Modeling the die-off of E. coli and Ascaris in wastewater-irrigated vegetables: implications for microbial health risk reduction associated with irrigation cessation

2013 ◽  
Vol 68 (5) ◽  
pp. 1013-1021 ◽  
Author(s):  
Razak Seidu ◽  
Ingrid Sjølander ◽  
Amina Abubakari ◽  
Dennis Amoah ◽  
John A. Larbi ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Health Risk ◽  
Risk Reduction ◽  
Order Kinetic ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Biphasic Model ◽  
E Coli ◽  
Health Risk Reduction ◽  
Log Linear

This study assessed the die-off of Escherichia coli (E. coli) and Ascaris suum on lettuce (Great Lakes 118) and cabbage (Brassica oleracea var capitata) in wastewater-irrigated fields using comparative mathematical die-off models. The study revealed that none of the survival curves of E. coli and A. suum was best fitted with the log-linear model, indicating that the classical first-order kinetic approach is inadequate in many cases. The biphasic die-off model best described the die-off of E. coli on lettuce (kmax1 = 2.62 day−1 and kmax2 = 0.22 day−1) and cabbage (kmax1 = 1.06 day−1 and kmax2 = 0.53 day−1). The die-off of A. suum on lettuce was best described by the biphasic model (kmax1 = 0.48 day−1 and kmax2 = 0.01 day−1) and best described by log linear + tail (kmax = 0.44) on cabbage. A comparative health risk assessment associated with the consumption of lettuce showed significant underestimation of the number of days of irrigation cessation required to achieve E. coli O157:H7 and Ascaris tolerable annual infection risk when using biphasic die-off rates compared with other die-off rates. The study stresses the need to test different die-off models as inputs for quantitative microbial risk assessment (QMRA) particularly for interventions associated with health risk reduction.

scholarly journals Health-risk assessment for roof-harvested rainwater via QMRA in Ikorodu area, Lagos, Nigeria

2021 ◽  
Author(s):  
Chukwuemeka Kingsley John ◽  
Jaan H. Pu ◽  
Rodrigo Moruzzi ◽  
Manish Pandey
Keyword(s):  
Risk Assessment ◽  
Health Risk ◽  
Rainwater Harvesting ◽  
Treatment Technique ◽  
Quantitative Microbial Risk Assessment ◽  
Household Water Treatment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
E Coli ◽  
Risk Of Exposure

Abstract This paper presents a study to assess the roof-harvested rainwater (RHRW) in the Ikorodu area of Lagos state, Nigeria, and recommends guidance to minimise the health risk for its households. The types, design and use of rainwater harvesting systems have been evaluated in the study area to inspect the human risk of exposure to Escherichia coli (E. coli). To achieve these objectives, a detailed survey involving 125 households has been conducted which showed that 25% of them drink RHRW. Quantitative microbial risk assessment (QMRA) analysis has been used to quantify the risk of exposure to harmful E. coli from RHRW utilised as potable water, based on the ingestion of 2 L of rainwater per day per capita. Results have revealed that the maximum E. coli exposure risk from the consumption of RHRW, without application of any household water treatment technique (HHTTs) and with application of alum only, were 100 and 96 respectively, for the estimated number of infection risk per 10,000 exposed households per year. This estimation has been done based on 7% of E. coli as viable and harmful. Conclusively, it is necessary that a form of disinfectant be applied to the RHRW before use.

scholarly journals Quantitative Microbial Risk Assessment for Workers Exposed to Bioaerosol in Wastewater Treatment Plants Aimed at the Choice and Setup of Safety Measures

2018 ◽  
Vol 15 (7) ◽  
pp. 1490 ◽  
Author(s):  
Annalaura Carducci ◽  
Gabriele Donzelli ◽  
Lorenzo Cioni ◽  
Ileana Federigi ◽  
Roberto Lombardi ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Sensitivity Analysis ◽  
Wastewater Treatment ◽  
Health Risk ◽  
Average Risk ◽  
Quantitative Microbial Risk Assessment ◽  
Exposure Limits ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
The Impact

Biological risk assessment in occupational settings currently is based on either qualitative or semiquantitative analysis. In this study, a quantitative microbial risk assessment (QMRA) has been applied to estimate the human adenovirus (HAdV) health risk due to bioaerosol exposure in a wastewater treatment plant (WWTP). A stochastic QMRA model was developed considering HAdV as the index pathogen, using its concentrations in different areas and published dose–response relationship for inhalation. A sensitivity analysis was employed to examine the impact of input parameters on health risk. The QMRA estimated a higher average risk in sewage influent and biological oxidation tanks (15.64% and 12.73% for an exposure of 3 min). Sensitivity analysis indicated HAdV concentration as a predominant factor in the estimated risk. QMRA results were used to calculate the exposure limits considering four different risk levels (one illness case per 100, 1.000, 10.000, and 100.000 workers): for 3 min exposures, we obtained 565, 170, 54, and 6 GC/m3 of HAdV. We also calculated the maximum time of exposure for each level for different areas. Our findings can be useful to better define the effectiveness of control measures, which would thus reduce the virus concentration or the exposure time.

Quantitative Microbial Risk Assessment for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in Leafy Green Vegetables Consumed at Salad Bars

2010 ◽  
Vol 73 (2) ◽  
pp. 274-285 ◽  
Author(s):  
E. FRANZ ◽  
S. O. TROMP ◽  
H. RIJGERSBERG ◽  
H. J. van der FELS-KLERX
Keyword(s):  
Public Health ◽  
Escherichia Coli ◽  
Risk Assessment ◽  
Monte Carlo ◽  
Escherichia Coli O157 ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
The Public ◽  
E Coli

Fresh vegetables are increasingly recognized as a source of foodborne outbreaks in many parts of the world. The purpose of this study was to conduct a quantitative microbial risk assessment for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes infection from consumption of leafy green vegetables in salad from salad bars in The Netherlands. Pathogen growth was modeled in Aladin (Agro Logistics Analysis and Design Instrument) using time-temperature profiles in the chilled supply chain and one particular restaurant with a salad bar. A second-order Monte Carlo risk assessment model was constructed (using @Risk) to estimate the public health effects. The temperature in the studied cold chain was well controlled below 5°C. Growth of E. coli O157:H7 and Salmonella was minimal (17 and 15%, respectively). Growth of L. monocytogenes was considerably greater (194%). Based on first-order Monte Carlo simulations, the average number of cases per year in The Netherlands associated the consumption leafy greens in salads from salad bars was 166, 187, and 0.3 for E. coli O157:H7, Salmonella, and L. monocytogenes, respectively. The ranges of the average number of annual cases as estimated by second-order Monte Carlo simulation (with prevalence and number of visitors as uncertain variables) were 42 to 551 for E. coli O157:H7, 81 to 281 for Salmonella, and 0.1 to 0.9 for L. monocytogenes. This study included an integration of modeling pathogen growth in the supply chain of fresh leafy vegetables destined for restaurant salad bars using software designed to model and design logistics and modeling the public health effects using probabilistic risk assessment software.

Quantitative Assessment of the Microbial Risk of Leafy Greens from Farm to Consumption: Preliminary Framework, Data, and Risk Estimates

2011 ◽  
Vol 74 (5) ◽  
pp. 700-708 ◽  
Author(s):  
MICHELLE D. DANYLUK ◽  
DONALD W. SCHAFFNER
Keyword(s):  
Risk Assessment ◽  
Risk Model ◽  
Assessment Model ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
E Coli ◽  
Leafy Greens ◽  
Risk Estimates ◽  
Washing Process

This project was undertaken to relate what is known about the behavior of Escherichia coli O157:H7 under laboratory conditions and integrate this information to what is known regarding the 2006 E. coli O157:H7 spinach outbreak in the context of a quantitative microbial risk assessment. The risk model explicitly assumes that all contamination arises from exposure in the field. Extracted data, models, and user inputs were entered into an Excel spreadsheet, and the modeling software @RISK was used to perform Monte Carlo simulations. The model predicts that cut leafy greens that are temperature abused will support the growth of E. coli O157:H7, and populations of the organism may increase by as much a 1 log CFU/day under optimal temperature conditions. When the risk model used a starting level of −1 log CFU/g, with 0.1% of incoming servings contaminated, the predicted numbers of cells per serving were within the range of best available estimates of pathogen levels during the outbreak. The model predicts that levels in the field of −1 log CFU/g and 0.1% prevalence could have resulted in an outbreak approximately the size of the 2006 E. coli O157:H7 outbreak. This quantitative microbial risk assessment model represents a preliminary framework that identifies available data and provides initial risk estimates for pathogenic E. coli in leafy greens. Data gaps include retail storage times, correlations between storage time and temperature, determining the importance of E. coli O157:H7 in leafy greens lag time models, and validation of the importance of cross-contamination during the washing process.

scholarly journals Quantitative microbial risk assessment related to urban wastewater and lagoon water reuse in Abidjan, Côte d'Ivoire

2013 ◽  
Vol 12 (2) ◽  
pp. 301-309 ◽  
Author(s):  
R. I. Yapo ◽  
B. Koné ◽  
B. Bonfoh ◽  
G. Cissé ◽  
J. Zinsstag ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Cote D'ivoire ◽  
Côte D’Ivoire ◽  
Quantitative Microbial Risk Assessment ◽  
Urban Wastewater ◽  
Cote D’Ivoire ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
E Coli ◽  
Lagoon Water

We assessed the infection risks related to the use of wastewater in Abidjan, Côte d'Ivoire, by using quantitative microbial risk assessment (QMRA). Giardia lamblia and Escherichia coli were isolated and identified in wastewater samples from the canal and lagoon. The exposure assessment was conducted using a cross-sectional survey by questionnaire with 150 individuals who were in contact with the wastewater during their daily activities of swimming, fishing, washing, and collecting materials for reuse. Risk was characterised using the Monte Carlo simulation with 10,000 iterations. Results showed high contamination of water by G. lamblia and E. coli (12.8 CFU/100 mL to 2.97 × 104CFU/100 mL and from 0 cyst/L to 18.5 cysts/L, respectively). Estimates of yearly average infection risks for E. coli (90.07–99.90%, assuming that 8% of E. coli were E. coli O157:H7) and G. lamblia (9.4–34.78%) were much higher than the acceptable risk (10−4). These results suggest the need for wastewater treatment plants, raising awareness in the population in contact with urban wastewater and lagoon water. Our study also showed that QMRA is appropriate to study health risks in settings with limited data and budget resources.

Microbiological Risk from Minimally Processed Packaged Salads in the Dutch Food Chain

2014 ◽  
Vol 77 (3) ◽  
pp. 395-403 ◽  
Author(s):  
ANNEMARIE PIELAAT ◽  
FRANS M. van LEUSDEN ◽  
LUCAS M. WIJNANDS
Keyword(s):  
Risk Assessment ◽  
Quantitative Microbial Risk Assessment ◽  
Concentration Data ◽  
Production Chain ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
E Coli ◽  
Human Illness ◽  
Campylobacter Spp ◽  
Microbiological Surveillance

The objective of this study was to evaluate the microbial hazard associated with the consumption of mixed salads produced under standard conditions. The presence of Salmonella, Campylobacter spp., and Escherichia coli O157 in the Dutch production chain of mixed salads was determined. Microbial prevalence and concentration data from a microbiological surveillance study were used as inputs for the quantitative microbial risk assessment. Chain logistics, production figures, and consumption patterns were combined with the survey data for the risk assessment chain approach. The results of the sample analysis were used to track events from contamination through human illness. Wide 95% confidence intervals around the mean were found for estimated annual numbers of illnesses resulting from the consumption of mixed salads contaminated with Salmonella Typhimurium DT104 (0 to 10,300 cases), Campylobacter spp. (0 to 92,000 cases), or E. coli (0 to 800 cases). The main sources of uncertainty are the lack of decontamination data (i.e., produce washing during processing) and an appropriate dose-response relationship.

Sign in / Sign up

Export Citation Format

Share Document