Exploring the evolution of diversity in pathogen populations.

Pathogen biodiversity is an under-exploited source of inference regarding disease processes and the evolution of pathogens and pathogenesis. In addition, the structure of pathogen populations, especially for diverse organisms such as the meningococcus, has implications for public health interventions including vaccination and antibiotic use. The predominant paradigm for interpreting bacterial diversity has been the clonal population structure, which has been modified by the incorporation of the effects of horizontal genetic exchange. Multilocus models of variable antigens, which explore the effects of immune selection, provide alternative explanations for structured diversity in pathogen populations.