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Group A meningococcal disease in the U.S. Pacific Northwest: epidemiology, clinical features, and effect of a
Abstract:
In 1975 an outbreak of group A meningococcal disease began in Seattle, Washington, and cases subsequently were recognized throughout the Pacific Northwest. Nearly one-half of the affected persons were Native Americans; two-thirds were alcohol abusers and/or habitués of skid road communities. In Seattle, group A meningococci colonized asymptomatic persons only if these individuals had contact with skid road (P = .006). The epidemic strain may have spread from American Indians in Manitoba, Canada. Traditional migration routes connect the two populations; asymptomatic American Indians on reservations in Washington carried group A meningococci. Vaccination programs were undertaken in four cities but only after cases occurred. In Seattle, vaccination reached 80% of the target population and was associated with a significant decrease in incidence of the disease, but cases recurred after the program ended. The social habits of skid road communities, combined with the "case-triggering" approach to, and premature termination of, vaccination programs, may have resulted in 56% of regional cases occurring after the start of the vaccination program in Seattle.
Insights
An outbreak of group A meningococcal disease in the Pacific Northwest disproportionately affected Native Americans and those in skid road communities. Vaccination efforts showed temporary success but were hampered by reactive strategies and early termination, leading to disease recurrence.
Area of Science:
- Epidemiology
- Infectious Disease Control
Background:
- Group A meningococcal disease outbreak identified in Seattle, 1975, spreading throughout the Pacific Northwest.
- Affected populations included a high proportion of Native Americans and individuals from skid road communities, with a significant association between colonization and skid road contact.
Purpose of the Study:
- To investigate the epidemiology of the group A meningococcal disease outbreak.
- To analyze the impact of social factors and vaccination strategies on disease incidence and recurrence.
Main Methods:
- Retrospective analysis of outbreak data, including demographic information and vaccination program outcomes.
- Epidemiological investigation of asymptomatic carriers and potential transmission routes.
Main Results:
- Group A meningococci colonized asymptomatic individuals with skid road contact (P = .006).
- Vaccination in Seattle reached 80% of the target population, significantly reducing incidence.
- Disease cases recurred after vaccination program termination, with 56% of regional cases occurring post-vaccination program initiation.
Conclusions:
- The social dynamics of skid road communities and reactive, prematurely terminated vaccination programs contributed to the sustained and recurrent nature of the meningococcal outbreak.
- Targeted interventions and sustained vaccination efforts are crucial for effective control of meningococcal disease in vulnerable populations.