Meningitis can be very serious; as a matter of fact certain types of bacterial meningitis can be rapidly fatal without early treatment. It is one of the conditions considered to be a medical emergency that is related to infectious diseases.
Just a little basic anatomy before I continue. The brain and spinal cord have two protective coverings; the outer bone part consisting of the skull and spinal cord, and the inner three layers of membranes called the meninges.
Between and around the meninges are spaces, most importantly for our discussion is the subarachnoid space. The subarachnoid space is where cerebral spinal fluid (CSF) is found.
What is CSF? It is a fluid produced by the choroid plexus. It provides buoyancy and cushioning for the brain, it carries nutrients and cleanses waste from around the brain and spinal cord and helps the brain monitor the internal environment.
So what is meningitis? It is an infection within the subarachnoid space or throughout the meninges. Depending on the offending organism, meningitis is considered either septic (bacterial) or aseptic (viral).
How do microorganisms find their way to the central nervous system (CNS)? There are four routes of infection:
o Bloodborne
The organism in the bloodstream gets through the defense mechanism known as the blood-brain barrier. This is the most common way and not very well understood.
o From an infected site close to the CNS
Infections from the middle ear or sinuses that is close to or contiguous to the CNS.
o The result of surgery or trauma that may allow organisms into the CNS.
o Certain viruses like rabies or herpes simplex can travel along nerves to the brain.
Certain factors can make you more susceptible to meningitis. First is age. Due to a immature immune system, newborns are at greater risk. They usually pick up the organism from the colonized vaginal tract of the mother. Group B streptococci, E.coli and other gram negative rods and Listeria are the main causes of bacterial meningitis in the newborn.
Haemphilus influenza type B was once the number one cause of meningitis in children under 6. But since the introduction of the Hib vaccine, it has been extremely rare.
Neisseria meningitidis (meningococcal) are associated with young adults particularly in close environments like military barracks and college dormitories.
In adults, Streptococcus pneumonia (pneumococcal) and Listeria are important causes.
The respiratory tract is the primary portal of several of these organisms, hence factors that predispose someone to pneumonia also do so with meningitis; alcoholism, diabetes, splenectomy and immunosuppression.
In bacterial meningitis, the following symptoms are typical: high fever, severe headache, stiff neck, photophobia (sensitivity to light), skin rashes and seizures. Quick treatment is paramount to prevent serious complications and death.
Permanent deafness, neurological problems and hydrocephalus are all sequelae.
Chronic meningitis is a frequent problem in those people that are immunocompromised. Unlike acute bacterial meningitis, the chronic form may persist for long periods of time and are frequently the result of a slower growing organism like a fungus. Cryptococcus neoformans is a common cause of chronic meningitis.
Aseptic meningitis is associated with viral infections and is usually self-limiting. Some symptoms are like those in bacterial meningitis. Enteroviruses are by far the most common cause of aseptic meningitis.
Meningitis is diagnosed by staining and culturing CSF for the offending bacteria. In addition, chemical determination of glucose and protein concentration is useful indicators. The CSF is collected by means of a spinal tap.
Can meningitis be prevented? Some of the organisms that cause meningitis are spread via respiratory means. If you have close contact with someone with the disease, your risk is increased.
Handwashing is the key to preventing just about every contagious disease. Avoid certain types of foods if you are pregnant or immunocompromised because of the risk of Listeria.
Besides the previously mentioned vaccination for Haemophilus influenza type B, there is also a vaccine for pneumococcal meningitis as part of the immunization schedule for children less than two.
For adults older than 65, there is a pneumococcal vaccine that is recommended by the CDC.
For children ages 11-18, there is a vaccine for meningococcal meningitis. For your child to live in a college dormitory it is mandatory.
