can be spread by insect bites. This includes the West Nile fever virus and the Japanese encephalitis virus.

A brain abscess can develop when a bacterial infection spreads into the brain.

What are the different types of meningitis?

The two different types of meningitis include those caused by bacteria or those caused by viruses.

Bacterial meningitis is caused by bacteria including: 

  • Neisseria meningitidis
  • Streptococcus pneumoniae 
  • Haemophilus influenzae type b 

Bacteria infect the meninges by spreading from the ears or through the hollow spaces within the bones between your eyes. 

Bacteria can also move from the nose or mouth into the bloodstream.This type of meningitis can also be spread by person-to-person contact through the exchange of bodily fluids, such as coughing or through sex.

The bacteria that can cause a meningitis infection are commonly found on the skin and nose. It is often harmless. Viral meningitis, also known as aseptic meningitis, is caused by enteroviruses. 

They can travel from the digestive tract or are sometimes spread by bites from insects, such as ticks or mosquitoes.

Other viruses that can cause aseptic meningitis include: 

  • Herpes simplex virus
  • Epstein–Barr virus
  • HIV
  • Varicella-zoster virus, which causes chicken pox and shingles
  • Mumps virus

Why does a central nervous system infection cause inflammation?

Central nervous system infections trigger an immune response. This involves white blood cells moving to the area of infection to attack the virus.

It can lead to excess fluid and plasma. This causes inflammation and swelling. It may become a concern when pressure rises within the skull. 

What are the main symptoms of meningitis?

The most common symptoms of meningitis include the following:

  • A headache, which can be very severe
  • A stiff neck that aches and feels tender
  • Fever
  • Nausea and vomiting
  • Feeling confused
  • Seizures
  • Light sensitivity

Different infections in the central nervous system have different symptoms. They may include:

  • Bacterial meningitis, that can cause a rash of red and purple spots on the chest, arms, and legs
  • Encephalitis, which can quickly develop into symptoms that resemble meningitis. This includes headaches, fever, nausea and vomiting
  • Brain abscesses, which can cause headaches, vomiting and drowsiness
  • Most symptoms are often caused by the body’s response to the virus

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