Meningococcal carriage and disease--population biology and evolution
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Published on: November 5, 2019
Dominique A Caugant1, Martin C J Maiden
1WHO Collaborating Centre for Reference and Research on Meningococci, Norwegian Institute of Public Health, Oslo, Norway. dominique.caugant@fhi.no
Abstract:
Meningococcal disease occurs worldwide with incidence rates varying from 1 to 1000 cases per 100,000. The causative organism, Neisseria meningitidis, is an obligate commensal of humans, which normally colonizes the mucosa of the upper respiratory tract without causing invasive disease, a phenomenon known as carriage. Studies using molecular methods have demonstrated the extensive genetic diversity of meningocococci isolated from carriers, in contrast to a limited number of genetic types, known as the hyperinvasive lineages, associated with invasive disease. Population and evolutionary models that invoke positive selection can be used to resolve the apparent paradox of virulent lineages persisting during the global spread of a non-clonal and normally commensal bacterium. The application of insights gained from studies of meningococcal population biology and evolution is important in understanding the spread of disease, as well as in vaccine development and implementation, especially with regard to the challenge of producing comprehensive vaccines based on sub-capsular antigens and measuring their effectiveness.
Insights
Meningococcal disease, caused by Neisseria meningitidis, presents a paradox of virulent strains persisting despite widespread carriage. Evolutionary models help explain this, aiding vaccine development for better disease control.
Area of Science:
- Microbiology
- Evolutionary Biology
- Epidemiology
Background:
- Meningococcal disease is a global health concern with variable incidence.
- Neisseria meningitidis, the causative agent, is a human commensal, typically causing asymptomatic carriage in the upper respiratory tract.
- Genetic diversity exists among meningococci, with specific hyperinvasive lineages linked to invasive disease.
Purpose of the Study:
- To resolve the paradox of virulent meningococcal lineages persisting during widespread carriage.
- To apply population and evolutionary models to understand bacterial spread and virulence.
- To inform vaccine development and implementation strategies.
Main Methods:
- Utilized molecular methods to analyze genetic diversity of Neisseria meningitidis.
- Employed population and evolutionary models, including positive selection dynamics.
- Examined insights from meningococcal population biology and evolution studies.
Main Results:
- Demonstrated extensive genetic diversity in meningococci from carriers.
- Identified a limited number of hyperinvasive lineages associated with invasive disease.
- Showcased the utility of evolutionary models in explaining pathogen persistence and spread.
Conclusions:
- Population and evolutionary dynamics, particularly positive selection, explain the persistence of virulent meningococcal lineages.
- Understanding meningococcal evolution is crucial for predicting disease spread.
- Insights are vital for developing effective vaccines, including those targeting sub-capsular antigens.
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