Meningococcal meningitis is one of the three most common types of bacterial meningitis. The incubation period averages 3-4 days (range 1-10 days), which is the period of communicability. It progresses more rapidly than any other acute form of bacterial meningitis. Meningococcal meningitis involves the central nervous system. In adults and children it is often preceded by respiratory illness or a sore throat. In its acute form, the disorder is characterized by fever, headache, a stiff neck, nausea, vomiting and altered mental state such as confusion or coma. Adults may become seriously ill within hours. In children the course of the infection may be even shorter.
Meningococcal meningitis evolves when the bacteria, Neisseria meningitidis (N.meningitidis) progresses from initial adherence to the nasopharyngeal (nose and throat) mucosa to invasion of the deeper mucosal layers (the submucosa). These bacteria rapidly multiply, and can lead to a mild (subclinical) infection. However, in approximately 10-20% of cases, the N.meningitidis enters the bloodstream (meningococcemia). This systemic form of the disease, meningococcemia, usually precedes the development of meningococcal meningitis by 24-48 hours.
Meningococcemia is characterized by severe, widespread vascular injury, with evidence of circulatory collapse and disseminated intravascular coagulation (DIC) Skin rashes occur in about half of all individuals with meningococcal meningitis. The rash is petechial (tiny, non-raised, purple-reddish lesions that do not blanch when pressed, and are the result of areas of intravascular bleeding.
Swelling or inflammation of the brain (cerebral edema or ventriculitis), or hydrocephalus (accumulation of fluid in the brain cavity) may also occur. Additional symptoms may include chills; sweating; weakness; loss of appetite; muscle pain (myalgia) of the lower back or legs; or inability to tolerate bright light (photophobia). (For more information on hydrocephalus, choose “hydrocephalus” as your search term in the Rare Disease Database).
Dehydration often occurs in individuals with meningococcal meningitis. In some cases, collapse of the blood vessels may lead to shock (Waterhouse-Friderichsen syndrome) when the meningococcus bacteria spread to the blood (septicemia). Later symptoms may include paralysis of one side of the body (hemiparesis), hearing loss, or additional neurological abnormalities.
The course of meningococcal meningitis is less predictable among infants between three months and two years of age. Fever, refusal of feedings, vomiting, irritability, and convulsions usually occur. A high-pitched cry and a bulging or tight soft spot (fontanel) on the crown of the head (where the parts of the skull’s still unhardened bones join) may also occur. Since the incidence of most types of meningitis is highest among this age group, any unexplained fever needs to be closely watched. Cerebral fluid may accumulate just inside the tough outer membrane covering the brain (subdural effusions) after several days. Warning signs may include seizures, a persistent fever, and an enlarging head size. A brain abscess or subdural pus accumulation may also occur. Water accumulating in the brain (hydrocephalus), deafness and slowed mental and physical development are possible consequences of meningitis.
Meningococcal meningitis is caused by a bacterium known as Neisseria meningitidis. There are several types, or serogroups, of Neisseria meningitidis. The most common of these serogroups are A, B, C, D, X, Y, 29E, and W135. Serogroups A, B, C, and Y are responsible for most meningococcal diseases.
The bacterium is spread by droplets in the air or close contact with an infected person. It collects in the nasopharynx, or post-nasal space, that connects the nasal cavities with the throat. The bacterium is transported to the membranes (meninges) around the brain or spinal cord by the blood. It usually spreads from nearby infected areas such as the nasal sinuses or from the cerebrospinal fluid.
Meningococcal meningitis primarily affects infants, children, and young adults. Males are affected slightly more than females, and account for 55% of all cases, with an incidence of 1.2 cases per 100,000 population, compared to 1 case per 100,000 population among females. Meningococcal meningitis can occur as an epidemic in subgroups such as people in the military services or students in dormitories. Vaccines can help control meningitis epidemics caused by serogroups A, B, C, Y, or W135.
The age-specific incidence of meningococcal disease is highest in young children, although the incidence of meningococcal disease in adolescents and college-aged young adults appears to have increased. College students living in dormitories seem to be the population at the most increased risk. This is due to the close proximity of students in college dormitories, which allows for faster spread of infection.
Testing for meningococcal meningitis may include imaging techniques such as CT scans or magnetic resonance imaging (MRI). Other testing may include examination of the blood and/or skin. Diagnosis is made by laboratory examination of the cerebrospinal fluid that often reveals the presence of bacterial meningitis.
There are 5 subtypes of N. meningitidis. Currently, (as of June, 2012) licensed vaccines for prevention of illness from 4 of the 5 subtypes exists. The vaccines are called Menveo, Menactra and Nimerix. Vaccines with narrow coverage have been used against serogroup B, and a vaccine with broad coverage is in late stage of development. Public health officials recommend that all college students take the meningococcal meningitis immunization. In particular, those who live in close quarters (dormitories, fraternities, and sororities), who frequent bars or consume alcohol, who smoke or are regularly around smokers are at higher risk and should consider vaccination. Students with certain chronic conditions (eg, have had their spleen removed) should be vaccinated. Students traveling to high-risk areas of the world (eg, sub-Sahara Africa) should consider vaccination. The conjugate vaccine is now also recommended for all children when they reach 11-12 years of age.
Meningococcal meningitis is usually treated with antibiotic drugs, administered intravenously, against the bacteria causing the infection. Initial treatment should always comprise a new generation cephalosporin (with or without Vancomycin) plus dexamethasone unless the patient is already under a specific antibiotic regimen.
The use of penicillins is limited due to their suboptimal penetration into the CSF. Early intravenous administration of dexamethasone is currently recommended as adjunctive therapy in an attempt to diminish the rate of permanent neurological sequelae. Antibiotic treatment is modified based on the CSF culture and antibiotic sensibility studies.
Family members of those infected can be treated with Rifampin as a preventative measure; however, for pregnant women, ceftriaxone is recommended.
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Contact for additional information about meningococcal meningitis:
Rino Rappuoli, PhD
Global Head Vaccines Research
Novartis Vaccines and Diagnostics Srl
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53100 Siena, Italy
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