Meningitis and Encephalitis :: Biology Medical Biomedical

Meningitis and Encephalitis Meningitis and encephalitis are two debilitating infections. They cause the inflammation of the meninges and the brain, respectively. Both of these infections are more common than the public believes them to be. Almost any bacteria or viruses can cause a form of this infection and any person of any age can contract this illness. In the United States many cases of meningitis and encephalitis are reported yearly. These two illnesses are often confused and considered by the general public to be one illness. But that is a myth. Meningitis and encephalitis are related, however, since encephalitis usually stems from the former. But meningitis causes inflammation of the meninges, or the lining of the brain, while encephalitis inflames the brain itself. Both of these inflammations have two forms: viral and bacterial. There are many different viruses that cause meningitis, such as mumps virus, echovirus, human entroviruses, HIV, arborviruses, west nile viruses, and many others. Mumps virus and Enteroviruses are the most common viruses that cause this infection. Viral meningitis tends to be more prevalent during the winter months. It is more likely to be found in adolescents or adults. Bacterial meningitis, like viral meningitis, is caused by many different organisms. Fifty percent of bacterial meningitis is caused by Streptococcus pneumoniae, and fifteen percent are caused by Neisseria meningitides. The rest is caused by different Streptococcus and Listeria bacteria. Bacterial meningitis is contagious through direct contact with the oral fluids of the effected person. Therefore, the significant other and household contacts are often a likely candidate to contract bacterial meningitis. Eighty percent of cases are in people under the age of 16 and the majority of that group is under 5-years old. Haemophilus influenzae are gram-negative rods and it is commonly found in the United States. Their cell has a polysaccharide capsule with outer-membrane proteins. It is also non-motile. This bacterium prefers a carbon dioxide rich atmosphere though some strains do not need it to survive. An unusual trait of this bacteria is that when it is cultured for a long time, it loses its capsule and then dies. H. influenzae causes most cases of meningitis that occur in children between the ages of 2 months to four years, although-the mortality rate is a low three percent. Neisseria meningitides is a gram-negative diplococci, or a cocci that travels in pairs. This species is one of two Neisseria that are harmful to people. It is a spherical bacterium with a polysaccharides capsules.