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Notice to Readers: Changes to Data Presented in Tables I and II

This issue of MMWR incorporates modifications to Tables I and II, Provisional Cases of Selected Notifiable Diseases, United States. This year, the modifications add serogroup data to the meningococcal disease category reported in Table II and broaden domestic arboviral disease data presented in Tables I and II to include both neuroinvasive and non-neuroinvasive illness.

Meningococcal Disease Data

Meningococcal disease is nationally reportable and the cumulative (year-to-date) incidence data for the current and preceding year are reported by state in Table II. Confirmed cases are those in which Neisseria meningitidis is isolated from a normally sterile site (e.g., blood or cerebrospinal fluid [CSF] or less commonly, joint, pleural, or pericardial fluid) (1). Probable cases of meningococcal disease include those with a positive antigen test in CSF or clinical purpura fulminans in the absence of a positive blood culture.

Most meningococcal disease in the United States is caused by N. meningitidis belonging to one of three serogroups, B, C, and Y, which caused 23%, 31%, and 39% of reported cases, respectively, during 1996--2001 (2). Two additional serogroups, A and W-135, are important causes of disease in other parts of the world. Disease caused by four of these serogroups, A, C, Y, and W-135 can be prevented by vaccination with a quadrivalent meningococcal polysaccharide vaccine marketed in the United States as Menomune®. However, this vaccine is not routinely used in the general U.S. population because of its poor immunogenicity in children, short duration of protection, and inability to induce herd immunity (2). A new, quadrivalent A/C/Y/W-135 protein-conjugate vaccine might become available in the United States in 2005 for persons aged 11--55 years. The vaccine is expected to have improved immunogenicity in young children, provide longer-lasting immunity, and might provide herd immunity if used in certain strategies. The Advisory Committee on Immunization Practices is considering recommendations for its use. Other meningococcal conjugate vaccines, with different formulations, combinations, and target age groups are expected to be available within the next 5 years.

To monitor changes in the incidence of vaccine-preventable meningococcal disease, meningococcal disease reports should include serogroup information. However, in 2003, only 459 (26.0%) of 1,768 cases of meningococcal disease reported to CDC included this information. To encourage serogroup reporting, the Council of State and Territorial Epidemiologists (CSTE) recommends that state, territorial, and local health departments encourage bacterial culture for all suspected cases of meningococcal invasive disease and that every isolate of N. meningitidis from normally sterile sites be serogrouped. CSTE further recommends that state, territorial, and local health departments collect serogroup information for all reported cases and report this information to CDC (3).

Beginning with this issue, meningococcal disease data reported in Table II will be presented in five columns under the headings "All Serogroups," "Serogroup A, C, Y, W-135," "Serogroup B," "Other serogroup," and "Serogroup unknown." These changes are intended to stimulate more complete serogroup reporting and will make Table II more informative by permiting the data to be used for monitoring the impact of vaccine interventions on the incidence of meningococcal disease.

Domestic Arboviral Disease Data

At its 2004 meeting, CSTE broadened the surveillance case definition for domestic arboviral diseases to include both neuroinvasive and non-neuroinvasive illness (4). For each low-incidence domestic arbovirus (California serogroup, eastern and western equine, Powassan, and St. Louis encephalitis viruses), neuroinvasive and non-neuroinvasive disease reports meeting the revised case definition will be combined and continue to appear in Table I. Case reports of West Nile virus disease will continue to appear in Table II, with separate columns for neuroinvasive and non-neuroinvasive disease, consistent with the revised case definition.


  1. CDC. Case definitions for infectious conditions under public health surveillance. MMWR 1997;46(No. RR-10):24.
  2. Raghunathan PL, Bernhardt SA, Rosenstein NE. Opportunities for control of meningococcal disease in the United States. Annu Rev Med 2004;55:333--53.
  3. Council of State and Territorial Epidemiologists. Position statement 04-ID-08: meningococcal serogroup surveillance. Available at
  4. Council of State and Territorial Epidemiologists. Position statement 04-ID-01: revision of national surveillance case definition of disease caused by neurotropic domestic aboviruses, including the addition to the NNDSS of non-neuroinvasive illnesses caused by these viruses. Available at

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