Spread of E. coli O157 infection among Scottish cattle farms: Stochastic models and model selection

Zhang, Xu‐Sheng; Chase-Topping, Margo; McKendrick, Iain J.; Savill, Nicholas J.; Woolhouse, Mark

doi:10.1016/j.epidem.2010.02.001

Cited by 16 publications

(62 citation statements)

References 29 publications

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“…This indicates that larger herds have higher probability of becoming infected [9]. The mode of the recovery rate is about 0.025 (0.032) per day (therefore the average infectious period is about 40 (31) days), which is consistent with data from smaller scale longitudinal studies [22].…”

Section: Discussionsupporting

confidence: 63%

“…This implies that cattle movements alone are insufficient to maintain infection in this population [9,19]. Reducing movement-related transmission can, however, play a modest role in supplementing other interventions (figures 4 and 5).…”

Section: Discussionmentioning

confidence: 99%

“…[9]. Different model variants that describe different mechanisms of spread of the bacterium among Scottish cattle farms were examined based on the IPRAVE survey data [7].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

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Escherichia coliO157 infection on Scottish cattle farms: dynamics and control

Zhang

Woolhouse

2010

J. R. Soc. Interface.

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“…The odds of testing positive for fecal E. coli O157:H7 were 4.2 times higher for beef cattle on ranches that used surface water sources for drinking than for cattle on ranches without surface water access (odds ratio [OR], 4.2). Interestingly, a recent history of movement between pastures or rangeland locations was not significantly associated with fecal shedding of E. coli O157:H7 (Table 2), which is in contrast to related findings in Scotland where recent movement of cattle onto the farm was an identified risk factor for this pathogen (26,27,29). It is important to interpret these findings from the final logistic regression model as statistical associations, given those data were collected in a cross-sectional manner.…”

Section: Resultscontrasting

confidence: 51%

Prevalence and Genomic Characterization of Escherichia coli O157:H7 in Cow-Calf Herds throughout California

Worley

Flores

Yang

et al. 2017

Appl Environ Microbiol

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Escherichia coli serotype O157:H7 is a zoonotic food-and waterborne bacterial pathogen that causes a high hospitalization rate and can cause lifethreatening complications. Increasingly, E. coli O157:H7 infections appear to originate from fresh produce. Ruminants, such as cattle, are a prominent reservoir of E. coli O157:H7 in the United States. California is one of the most agriculturally productive regions in the world for fresh produce, beef, and milk. The close proximity of fresh produce and cattle presents food safety challenges on a uniquely large scale. We performed a survey of E. coli O157:H7 on 20 farms in California to observe the regional diversity and prevalence of E. coli O157:H7. Isolates were obtained from enrichment cultures of cow feces. Some farms were sampled on two dates. Genomes from isolates were sequenced to determine their relatedness and pathogenic potential. E. coli O157:H7 was isolated from approximately half of the farms. The point prevalence of E. coli O157:H7 on farms was highly variable, ranging from zero to nearly 90%. Within farms, generally one or a few lineages were found, even when the rate of isolation was high. On farms with high isolation rates, a single clonal lineage accounted for most of the isolates. Farms that were visited months after the first visit might have had the same lineages of E. coli O157:H7. Strains of E. coli O157:H7 may be persistent for months on farms.IMPORTANCE This survey of 20 cow-calf operations from different regions of California provides an in depth look at resident Escherichia coli O157:H7 populations at the molecular level. E. coli O157:H7 is found to have a highly variable prevalence, and with whole-genome sequencing, high prevalences in herds were found to be due to a single lineage shed from multiple cows. Few repeat lineages were found between farms in this area; therefore, we predict that E. coli O157:H7 has significant diversity in this area beyond what is detected in this survey. All isolates from this study were found to have pathogenic potential based on the presence of key virulence gene sequences. This represents a novel insight into pathogen diversity within a single subtype and will inform future attempts to survey regional pathogen populations.

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“…First to examine the risk factors for the presence of E. coli O157 on Scottish farms specifically testing hypotheses regarding local spread and the previous status of a farm. Previous research using data generated from survey 2 in this study failed to provide evidence of local spread [6]. However, the associations within that study were based on the spatial clustering of farms with no direct knowledge of the status of local farms in the area.…”

Section: Introductionmentioning

confidence: 82%

E. coli O157 on Scottish cattle farms: Evidence of local spread and persistence using repeat cross-sectional data

et al. 2014

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BackgroundEscherichia coli (E. coli) O157 is a virulent zoonotic strain of enterohaemorrhagic E. coli. In Scotland (1998-2008) the annual reported rate of human infection is 4.4 per 100,000 population which is consistently higher than other regions of the UK and abroad. Cattle are the primary reservoir. Thus understanding infection dynamics in cattle is paramount to reducing human infections.A large database was created for farms sampled in two cross-sectional surveys carried out in Scotland (1998 - 2004). A statistical model was generated to identify risk factors for the presence of E. coli O157 on farms. Specific hypotheses were tested regarding the presence of E. coli O157 on local farms and the farms previous status. Pulsed-field gel electrophoresis (PFGE) profiles were further examined to ascertain whether local spread or persistence of strains could be inferred.ResultsThe presence of an E. coli O157 positive local farm (average distance: 5.96km) in the Highlands, North East and South West, farm size and the number of cattle moved onto the farm 8 weeks prior to sampling were significant risk factors for the presence of E. coli O157 on farms. Previous status of a farm was not a significant predictor of current status (p = 0.398). Farms within the same sampling cluster were significantly more likely to be the same PFGE type (p < 0.001), implicating spread of strains between local farms. Isolates with identical PFGE types were observed to persist across the two surveys, including 3 that were identified on the same farm, suggesting an environmental reservoir. PFGE types that were persistent were more likely to have been observed in human clinical infections in Scotland (p < 0.001) from the same time frame.ConclusionsThe results of this study demonstrate the spread of E. coli O157 between local farms and highlight the potential link between persistent cattle strains and human clinical infections in Scotland. This novel insight into the epidemiology of Scottish E. coli O157 paves the way for future research into the mechanisms of transmission which should help with the design of control measures to reduce E. coli O157 from livestock-related sources.

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Spread of E. coli O157 infection among Scottish cattle farms: Stochastic models and model selection

Cited by 16 publications

References 29 publications

Escherichia coliO157 infection on Scottish cattle farms: dynamics and control

Escherichia coliO157 infection on Scottish cattle farms: dynamics and control

Prevalence and Genomic Characterization of Escherichia coli O157:H7 in Cow-Calf Herds throughout California

E. coli O157 on Scottish cattle farms: Evidence of local spread and persistence using repeat cross-sectional data

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