Types of Meningitis

• Meningococcal Meningitis
• Acute Pyogenic Meningitis
• Tuberculous Meningitis
• Viral Meningitis
• Benign Lymphocytic Meningitis

Meningococcal Meningitis

The meningococcus is spread by droplet infection and enters the body through the naso-pharynx, and is carried in the blood stream to the brain and meninges, where it enters the cerebro-spinal fluid. This type of meningitis occurs sporadically, and in epidemics in children and young adults living in crowded conditions such as schools, colleges, universities, and barracks. Spread of infection may be due to symptomless carriers of the organism, and this can be up to 5% to 10% of the population.

In 1999 the UK introduced routine immunisation against type C meningococcal infection for infants, running a catch-up programme for older children and teenagers. New students at University or College have a higher risk of developing meningitis, and have a higher mortality rate than babies. It is therefore important for them to be vaccinated if they have not already received it.

The disease must be distinguished from other causes of meningitis and meningism, e.g, sub-arachnoid hemorrhage, and acute infectious diseases in children.

Acute Pyogenic Meningitis

Infection by staphylococci (G00.3), pneumococci (G00.1), Haemophilus Influenzae (G00.0), or Streptococci (G00.2) sometimes occurs primarily in the meninges, but is more commonly secondary to infection in the heart, lungs, bones, and elsewhere.

Tuberculous Meningitis

The usual source of infection is a site elsewhere in the body, which has spread to the meninges via the blood stream. The condition occurs most commonly shortly after a primary infection in childhood, but people of any age may be affected.

Viral Meningitis

Viral infections of the central nervous system are often associated with meningitis, and there are several well recognised clinical types. Meningitis may occur as a complication of viral infections affecting other organs, e.g., mumps, glandular fever, psittacosis, herpes zoster, and infectve hepatitis.

In the absence of evidence of viral disease of other organs the various types of viral meningitis can only be differentiated by the virologist. Viral meningitis is the most common type now found in the UK.

Benign Lymphocytic Meningitis

Occurs sporadically or in small epidemics, and believed to be endemic in house mice. The condition commonly occurs in children and young adults.