Meningitis can be a catastrophic illness with devastating consequences, often including death and it can occur at any age from infants to seniors. Viruses and bacteria are responsible for most cases of meningitis, but less common infectious agents such as fungi can also play a role. Meningitis occurs when these infectious agents gain access to the cerebrospinal fluid surrounding the brain and spinal cord. Viral meningitis, sometimes called aseptic meningitis, can present with symptoms similar to bacterial meningitis. While more common, it is generally less serious than bacterial meningitis and patients usually get better without specific treatment. Most cases of viral meningitis occur in children under the age of five. Recently, West Nile Virus has been identified as an important cause of viral meningitis. The common factor in all forms of meningitis is inflammation and swelling of the membranes covering the brain and spinal cord.
Incidence:
For the purposes of this discussion we will focus on bacterial meningitis and the three bacteria mainly responsible for this more serious form of the disease, Streptococcus pneumoniae, Hemophilus influenzae type b and Neisseria meningitidis. These are the most common causes of bacterial meningitis beyond the neonatal period. A vaccine is now available for each of these three bacteria, and their widespread use has significantly decreased the incidence of these devastating infections. Meningitis cause by Hemophilus influenzae type b was the leading cause of meningitis in children before the 1990s when the Hib vaccine became available. In a testament to the importance of vaccines in preventive medicine, it is now the least common cause. Meningitis caused by Streptococcus pneumoniae is now the most common cause of bacterial meningitis in infants, children and adults in the United States, followed by Neisseria meningitidis.
Transmission:
The infectious agents causing meningitis are spread by respiratory contact, although they are less contagious than infections such as the common cold. Spread is usually by exchange of respiratory and throat secretions, such as by coughing and kissing. They are not spread by casual contact or by merely breathing the air where a patient has been. The bacteria causing meningitis generally reach the cerebrospinal fluid surrounding the brain and spinal cord by spread from the bloodstream.
Signs and Symptoms:
It is important to understand that the presenting symptoms and the most likely cause of meningitis can vary from one age group to another. Symptoms can appear quickly or after several days, but typically within 3 to 7 days after exposure. The symptoms of meningitis include fever and chills, nausea and vomiting, mental status changes, headache, stiff neck and sensitivity to light. In infants and young children, the symptoms can be much more subtle and a high index of suspicion is necessary. Because bacterial meningitis is a true medical emergency, anyone with these symptoms should seek immediate medical attention.
Diagnosis and Treatment:
The only way to confirm a diagnosis of meningitis is to do a lumbar puncture in order to examine the cerebrospinal fluid. When treated in time, each of the three most common bacteria causing meningitis can be treated with antibiotics. Because the disease can progress rapidly, physicians may begin intravenous antibiotics before the specific bacterial cause has been identified in the cerebrospinal fluid. Corticosteroids are often used to suppress inflammation and reduce swelling and pressure in the brain.
Neisseria Meningitidis:
It is no wonder that meningitis caused by the bacterium Neisseria meningitidis is one of the most dreaded infections by both health care providers and patients, alike. For that reason and because vaccination recommendations for this form of meningitis have recently been changed, it has been singled out for special attention in this article. Neisseria menigitidis occasionally presents as a fulminant infection with the rapid appearance of a rash consisting of red and purple spots mainly on the trunk and lower extremities. This overwhelming invasion of the bloodstream is referred to as meningococcemia and without immediate treatment with penicillin it can lead to loss of limbs, brain damage or death.
Meningococcal Vaccine Recommendations:
The CDC has recently made a change in the recommendations for the meningococcal vaccine to prevent infection with Neisseria meningitidis. While it still recommends the first dose be given at age 11, it now recommends an additional booster at age 16, because immunity wanes after five years. If the first dose was not given until age 13-15, then the booster should be given five years later. Conditions such as crowding and fatigue increase the likelihood of spreading respiratory infections and thus put young adults at a higher risk of acquiring meningococcal meningitis. At risk groups include military recruits and college freshman living in dorms. Travelers to areas where meningitis is endemic should consult with their personal physician concerning whether they should receive the meningitis vaccine.
For more information about the vaccine recommendations visit the following website: http://www.cdc.gov/meningitis/about/prevention.html