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Epidemiology of central nervous system infections in Olmsted County, Minnesota, 1950-1981
Abstract:
We identified all diagnosed cases of infections of the central nervous system (CNS), excluding poliomyelitis, in the population of Olmsted County, Minnesota, from 1950 to 1981 and described incidence, time trends, etiologic agents, and mortality for these infections. The adjusted incidence rate for bacterial meningitis was 8.6/100,000 person-years (with a case fatality ratio of 10%) and was highest in children less than five years of age; in this age-group, rates more than doubled from 1950 to 1981. The adjusted incidence rate of brain abscess was 1.1, with a case fatality ratio of 37%. The adjusted incidence rate of aseptic meningitis was 10.9/100,000 person-years. Age-specific rates were highest in children less than one year of age and in men, and increased during the study period. The adjusted incidence rate of viral encephalitis was 7.4, with a case fatality ratio of 3.8%. Rates were highest in children less than 10 years of age and in men. By 10 years of age, 0.9% of the men and 0.7% of the women were affected by a CNS infection. Cumulative incidence (risk) through age 80 was 2.3% for men and 1.5% for women.
Insights
Central nervous system (CNS) infections like bacterial meningitis and viral encephalitis are most common in young children and men. Incidence rates for these CNS infections increased from 1950 to 1981.
Area of Science:
- Neurology
- Infectious Diseases
- Epidemiology
Background:
- Infections of the central nervous system (CNS) represent a significant public health concern.
- Understanding the incidence, trends, and outcomes of CNS infections is crucial for developing effective prevention and treatment strategies.
Purpose of the Study:
- To identify and describe the incidence, time trends, etiologic agents, and mortality of CNS infections in Olmsted County, Minnesota, from 1950 to 1981.
- To analyze age-specific and sex-specific rates for bacterial meningitis, brain abscess, aseptic meningitis, and viral encephalitis.
Main Methods:
- Retrospective population-based study.
- Identification of all diagnosed cases of CNS infections (excluding poliomyelitis) in Olmsted County, Minnesota, between 1950 and 1981.
- Calculation of adjusted incidence rates, case fatality ratios, and cumulative incidence.
Main Results:
- Bacterial meningitis incidence was 8.6/100,000 person-years with a 10% case fatality ratio, highest in children under five, with rates doubling from 1950-1981.
- Brain abscess incidence was 1.1/100,000 person-years with a 37% case fatality ratio.
- Aseptic meningitis incidence was 10.9/100,000 person-years, with rates highest in infants and men, and increasing over time.
- Viral encephalitis incidence was 7.4/100,000 person-years with a 3.8% case fatality ratio, highest in children under 10 and men.
- Cumulative incidence through age 80 was 2.3% for men and 1.5% for women.
Conclusions:
- CNS infections, particularly bacterial meningitis and aseptic meningitis, show increasing incidence trends, especially in vulnerable populations like young children and men.
- While mortality rates vary by infection type, significant case fatality ratios persist, highlighting the need for continued research and intervention.
- Long-term cumulative risk indicates a notable proportion of the population experiences CNS infections by age 80.