REDUCING ESCHERICHIA COLI O157 RISK IN RURAL COMMUNITIES

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REDUCING ESCHERICHIA COLI O157 RISK IN RURAL
COMMUNITIES Dan Rigby, University of Manchester
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Infectivity of E. coli O157 in the environment

• The physiology of E. coli O157 in agricultural
  environments
• viable but non-culturable state?
• capability for re-infection?

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Infectivity of E. coli O157 in the environment
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Carriage and immunity

• Do individuals working with farm animals become
  immune and as a consequence have a very low
  perception of risk to the pathogen?

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Carriage and immunity

• Are workers engaged in handling livestock less
  susceptible to E. coli O157 infection than those
  who are not?
• Do workers engaged in handling livestock
  asymptomatically carry E. coli O157 and does this
  relate to strain genotype and phenotype?
• Do they develop immunity to pathogens as a result
  of low level prolonged exposure?

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Carriage and immunity

• Undertake a screening study of stools (qpathogen)
  and blood/saliva samples (qantibodies) from two
  sectors of the rural population.

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Risk assessment modelling

• Risk assessment models
• Risk reduction interventions

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Risk assessment modelling
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Grampian Study area
Arable Improved Grassland Wooded
Land Semi-natural vegetation Lochs Built up areas

• High incidence of O157 (10.1 cases per 100,000
  (2006),
• High cattle/sheep farming densities,

Aberdeen
Total Number of O157 Cases (1997-2006)
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Map Showing total numbers of cattle
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Map showing total numbers of sheep
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Map showing total numbers of E. coli O157
excreted per day
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Map showing number of people
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Private Water Supplies
Private water supplies in Aberdeenshire
Courtesy of Norval Strachan School of Biological
Sciences University of Aberdeen
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Water Supply Risk
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Risk assessment modelling

• Risk assessment models
• Risk reduction interventions

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Social Economic Research

• Risk Modelling
• The costs of illness
• Risk perceptions
• Risk reduction interventions

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The costs of illness

• Jenny Roberts LSHTM

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Interventions to Reduce Risk

• Many possible interventions
• Farm
• Abattoir etc
• Butchers
• Draw up candidate intervention sets and explore
  acceptability costs

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Example Farm Interventions

• Use of probiotics and prebiotics
• Using protective overcoats
• Keeping animals in cohorts, no new cattle
  introduced
• Keeping bedding dry
• Cleaning water tanks with chlorine monthly
• Using boot-dip
• No contact with other cattle (across fences,
  shows etc)

• Weekly emptying of water troughs
• Separate cattle and sheep grazing
• New stock quarantined for 1 week after purchasing
• 2 week gap between spreading waste and grazing
• 1 week gap between spreading waste and grazing

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Conjoint Methods
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Conjoint Best-Worst Scaling

• Animals in Cohorts Best
• Protective Overcoats Worst

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Best-Worst Scaling

• Animals in Cohorts Best
• Protective Overcoats Worst

Animals in Cohorts gt Protective Overcoats
Animals in Cohorts gt Bedding Dry Animals in
Cohorts gt 1 Week Grazing Gap Bedding Dry gt
Protective Overcoats 1 Week Grazing Gap gt
Protective Overcoats Bedding Dry -1 Week Grazing
Gap???
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Process

• Prioritising Candidate Interventions
• Investigate costs, effects acceptability

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Risk Perception Management

• Interviewed gt 2000 people
• Farmers, Residents, Visitors

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Risk Perception Management

• 53 taped interviews with people from
• Regulators/Statutory bodies
• Land Users
• Environment and tourism
• Food industry
• Media
• Education
• Consumers
• Researchers

• Does E. coli O157 matter, and if so how does it
  matter?
• What, if anything should be done?
• What is your role in managing O157 risk?
• What guides how you act to the risk of O157
• How is O157 risk communicated to and by you?
• What other diseases/risks are of concern to you?
• How do they rank compared with E. coli O157?

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REDUCING ESCHERICHIA COLI O157 RISK IN RURAL
COMMUNITIES http//www.abdn.ac.uk/reluecoliprojec
t/index.htm