Neisseria meningitidis (meningococcus) is a leading cause of bacterial meningitis and septicemia, with about 1.2 million cases of infection and 135,000 deaths globally each year. Because death can rapidly follow infection, cases should be considered a medical emergency.
Here are five things to know about meningococcal disease.
1. One in ten patients will die, even with treatment, so early diagnosis and treatment are critical.
The incidence of meningococcal disease in the United States is low, but because of its high mortality rate, early diagnosis and treatment are critical.
Even with antibiotic treatment, 1 in 10 people who get meningococcal disease will die from the infection, according to Richard Benson, a spokesperson at the Centers for Disease Control and Prevention (CDC). “Up to one in five patients who recover will have long-term disabilities, such as loss of limb(s), deafness, nervous system problems, or brain damage,” he added.
According to the CDC’s Yellow Book, about 40% of patients present with meningococcal sepsis (meningococcemia), which often involves hypotension, acute adrenal hemorrhage, and multiorgan failure. In infants and children younger than 2 years, the case-fatality rate is 10% to 20%, even with antibiotic treatment.
2. Certain groups are at higher risk for meningococcal disease.
Meningococcal disease is seasonal, with cases increasing in January, February, and March. Although people of any age can become infected, CDC surveillance data indicate that the incidence is highest in children younger than 1 year. A second peak occurs during adolescence. Risk factors include a previous recent viral infection, household crowding, and smoking. According to guidelines from the Advisory Committee on Immunization Practices, the following factors are associated with increased risk:
Persistent complement component deficiencies. Those with genetic deficiencies in the complement pathway (such as C3, C5–C9, properdin, factor D, or factor H) have up to a 10,000-fold increased risk.
Use of complement inhibitors. Use of eculizumab is associated with about a 2000-fold increased incidence of meningococcal disease. The risk remains even after vaccination.
Anatomic or functional asplenia, including sickle-cell disease.
HIV infection. Those with HIV infection or AIDS have an 11-fold to 24-fold increased risk for meningococcal disease.
High level of exposure. Microbiologists who are routinely exposed to N meningitidis isolates and travelers to countries where meningococcal disease is hyperendemic or epidemic are at greater risk.
Living in close quarters with others. Examples are college students and military recruits. An outbreak even occurred via a carnival discotheque.
Men who have sex with men. Incidence of disease is low but may be associated with HIV infection.
3. Most transmission is via asymptomatic carriers.
N meningitidis is commonly present in the flora of the nasopharynx, but for unknown reasons, nasopharynx colonization does not typically cause disease, resulting in asymptomatic carriage.
The disease is transmitted through direct large-droplet respiratory tract secretions from others, often from close contact with a carrier and generally not from individuals with invasive meningococcal disease. This highlights the key role of asymptomatic carriers in the disease process
4. A new vaccine has been approved for use.
Two meningococcal vaccines are no longer available in the United States: a quadrivalent meningococcal polysaccharide vaccine (MPSV4) and a combined Haemophilus influenzae type b and meningococcal vaccine (Hib-MenCY-TT).
5. In the case of an outbreak, follow CDC guidance.
The CDC offers guidance on steps to take in the case of a suspected outbreak. Highlights include the following:
All cases in a suspected outbreak of meningococcal disease should undergo thorough epidemiologic and laboratory investigation.
In outbreaks with well-defined risk groups, probable cases may be included as outbreak-associated even if they can’t be confirmed or the serogroup determined. The outbreak threshold for vaccine decision making should be determined on a case-by-case basis, using the general guidance.
If vaccination is undertaken, the vaccine(s) should be selected on the basis of outbreak serogroup.
Expanded antimicrobial chemoprophylaxis (ie, administration of antibiotics to a wider circle of individuals, not just close contacts of the case-patient)is typically not recommended as a stand-alone measure . However, in some organization-based outbreaks, this approach may be used in conjunction with vaccination or when vaccination is not possible. Antibiotic chemoprophylaxis is recommended for close contacts of patients with invasive meningococcal disease to prevent secondary cases.
The outbreak should be reevaluated 1 year after the last case for organization-based outbreaks to assess whether meningococcal disease risk is likely to again increase. For a community-based outbreak, a reassessment should be conducted 1 year after the last case to determine incidence.
Pippa Wysong is a freelance medical and science writer with over 30 years of experience writing for both medical and popular audiences. She is a former staffer at The Medical Post and has written numerous projects for Medscape.