Effectiveness of simulated interventions in reducing the estimated prevalence of<i>E. coli</i>O157:H7 in lactating cows in dairy herds

Ahmadi, Bouda Vosough; Frankena, K.; Turner, Joanne; Velthuis, A.G.J.; Hogeveen, H.; Huirne, R.B.M.

doi:10.1051/vetres:2007029

Cited by 19 publications

(6 citation statements)

References 27 publications

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“…Mathematical models have been used to inform the design and impact of interventions [12][13][14], understand transmission dynamics in dairy [15,16] and beef [17,18] production systems, and determine the key processes that drive infection dynamics [16,19]. To date, much of the modelling has been carried out by constructing and simulating from mechanistic models [16] and, fitting these models to experimental infection data [20] or cross-sectional data on prevalence and concentration of E. coli O157:H7 in cattle faeces [19].…”

Section: Introductionmentioning

confidence: 99%

‘Super' or just ‘above average'? Supershedders and the transmission of Escherichia coli O157:H7 among feedlot cattle

Spencer

Besser

Cobbold

et al. 2015

J. R. Soc. Interface.

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Supershedders have been suggested to be major drivers of transmission of Escherichia coli O157:H7 (E. coli O157:H7) among cattle in feedlot environments, despite our relatively limited knowledge of the processes that govern periods of high shedding within an individual animal. In this study, we attempt a data-driven approach, estimating the key characteristics of high shedding behaviour, including effects on transmission to other animals, directly from a study of natural E. coli O157:H7 infection of cattle in a research feedlot, in order to develop an evidence-based definition of supershedding. In contrast to the hypothesized role of supershedders, we found that high shedding individuals only modestly increased the risk of transmission: individuals shedding over 10 3 cfu g 21 faeces were estimated to pose a risk of transmission only 2.45 times greater than those shedding below that level. The data suggested that shedding above 10 3 cfu g 21 faeces was the most appropriate definition of supershedding behaviour and under this definition supershedding was surprisingly common, with an estimated prevalence of 31.3% in colonized individuals. We found no evidence that environmental contamination by faeces of shedding cattle contributed to transmission over timescales longer than 3 days and preliminary evidence that higher stocking density increased the risk of transmission.

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Section: Introductionmentioning

confidence: 99%

‘Super' or just ‘above average'? Supershedders and the transmission of Escherichia coli O157:H7 among feedlot cattle

Spencer

Besser

Cobbold

et al. 2015

J. R. Soc. Interface.

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“…Based on these, we use simulations to examine the effectiveness of different modelled interventions. Measures such as vaccination [10], biosecurity or a combination of these [11,12] may be considered as options for controlling E. coli O157 infections in cattle. Several theoretical studies have investigated the expected impacts of such measures within a single herd [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…Measures such as vaccination [10], biosecurity or a combination of these [11,12] may be considered as options for controlling E. coli O157 infections in cattle. Several theoretical studies have investigated the expected impacts of such measures within a single herd [11][12][13][14]. These have provided useful information on how to deploy vaccination and improved biosecurity to reduce within-herd transmission, transmission from the wider environment and shedding rate and duration.…”

Section: Introductionmentioning

confidence: 99%

Escherichia coliO157 infection on Scottish cattle farms: dynamics and control

Zhang

Woolhouse

2010

J. R. Soc. Interface.

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In this study, we parametrize a stochastic individual-based model of the transmission dynamics of Escherichia coli O157 infection among Scottish cattle farms and use the model to predict the impacts of both targeted and non-targeted interventions. We first generate distributions of model parameter estimates using Markov chain Monte Carlo methods. Despite considerable uncertainty in parameter values, each set of parameter values within the 95th percentile range implies a fairly similar impact of interventions. Interventions that reduce the transmission coefficient and/or increase the recovery rate of infected farms (e.g. via vaccination and biosecurity) are much more effective in reducing the level of infection than reducing cattle movement rates, which improves effectiveness only when the overall control effort is small. Targeted interventions based on farm-level risk factors are more efficient than non-targeted interventions. Herd size is a major determinant of risk of infection, and our simulations confirmed that targeting interventions at farms with the largest herds is almost as effective as targeting based on overall risk. However, because of the striking characteristic that the infection force depends weakly on the number of infected farms, no interventions that are less than 100 per cent effective can eradicate E. coli O157 infection from Scottish cattle farms, implying that eliminating the disease is impractical.

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“…We evaluated the risk reduction impacts of generic interventions on density and prevalence in feces or on carcasses prior to evisceration. These levels of efficacy are likely achievable through one or more potential intervention protocols not included in the baseline model, including but not limited to feed additives, vaccination, and increased biosecurity at the on‐farm stage; and carcass rinses, steam pasteurization, and chilling at the beef processing stage . The reader is directed to several systematic reviews and meta‐analyses that have summarized the efficacy of these interventions to compare with the scenarios explored herein.…”

Section: Discussionmentioning

confidence: 99%

Multi‐Exposure Pathway Model to Compare Escherichia coli O157 Risks and Interventions

2017

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The relative contributions of exposure pathways associated with cattle-manure-borne Escherichia coli O157:H7 on public health have yet to be fully characterized. A stochastic, quantitative microbial risk assessment (QMRA) model was developed to describe a hypothetical cattle farm in order to compare the relative importance of five routes of exposure, including aquatic recreation downstream of the farm, consumption of contaminated ground beef processed with limited interventions, consumption of leafy greens, direct animal contact, and the recreational use of a cattle pasture. To accommodate diverse environmental and hydrological pathways, existing QMRAs were integrated with novel and simplistic climate and field-level submodels. The model indicated that direct animal contact presents the greatest risk of illness per exposure event during the high pathogen shedding period. However, when accounting for the frequency of exposure, using a high-risk exposure-receptor profile, consumption of ground beef was associated with the greatest risk of illness. Additionally, the model was used to evaluate the efficacy of hypothetical interventions affecting one or more exposure routes; concurrent evaluation of multiple routes allowed for the assessment of the combined effect of preharvest interventions across exposure pathways-which may have been previously underestimated-as well as the assessment of the effect of additional downstream interventions. This analysis represents a step towards a full evaluation of the risks associated with multiple exposure pathways; future incorporation of variability associated with environmental parameters and human behaviors would allow for a comprehensive assessment of the relative contribution of exposure pathways at the population level.

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Effectiveness of simulated interventions in reducing the estimated prevalence ofE. coliO157:H7 in lactating cows in dairy herds

Cited by 19 publications

References 27 publications

‘Super' or just ‘above average'? Supershedders and the transmission of Escherichia coli O157:H7 among feedlot cattle

‘Super' or just ‘above average'? Supershedders and the transmission of Escherichia coli O157:H7 among feedlot cattle

Escherichia coliO157 infection on Scottish cattle farms: dynamics and control

Multi‐Exposure Pathway Model to Compare Escherichia coli O157 Risks and Interventions

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