title: Predicting the public health benefit of vaccinating cattle against Escherichia coli O157.
abstract: Identifying the major sources of risk in disease transmission is key to designing effective controls. However, understanding of transmission dynamics across species boundaries is typically poor, making the design and evaluation of controls particularly challenging for zoonotic pathogens. One such global pathogen is Escherichia coli O157, which causes a serious and sometimes fatal gastrointestinal illness. Cattle are the main reservoir for E. coli O157, and vaccines for cattle now exist. However, adoption of vaccines is being delayed by conflicting responsibilities of veterinary and public health agencies, economic drivers, and because clinical trials cannot easily test interventions across species boundaries, lack of information on the public health benefits. Here, we examine transmission risk across the cattle-human species boundary and show three key results. First, supershedding of the pathogen by cattle is associated with the genetic marker stx2. Second, by quantifying the link between shedding density in cattle and human risk, we show that only the relatively rare supershedding events contribute significantly to human risk. Third, we show that this finding has profound consequences for the public health benefits of the cattle vaccine. A naïve evaluation based on efficacy in cattle would suggest a 50% reduction in risk; however, because the vaccine targets the major source of human risk, we predict a reduction in human cases of nearly 85%. By accounting for nonlinearities in transmission across the human-animal interface, we show that adoption of these vaccines by the livestock industry could prevent substantial numbers of human E. coli O157 cases.
authors.affiliation: Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, United Kingdom.
authors.forename: Louise
authors.initials: L
authors.lastname: Matthews
authors.forename: Richard
authors.initials: R
authors.lastname: Reeve
authors.forename: David L
authors.initials: DL
authors.lastname: Gally
authors.forename: J Chris
authors.initials: JC
authors.lastname: Low
authors.forename: Mark E J
authors.initials: ME
authors.lastname: Woolhouse
authors.forename: Sean P
authors.initials: SP
authors.lastname: McAteer
authors.forename: Mary E
authors.initials: ME
authors.lastname: Locking
authors.forename: Margo E
authors.initials: ME
authors.lastname: Chase-Topping
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Haydon
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Allison
authors.forename: Mary F
authors.initials: MF
authors.lastname: Hanson
authors.forename: George J
authors.initials: GJ
authors.lastname: Gunn
authors.forename: Stuart W J
authors.initials: SW
authors.lastname: Reid
mesh_terms: D000818:Animals; D057138:Bacterial Shedding / Q000235:genetics; D001428:Bacterial Vaccines / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology* / Q000517:prevention & control*; D004927:Escherichia coli Infections / Q000517:prevention & control / Q000635:transmission / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000472:pathogenicity*; D005243:Feces / Q000382:microbiology; D006801:Humans; D032541:Mass Vaccination / Q000662:veterinary*; D018448:Models, Immunological; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011634:Public Health; D018570:Risk Assessment; D012606:Scotland; D022641:Shiga Toxin 2 / Q000235:genetics / Q000378:metabolism; D015047:Zoonoses / Q000382:microbiology / Q000517:prevention & control*
chemical_list: D001428:Bacterial Vaccines; D022641:Shiga Toxin 2
keywords: 80–20 rule; cross-species transmission; one health; zoonoses
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