PITTSBURGH, Aug. 7 – Adolescents and young adults have an unusually high risk of severe and sometimes fatal bacterial meningitis, according to a study led by the University of Pittsburgh Graduate School of Public Health (GSPH) and published in the Aug. 8 issue of the Journal of the American Medical Association.
In an effort to characterize, for the first time, the features of meningococcal infection in 15-to 24-year-olds during the 1990s, researchers conducted laboratory-based surveillance and reviewed 1990-1999 health department and medical records from the state of Maryland.
"We found that adolescents and young adults accounted for a relatively high proportion of all cases of meningococcal meningitis, and that infection in this age group led to death more often than expected," said study author Lee H. Harrison, M.D., associate professor of epidemiology at the GSPH and adjunct associate professor of international health at the Johns Hopkins Bloomberg School of Public Health.
"Traditionally, infants have been at the highest risk for meningococcal infection in developed countries, but during the 1990s there was an increase in the number of cases among adolescents and young adults," said Dr. Harrison, who also is head of the Infectious Diseases Epidemiology Research Unit at the University of Pittsburgh GSPH and School of Medicine. "Until now, the features of meningococcal infection in 15- to 24-year-olds during the 1990s have not been well characterized. This study demonstrates the importance of monitoring disease patterns -- such as changes in incidence among certain age groups and serogroup distribution -- with active, laboratory-based surveillance."
The investigators found 295 cases of meningococcal infection in Maryland from 1990 through 1999. Of those 295 cases, 71 (24.1 percent) occurred among people ages 15 to 24, and an unusually high number of these cases -- 16 cases, or 22.5 percent -- were fatal. Compared to patients age 25 and older, 15- to 24-year-old patients were more likely to be male; to smoke; to have meningitis; to have ecchymoses, a purple skin rash; and to have septic shock, a manifestation of severe bacterial infection. They were less likely to have a chronic medical condition.
The incidence of meningococcal infection in the 15- to 24-age group in the study population more than doubled between 1990 and 1997, rising from 0.9 to 2.1 cases per 100,000 people, and then dropped back to normal (1.0 per 100,000) in 1998-1999. About 83 percent of the cases in this age group, and a majority of cases in other age groups, were vaccine-preventable.
Meningitis is an inflammation of the membranes that cover the spinal cord and the brain. Bacterial meningitis, which is much more severe than viral meningitis, is caused by a variety of bacteria, one of which is Neisseria meningitidis, also known as the meningococcus.
Neisseria meningitidis is classified according to serogroup, which is based on the type of capsule surrounding the bacterium. Most cases of meningitis in the developed world are caused by organisms of serogroups B, C, Y and W135, while serogroup A organisms cause most cases in the developing world. The meningococcal vaccine is based on serogroup. Meningococcal meningitis of all serogroups can lead to disability and death. The majority of 15- to 24-year-olds in this study had serogroup C infection.
The study was funded by the Centers for Disease Control and Prevention, Aventis Pasteur and the State of Maryland. The research team included investigators from the University of Pittsburgh, Johns Hopkins University, the Centers for Disease Control and Prevention and the Maryland Department of Health and Mental Hygiene.
Materials provided by University Of Pittsburgh Medical Center. Note: Content may be edited for style and length.
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