Hierarchical dose response of E. coli O157:H7 from human outbreaks incorporating heterogeneity in exposure.
The infectivity of pathogenic microorganisms is a key factor in the transmission of an infectious disease in a susceptible population. Microbial infectivity is generally estimated from dose-response studies in human volunteers. This can only be done with mildly pathogenic organisms. Here a hierarchical Beta-Poisson dose-response model is developed utilizing data from human outbreaks. On the lowest level each outbreak is modelled separately and these are then combined at a second level to produce a group dose-response relation. The distribution of foodborne pathogens often shows strong heterogeneity and this is incorporated by introducing an additional parameter to the dose-response model, accounting for the degree of overdispersion relative to Poisson distribution. It was found that heterogeneity considerably influences the shape of the dose-response relationship and increases uncertainty in predicted risk. This uncertainty is greater than previously reported surrogate and outbreak models using a single level of analysis. Monte Carlo parameter samples (alpha, beta of the Beta-Poisson model) can be readily incorporated in risk assessment models built using tools such as S-plus and @ Risk.
National Institute of Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, Bilthoven, The Netherlands. Peter.Teunis@rivm.nl
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PF
Teunis
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ID
Ogden
N J C
NJ
Strachan
D000328:Adult; D002648:Child; D004196:Disease Outbreaks; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission*; D019453:Escherichia coli O157 / Q000302:isolation & purification* / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D007564:Japan / Q000453:epidemiology; D015233:Models, Statistical; D009010:Monte Carlo Method; D018570:Risk Assessment; D006113:United Kingdom / Q000453:epidemiology; D014481:United States / Q000453:epidemiology