Meningococcal meningitis is caused by a bacterium called Neisseria meningitidis. A more common name of the germ is meningococcus. Meningococcal disease is a severe bacterial infection of the bloodstream or meninges (a thin lining covering the brain and spinal cord). Meningitis is an infection of the fluid of a person's spinal cord and the fluid that surrounds the brain. (2) Meningitis is spread through exchange of respiratory droplets or saliva with an infected person, including kissing, coughing, sneezing, and sharing drinking glasses, eating utensils, or cigarettes. Many people may carry this particular germ in their nose and throat without any signs of illness, while others may develop serious symptoms. (7)
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 being given to all children as part of their routine immunizations have reduced the occurrence of invasive disease due to H. influenzae. (1) Today, Streptococcus pneumoniae and Neisseria meningitidis are the leading causes of bacterial meningitis.
High fever, headache, and stiff neck are common symptoms of meningitis in anyone over the age of 2 years. These symptoms can develop over several hours, or they may take 1 to 2 days. (6) Other symptoms may include nausea, vomiting, discomfort looking into bright lights, confusion, and sleepiness. In newborns and small infants, the classic symptoms of fever, headache, and neck stiffness may be absent or difficult to detect, and the infant may only appear slow or inactive, or be irritable, have vomiting, or be feeding poorly. As the disease progresses, patients of any age may have seizures. (3)
Virulence factors that enable the meningococcus to initiate an infection include an antiphagocytic capsule that mediates resistance to complement-mediated lysis. Thirteen capsular serogroups, A, B, C, H, I, K, L, X, Y, Z, 29E, W135. (5) In particular, the proportion of meningococcal infections due to serogroup Y has been increasing nationally in the last several years. Serogroup Y is frequently associated with meningococcal pneumonia in both civilian and military populations. Antibiotics are used to treat people with both the (meningococcal) meningitis and meningococcemia. People who have come in close contact with the sick person any time during the two weeks before she/he became ill may also need to take antibiotics. Preventive treatments of all close contacts should be implemented up to two weeks after onset of the first case but preferably as soon as possible within the first 24 hours. Haemophilus vaccine (HiB vaccine) in children will help prevent one type of meningitis. Penicillin (benzypenicillin) is the drug of choice for the treatment of meningococcal disease. (1)
On arrival in hospital of a suspected case, blood for culture should be taken and penicillin should be given if this has not already been done. The dose (immediate dose for individuals over 10 years of age: 1200 mg, children aged 1 to 9 years: 600 mg, children below 1 year of age: 300 mg) should be given as soon as possible, ideally by intravenous injection. (1) However, resistance to penicillin has been increasingly reported during recent years and may account for treatment failures. Seven to 10 days of therapy with the adequate antibiotic are usually sufficient.
The new vaccine is very effective in preventing pneumococcalinfections. In a study of over 37,000 infants in California immunized with the new pnuemococcal conjugate vaccine at 2, 4, 6, and 12-15 months of age, the vaccine was 97% effective in preventing bacteremia (infection of the blood stream) and meningitis. The rate of severe pneumonia with positive chest x-ray was reduced by 33%. (4) In addition to the usual safety and effectiveness studies manufacturers are required to do, there have been a number of other studies carried out. There have been a number of co-coordinated studies in the UK carried out by the Public Health Laboratory Service in infants, toddlers, school children and students specifically designed to study the vaccines' performance in UK children. These studies have shown the vaccine to be safe and effective. (4)
References:
1. Department of Health. "The New Meningitis C Vaccine". 15th November
2. New York State Department of Health "Meningococcal Meningitis". March 2002.URL: http://www.health.state.ny.us/nysdoh/consumer/menin.htm accessed on 05/04/02.
3. Centers for Disease Control and Prevention. "Meningococcal Disease". February 25, 2002.URL: http://www.cdc.gov/travel/diseases/menin.htm accessed on 05/04/02.
4. Rice, Gillian Dr. "Meningitis" January 4,2002.URL: http://www.netdoctor.co.uk/diseases/facts/meningitis.htm accessed on 05/04/02.
5. Cowell Student Health Center. "Meningococcal Meningitis Vaccination". April 10, 2002.URL: http://healthcenter.ucdavis.edu/meningitis.html accessed on 05/04/02.
6. Johnson, Allen. "Meningitis Disease Facts". February 18,1999.URL: http://www.health.state.nd.us/ndhd/pubs/prevent/meningitis/meningitis_factsheet.htm accessed on 05/04/02.
7. Barnard Student Health Services. "Preventing Meningococcal Meningitis" 04/18/02.URL: http://www.barnard.edu/health/publications/meningh.htm accessed on 05/04/02.