Neisseria meningitides : Secular Trends in the United States
During 2005-2011, an estimated 800-1,200 cases of meningococcal disease occurred annually in the United States, representing an incidence of 0.3 cases per 100,000 population. Incidence has declined annually since a peak of disease in the late 1990s. Since 2005, declines have occurred among all age groups and in all vaccine-contained serogroups.
In addition, incidence of disease attributable to serogroup B, a serogroup not included in the quadrivalent vaccine, declined for reasons that are not known. Serogroups B, C, and Y are the major causes of meningococcal disease in the United States, each being responsible for approximately one third of cases. The proportion of cases caused by each serogroup varies by age group. Approximately 60% of disease among children aged 0 through 59 months is caused by serogroup B, for which no conjugate vaccine is licensed or available in the United States. Serogroups C, W, or Y, which are included in vaccines available in the United States, cause 73% of all cases of meningococcal disease among persons 11 years of age or older.
The incidence of serogroups C and Y, which represent the majority of cases of meningococcal disease preventable by the conjugate vaccines, are at historic lows. However, a peak in disease incidence among adolescents and young adults 16 to 21 years of age has persisted, even after routine vaccination of adolescents was recommended in 2005. From 2000–2004 to 2005–2009, the estimated annual number of cases of serogroups C and Y meningococcal disease decreased 74% among persons aged 11 through 14 years but only 27% among persons aged 15 through 18 years.
During 2006-2010 (i.e., in the first 5 years after routine use of meningococcal vaccine was recommended) CDC received reports of approximately 30 cases of serogroups C and Y meningococcal disease among persons who had received the vaccine. The case-fatality ratio was similar among persons who had received vaccine compared with those who were unvaccinated. Of the 13 reports of breakthrough disease for which data on underlying conditions were available, four persons had underlying conditions or behaviors associated with increased risk for bacterial infections, including 1) Type 1 diabetes mellitus; 2) current smoking; 3) history of bacterial meningitis and recurrent infections; and 4) aplastic anemia, paroxysmal nocturnal hemoglobinuria, and receipt of eculizumab (which blocks complement protein C5).
Neisseria meningitides: Clinical Features, Laboratory Diagnosis, and Medical Management
In the United States, meningococcal outbreaks account for less than 2% of reported cases (98% of cases are sporadic). However, outbreaks of meningococcal disease continue to occur. During 2010, 2 serogroup C and 2 serogroup B outbreaks were reported to CDC. Cases associated with all reported outbreaks accounted for 108 (1.5%) of the 7,343 cases reported to CDC during 2005-2011. See www.cdc. gov/mmwr/pdf/rr/rr6202.pdf for additional information on the evaluation and management of meningococcal outbreaks.
Historically, large epidemics of serogroup A meningococcal disease occur in the African “meningitis belt,” an area that extends from Ethiopia to Senegal. Rates of endemic meningococcal disease in this area are several times higher than in industrialized countries. In each epidemic, tens of thousands of cases and thousands of deaths may occur. Approximately 350 million people are at risk. The phased introduction in meningitis belt countries of MenAfriVac, a novel serogroup A meningococcal conjugate vaccine which is being implemented through preventive national campaigns of all individuals 1-29 years of age, holds great promise to end epidemic meningitis as a public health concern by 2016.
Neisseria meningitides : Secular Trends in the United States,Neisseria meningitides,Secular Trends, Secular Trends in the United States,Neisseria meningitides : Secular Trends in the United States
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