scholarly journals Legionnaires' disease: evaluation of a quantitative microbial risk assessment model

2008 ◽  
Vol 6 (2) ◽  
pp. 149-166 ◽  
Author(s):  
Thomas W. Armstrong ◽  
Charles N. Haas
Keyword(s):  
Risk Assessment ◽  
Natural Waters ◽  
Hot Water ◽  
Assessment Model ◽  
Clinical Severity ◽  
Cooling Towers ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Legionnaires Disease

Background: The quantities of Legionella vary considerably from natural waters to water in contaminated domestic hot water supplies, whirlpool spas and cooling towers, with the risk for LD rising as the Legionella counts grow. We currently report the results from our Quantitative Microbial Risk Assessment (QMRA) model evaluation. We developed the LD QMRA model to better understand Legionella exposure risks. Methods: Using an animal data derived model for LD, we calculated risks from estimated exposures for a whirlpool spa outbreak, two hot spring spa outbreaks and compared the results to the reported LD risks. Results: The QMRA model shows agreement (generally less than an order of magnitude discrepancy) with the reported Legionnaires' disease sub-clinical severity infection, clinical severity infection, and mortality risks. Conclusions: The LD QMRA model may lead to risk based limits to supplement the current guidance on Legionella control in cooling towers, whirlpool spas and other potential exposure sources. The verification of QMRA for LD also suggests the techniques, given suitable animal model data, may be useful in quantifying human response to other airborne pathogens.

Comparing the Effect of Various Contamination Levels for Salmonella in Chicken Meat Preparations on the Probability of Illness in Belgium

2009 ◽  
Vol 72 (10) ◽  
pp. 2093-2105 ◽  
Author(s):  
MIEKE UYTTENDAELE ◽  
KATLEEN BAERT ◽  
KOEN GRIJSPEERDT ◽  
LIEVEN DE ZUTTER ◽  
BENOIT HORION ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Chicken Meat ◽  
Assessment Model ◽  
Contamination Level ◽  
Quantitative Microbial Risk Assessment ◽  
Risk Assessment Model ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Increased Risk ◽  
Fixed Input

At the urging of competent national authorities, a limited risk assessment on Salmonella in chicken meat preparations in Belgium was undertaken following a retail-to-table approach. The input distribution of Salmonella was based on surveillance data in Belgium. To analyze the relative impact of reducing the risk of salmonellosis associated with a decrease in the Salmonella contamination level, different distributions based on the actual situation but limiting the number of portions containing Salmonella at 1 CFU per 1, 10, and 25 g of meat were used in the quantitative microbial risk assessment model. The quantitative microbial risk assessment model also was run several times with a theoretical fixed input of Salmonella assuming all portions possessed the same fixed contamination level set at 1,000, 100, 10, and 1 CFU/g of meat and 1 CFU per 10, 25, 100, and 1,000 g of meat. With regard to the initial contamination level, the results indicate, both by the narrowing of the current distribution and by the fixed input, that especially the higher levels of contamination (>1 CFU/g) contribute to the increased risk for salmonellosis.

scholarly journals Evaluating the Risk of Salmonellosis from Dry Roasted Sunflower Seeds

2019 ◽  
Vol 83 (1) ◽  
pp. 17-27 ◽  
Author(s):  
BALASUBRAHMANYAM KOTTAPALLI ◽  
STEPHANIE P. V. NGUYEN ◽  
KELLY DAWSON ◽  
KAITLYN CASULLI ◽  
CATE KNOCKENHAUER ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Water Activity ◽  
The United States ◽  
Arithmetic Mean ◽  
Assessment Model ◽  
Quantitative Microbial Risk Assessment ◽  
Sunflower Seeds ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Log Reduction

ABSTRACT Outbreaks and recalls related to nuts and seeds in the United States have increased recently, and 80% of these recalls are due to Salmonella. The U.S. Food and Drug Administration's Food Safety Modernization Act requires food manufacturers to implement risk-based preventive controls based on scientific and technical evidence. Data are limited on the inactivation of Salmonella during processing of saltwater brined in-shell sunflower seeds. The goal of this research was to validate the adequacy of roasting in controlling Salmonella during the production of sunflower seeds and to assess the resulting risk. Four Salmonella strains were inoculated onto sunflower seeds and processed to simulate commercial manufacturing. Seeds were tumbled and roasted at 225°F (107.2°C) and 275°F (135°C) for roasting times from 5 to 45 min. Regression models for Salmonella inactivation and water activity change were developed. The inactivation model predicted a 5-log reduction in Salmonella when sunflower seeds were roasted at 135°C for 19.2 min, with a corresponding water activity of ∼0.61. Roasted sunflower seeds are typically not saleable at water activities >0.6 due to quality issues. Saleable water activities (0.03 to 0.04) were only achieved when the sunflower seeds were roasted for 45 min at 135°C, which resulted in a >7-log reduction in Salmonella. A quantitative microbial risk assessment based on literature values, expert opinion, and the above-mentioned models was used to predict risk of salmonellosis from sunflower seeds. The quantitative microbial risk assessment model predicted an arithmetic mean probability of illness of 1.45E−07 per 28-g serving based on roasting at 135°C for 20 min and an arithmetic mean probability of illness of 5.46E−10 per serving based on roasting at 135°C for >45 min (i.e., saleable product process parameters). This study demonstrates that sunflower seeds roasted to saleable parameters should not represent a public health risk from potential presence of Salmonella.

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