Meningitis is an infection of the fluid of a person's spinal cord and the fluid that surrounds the brain. People sometimes refer to it as spinal meningitis. Meningitis is usually caused by a viral or bacterial infection. Knowing whether meningitis is caused by a virus or bacterium is important because the severity of illness and the treatment are different. Viral meningitis is generally less severe and resolves without specific treatment, while bacterial meningitis can be quite severe and may result in brain damage, hearing loss, or learning disability. For bacterial meningitis, it is also important to know which type of bacteria is causing the meningitis because antibiotics can prevent some types from spreading and infecting other people. Before the 1990s, Haemophilus influenzae type b (Hib) was the leading cause of bacterial meningitis, but new vaccines are being given to all children as part of their routine immunizations. This has reduced the occurrence of invasive disease due to H.
influenzae. Today, Streptococcus pneumoniae and Neisseria meningitidis are the leading causes of bacterial meningitis. The bacteria that cause bacterial meningitis live in the back of the nose and throat area and are carried at any given time by between 10% and 25% of the population. It causes meningitis when it gets into the bloodstream and travels to the meninges. What triggers this movement in a small number of unfortunate people remains the subject of research. With viral meningitis, the viruses responsible can be picked up through poor hygiene or polluted water.
In blood, infection is fought off by white blood cells. In the spinal fluid, there are no white blood cells...and there is nothing there to fight off infection. Once the infection starts, it can spread very quickly throughout the body. Meningitis can cause a great deal of brain damage in...