Listeria monocytogenes Dose Response Revisited—Incorporating Adjustments for Variability in Strain Virulence and Host Susceptibility

Abstract

Evaluations of Listeria monocytogenes dose-response relationships are crucially important for risk assessment and risk management, but are complicated by considerable variability across population subgroups and L. monocytogenes strains. Despite difficulties associated with the collection of adequate data from outbreak investigations or sporadic cases, the limitations of currently available animal models, and the inability to conduct human volunteer studies, some of the available data now allow refinements of the well-established exponential L. monocytogenes dose response to more adequately represent extremely susceptible population subgroups and highly virulent L. monocytogenes strains. Here, a model incorporating adjustments for variability in L. monocytogenes strain virulence and host susceptibility was derived for 11 population subgroups with similar underlying comorbidities using data from multiple sources, including human surveillance and food survey data. In light of the unique inherent properties of L. monocytogenes dose response, a lognormal-Poisson dose-response model was chosen, and proved able to reconcile dose-response relationships developed based on surveillance data with outbreak data. This model was compared to a classical beta-Poisson dose-response model, which was insufficiently flexible for modeling the specific case of L. monocytogenes dose-response relationships, especially in outbreak situations. Overall, the modeling results suggest that most listeriosis cases are linked to the ingestion of food contaminated with medium to high concentrations of L. monocytogenes. While additional data are needed to refine the derived model and to better characterize and quantify the variability in L. monocytogenes strain virulence and individual host susceptibility, the framework derived here represents a promising approach to more adequately characterize the risk of listeriosis in highly susceptible population subgroups.

Stakeholder meeting on the draft scientific opinion on Listeria monocytogenes contamination of ready‐to‐eat foods and the risk for human health in the EU

“…The focus was on the time period after the adoption of the previous Scientific Opinion of the BIOHAZ Panel at the end of 2007, i.e. 2008-2015(EFSA, 2008.…”

“…He informed that the Pouillot et al (2015) dose-response (DR) model incorporated the virulence and susceptibility variability for 11 population groups, suggesting that most human listeriosis cases are linked to the ingestion of food contaminated with medium to high concentrations of L. monocytogenes. On the other hand, cases might occur in a very susceptible person even when exposed to a low virulence strain.…”

Advancing risk assessment: mechanistic dose–response modelling ofListeria monocytogenesinfection in human populations

“…To compare the dose–response generated from the mechanistic model (3.1) with alternate dose–response models [17] that rely on human epidemiological data, we need appropriate values for these parameters. Recall that the population-level variation in model parameters naturally gives rise to the dose–response function governed by model (3.1).…”

Comparing listeriosis risks in at-risk populations using a user-friendly quantitative microbial risk assessment tool and epidemiological data

“…The general model was obtained from Ross et al [11], which was based on an exponential model [29]. Eleven dose-response models are used, each with previously derived subpopulation-specific distributions of R parameters (Table 2) [10]. The R parameters capture variability in subpopulations, within subpopulations, and in L. monocytogenes strains [10].…”

“…Dose-response models that incorporate L. monocytogenes strain variability have recently been developed for selected populations vulnerable to listeriosis [10], and could be integrated with demographic information to derive population-level estimates of risk. Ross et al [11] have estimated the prevalence of several at-risk subpopulations in Australia, but similar estimates have not yet been compiled for Canada.…”