【新英格兰】Bacterial Meningitis in the United States, 1998–2007
BackgroundThe rate of bacterial meningitis declined by 55% in the United States in the early
1990s, when the Haemophilus influenzae type b (Hib) conjugate vaccine for infants was
introduced. More recent prevention measures such as the pneumococcal conjugate
vaccine and universal screening of pregnant women for group B streptococcus (GBS)
have further changed the epidemiology of bacterial meningitis.
Methods
We analyzed data on cases of bacterial meningitis reported among residents in eight
surveillance areas of the Emerging Infections Programs Network, consisting of approximately
17.4 million persons, during 1998–2007. We defined bacterial meningitis
as the presence of H. influenzae, Streptococcus pneumoniae, GBS, Listeria monocytogenes, or
Neisseria meningitidis in cerebrospinal fluid or other normally sterile site in association
with a clinical diagnosis of meningitis.
Results
We identified 3188 patients with bacterial meningitis; of 3155 patients for whom
outcome data were available, 466 (14.8%) died. The incidence of meningitis changed
by −31% (95% confidence interval , −33 to −29) during the surveillance period,
from 2.00 cases per 100,000 population (95% CI, 1.85 to 2.15) in 1998–1999 to 1.38
cases per 100,000 population (95% CI 1.27 to 1.50) in 2006–2007. The median age of
patients increased from 30.3 years in 1998–1999 to 41.9 years in 2006–2007 (P<0.001
by the Wilcoxon rank-sum test). The case fatality rate did not change significantly:
it was 15.7% in 1998–1999 and 14.3% in 2006–2007 (P = 0.50). Of the 1670 cases reported
during 2003–2007, S. pneumoniae was the predominant infective species (58.0%),
followed by GBS (18.1%), N. meningitidis (13.9%), H. influenzae (6.7%), and L. monocytogenes
(3.4%). An estimated 4100 cases and 500 deaths from bacterial meningitis
occurred annually in the United States during 2003–2007.
Conclusions
The rates of bacterial meningitis have decreased since 1998, but the disease still often
results in death. With the success of pneumococcal and Hib conjugate vaccines in
reducing the risk of meningitis among young children, the burden of bacterial meningitis
is now borne more by older adults. (Funded by the Emerging Infections Programs,
Centers for Disease Control and Prevention.)
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