Laboratory-based surveillance for meningococcal disease in selected areas, United States, 1989-1991.

PROBLEM/CONDITION: Neisseria meningitidis is a leading cause of bacterial meningitis and septicemia in the United States. Accurate surveillance for meningococcal disease is required to detect trends in patient characteristics, antibiotic resistance, and serogroup-specific incidence of disease.

REPORTING PERIOD COVERED

January 1989 through December 1991.

DESCRIPTION OF SYSTEM

A case of meningococcal disease was defined by the isolation of N. meningitidis from a normally sterile site, such as blood or cerebrospinal fluid, in a resident of a surveillance area. Cases were reported by personnel in each hospital laboratory in the surveillance areas. The surveillance areas consisted of three counties in the San Francisco metropolitan area, eight counties in the Atlanta metropolitan area, four counties in Tennessee, and the entire state of Oklahoma.

RESULTS

Age- and race-adjusted projections of the U.S. population suggest that approximately 2,600 cases of meningococcal disease occurred annually in the United States. The case-fatality rate was 12%. Incidence declined from 1.3/100,000 in 1989 to 0.9/100,000 in 1991. Seasonal variation occurred, with the highest attack rates in February and March and the lowest in September. The highest rates of disease were among infants, with 46% of cases affecting those < or = 2 years of age. Males accounted for 55% of total cases, with an incidence of 1.2/100,000, compared with 1.0/100,000 among females (relative risk (RR) = 1.3, 95% confidence interval (CI) 1.0-1.6). The incidence was significantly higher among blacks (1.5/100,000) than whites (1.1/100,000) (RR = 1.4 [95% CI 1.1-1.8]). Serogroup B caused 46% of cases and serogroup C, 45% Thirty-eight percent of isolates were reported to be resistant to sulfa; none were reported to be resistant to rifampin.

INTERPRETATION

The decline in incidence of meningococcal disease from 1989 through 1991 cannot be explained by any change in public health control measures; this trend should be monitored by continued surveillance. The age, sex, and race distribution and seasonality of cases are consistent with previous reports. The proportion of N. meningitidis isolates resistant to sulfa continues to be substantial. A relatively small proportion of cases is potentially preventable by the use of the currently available polysaccharide vaccine, which induces protection against serogroups, A, C, Y, and W135 and is effective only for persons > 2 years of age.

ACTIONS TAKEN

Current recommendations against the use of sulfa drugs for treatment or prophylaxis of meningococcal disease unless the organism is known to be sensitive to sulfa should be continued. Since resistance to rifampin is rarely reported, it continues to be the drug of choice for prophylaxis. The development of vaccines effective for infants and vaccines inducing protection against serogroup B would be expected to have a substantial impact on disease.