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A quantitative microbial risk assessment model for Legionnaires' disease: animal model selection and dose-response modeling
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http://hdl.handle.net/1860/2687
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| Title: | A quantitative microbial risk assessment model for Legionnaires' disease: animal model selection and dose-response modeling |
| Authors: | Armstrong, T.W.
Haas, Charles Nathan |
| Keywords: | Microbial Risk Assessment
Dose Response Assessment
Legionella Pneumophila
Legionnaires’ Disease |
| Issue Date: | 2007 |
| Publisher: | Blackwell Publishing |
| Citation: | Risk Analysis, 27(6): pp. 1581-1596. |
| Abstract: | Legionnaires’ Disease (LD), first reported in 1976, is an atypical pneumonia caused by bacteria of the genus Legionella, and most frequently by L. pneumophila (Lp). Subsequent research on exposure to the organism employed various animal models, and with Quantitative Microbial Risk Assessment techniques, the animal model data may provide insights on human dose-response for LD. The present report focuses on the rationale for selection of the guinea pig model, comparison of the dose-response model results, comparison of projected low-dose responses for guinea pigs, and risk estimates for humans. Based on both in vivo and in vitro comparisons, the guinea pig (Cavia porcellus) dose-response data were selected for modeling human risk. We completed dose-response modeling for the β-Poisson (approximate and exact), exponential, probit, logistic and Weibull models for Lp inhalation mortality and infection (end point elevated body temperature) in guinea pigs. For mechanistic reasons, including low-dose exposure probability, further work on human risk estimates for LD employed the exponential and β-Poisson models. With an exposure of 10 Colony Forming Units (retained dose), the QMRA model predicted a mild infection risk of 0.4 (as evaluated by seroprevalence) and a clinical severity LD case (e.g., hospitalization and supportive care) risk of 0.0009. The calculated rates based on estimated human exposures for outbreaks used for the QMRA model validation are within an order of magnitude of the reported LD rates. These validation results suggest the LD QMRA animal model selection, dose-response modeling, and extension to human risk projections were appropriate. |
| URI: | http://hdl.handle.net/1860/2687 |
| Appears in Collections: | Faculty Research and Publications (CAEE)
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