Expanding the Pathogenic Potential Concept To Incorporate Fulminancy, Time, and Virulence Factors

The pathogenic potential (PP) concept posits that all microorganisms have some pathogenic potential that can be calculated by an equation that includes the fraction symptomatic, inoculum, and mortality fraction. The PP concept dispenses with characterizing microbes as pathogens, nonpathogens, commensals, pathobionts, etc., by providing an alternative approach to the problem of virulence that considers the contributions of both the host and the microbe. Here, the PP concept is extended to incorporate the role of time in virulence by introducing a new parameter, fulminancy, which is a measure of the rapidity of the pathogenic process. Fulminancy allows PP calculations in situations where all hosts are affected equally, but the process occurs later for attenuated strains. Differences in the PP of wild-type and mutant microbes lacking virulence factors can be used to estimate the contribution of virulence factors to the pathogenic process, thus providing a new quantitative approach to these important pathogenicity parameters.