A death from meningococcal disease, occurring as it often does in otherwise healthy adolescents, is devastating to the family and the community and elicits strong demands for preventive measures, according to an article in the October 5 issue of the New England Journal of Medicine.
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 Two important questions arise in the wake of such a tragedy, says Dr. Pierce Gardner. Should the patient have previously received meningococcal vaccine? And what measures should be taken to protect his close contacts and his community?

To help with answering those questions and others, Gardner sketches what is known about invasive meningococcal disease.

• The underlying infectious agent, the bacterium Neisseria meningitidis, colonizes the nasopharynx in humans and is transmitted by direct contact with large-droplet respiratory secretions;
• The disease often appears in a new environment of crowded conditions; of 76 outbreaks identified in the United States during an 8-year period, 65 percent occurred in colleges and universities, primary and secondary schools, and nursing homes;
• The interval between acquisition of the organism and clinical infection is very short—often 10 days or less;
• Invasive meningococcal disease is uncommon in the United States, but the fatality rate is high (approximately 10 percent) and up to 20 percent of survivors have  neurologic damage or other complications;
• There are five sergroups (A, B, C, Y, and W-135), with B, C, and Y dominant in the United States.

Two meningococcal vaccines are licensed for use in the United States. Both provide antigens against serogroups A, C, Y, and W-135, but unfortunately neither protects against serogroup B, which is responsible for one-third of cases.

One of the vaccines, Menomume, made by Sanofi Pasteur, has been available for 25 years. The vaccine is considered safe but has some limitations—the duration of protection is short (three to five years in adolescents and adults). It’s sometimes recommended for persons needing short-term protection--travelers to regions where the meningococcal disease is endemic, for example.

The second vaccine, Menactra, also made by Sanofi Pasteur, was approved in January 2005 for use in persons 11 to 55 years of age. It contains the same antigens as the earlier vaccine, plus diphtheria toxoid. It’s expected to provide more durable protection than the earlier vaccine and to be more effective in establishing herd immunity. The Advisory Committee on Immunization Practices now recommends that all adolescents be immunized with the newer vaccine, beginning with children 11 to 12 years of age, with a catch-up immunization at the time of high school entry for persons not previously vaccinated.

Dr. Gardner notes that if the strategy of vaccinating all children 11 to 12 years of age were fully implemented, plus the high school catch-up, everyone 11 to 19 years old would be immunized by the year 2008 against meningococcal disease caused by subgroups A, C, Y, and W-135.

Protecting Contacts

The question immediately confronting schools and public health officials when a case of meningococcal infection is identified is how to keep one case from becoming an outbreak. "The most urgent priority," Dr. Gardner writes, "is to treat the patient’s close contacts with an effective antimicrobial agent." The CDC maintains a list of recommended antimicrobials for use in that situation.

The definition isn’t precise, but "close contact" does not include classmates or co-workers, unless they were in close proximity (three feet or less) to the patient for eight hours or more, or were directly exposed to the patient’s oral secretions through kissing, mouth-to-mouth resuscitation, or management of an endotracheal tube. More likely to be close contacts are members of the patient’s household, roommates, and anyone who sat next to the patient on an airplane for more than eight hours.

Summing up, Dr. Gardner notes that challenges to creating a comprehensive immunization program for meningococcal disease include the lack of serogroup B coverage in current vaccines, difficulties in reaching adolescent populations, and vaccine shortages. But he suggests that the anxiety caused by even one case "provides an opportunity to promote community compliance with current recommendations."

Editor’s note: There are two forms of meningitis, one caused by bacteria and the other viral. Dr. Gardner’s article deals with the bacterial form. Viral meningitis, a less severe form of the illness, is often mistaken for the flu; patients normally recover in a week or so without treatment.

The article "Prevention of Meningococcal Disease" was published in the October 5, 2006, issue of the New England Journal of Medicine, which can be reached at http://content.nejm.org.