Meningococcal Meningitis

Infection with N. meningitidis is a Serious but Preventable Disease

Nov 6, 2008 Stephen Allen Christensen

Meningitis is an infection of the brain and the membranes around it. A variety of organisms can be the cause, but meningococcus is one of the most common--and frightening

Meningitis.

The word strikes terror into the heart of a parent. And when the phrase “meningococcal meningitis” is uttered, entire communities grow fearful.

Neisseria meningitidis (meningococcus) is the most common cause of bacterial meningitis in children and young adults in the United States and the second most common cause of community-acquired meningitis in adults. Due to the aggressive nature of this organism, death occurs in more than 10% of patients despite appropriate treatment. Another 15-20% suffer from permanent complications. (Kimmel, S. Prevention of meningococcal disease. Am Fam Physician 2005;72:2049-56)

Several subgroups, or serotypes, of N. meningitidis are responsible for infection. Serogroup B is the most common cause of meningitis in infants; no vaccine is currently available in the US. However, approximately 75% of the cases in this country—those involving mainly young adults and older individuals—are caused by serogroups C, Y, and W-135, all of which are contained in vaccines.

Who is At Risk for Meningococcal Meningitis?

Several groups of people are particularly susceptible to meningococcal infection:

• College students (particularly freshmen) living in dormitories
• Microbiologists who are routinely exposed to bacterial isolates
• Military recruits
• Persons who travel to or live in countries where meningococcal meningitis is “hyper-endemic” or epidemic
• Persons with deficiencies of terminal complement components (an immune deficiency)
• Persons with anatomic or functional asplenia (i.e., the spleen is not functioning properly or has been surgically removed)

What are the Signs of Meningococcal Meningitis?

Symptoms and signs of infection may appear suddenly and progress rapidly (infants may exhibit a more insidious onset):

• High fever (may be absent in infants)
• Headache
• Irritability/confusion
• Nausea/vomiting
• Neck stiffness
• Photophobia
• Lethargy, drowsiness
• Poor feeding or flaccidity in infants
• In infants, bulging fontanel (“soft spot”)
• Rash (hemorrhagic, purplish, splotchy)
• Seizures
• Coma

What is the Treatment for Meningococcal Meningitis?

Once meningitis is suspected, a patient is immediately started on intravenous antibiotics. A lumbar puncture (spinal tap) is performed to obtain fluid for accurate diagnosis. Sometimes, more than one puncture is performed to ensure that the antibiotic is working. Hospital stays can be prolonged, depending on whether a patient develops complications.

What are the Complications of Meningococcal Meningitis?

Possible complications include:

• Hearing loss
• Visual loss
• Limb amputation
• Organ failure (kidney, liver, adrenal, heart)
• Septicemia
• Disseminated intravascular coagulopathy (loss of the blood’s ability to clot normally)
• Shock
• Paralysis
• Learning disabilities/mental retardation
• Death

Can Meningococcal Meningitis be Prevented?

Vaccination

Two tetravalent vaccines are currently available for use in the US. The meningococcal conjugate vaccine (Menactra) confers better and longer-lasting immunity; it has been approved for use in individuals 11 to 55 years of age.

Vaccination is recommended in all high-risk groups and for all adolescents at 11 to 12 years of age. The vaccine is single-dose and costs about $100 (usually covered by insurance).

When Menactra is unavailable or when vaccination is indicated outside the recommended age ranges, a polysaccharide vaccine (Menomune) is effective. Though also a one-time immunization, it is available in multidose vials that contain thimerosal as a preservative or in preservative-free, single-dose vials.

Rare reports of Guillain-Barre´ syndrome associated with vaccination are being investigated by the Centers for Disease Control.

Prophylaxis

Antibiotic prophylaxis should be offered to individuals who have shared living quarters or had oral contact with an infected patient within the previous seven days. Oral rifampin is the optimal preventive antibiotic, but injections of other antibiotics are also effective. Candidates for prophylaxis are determined by health care professionals and local health departments.

Meningococcal meningitis is a serious, potentially fatal disease. With appropriate vaccination, 70 to 80% of US cases could probably be prevented.

The copyright of the article Meningococcal Meningitis in General Medicine is owned by Stephen Allen Christensen. Permission to republish Meningococcal Meningitis in print or online must be granted by the author in writing.

N. meningitidis, scanning electron micrograph

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