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Environmental Factors Associated with the Carriage of Bacterial Pathogens in Norway Rats


Worldwide, Norway rats (Rattus norvegicus) carry a number of zoonotic pathogens. Many studies have identified rat-level risk factors for pathogen carriage. The objective of this study was to examine associations between abundance, microenvironmental and weather features and Clostridium difficile, antimicrobial-resistant (AMR) Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) carriage in urban rats. We assessed city blocks for rat abundance and 48 microenvironmental variables during a trap-removal study, then constructed 32 time-lagged temperature and precipitation variables and fitted multivariable logistic regression models. The odds of C. difficile positivity were significantly lower when mean maximum temperatures were high (≥ 12.89°C) approximately 3 months before rat capture. Alley pavement condition was significantly associated with AMR E. coli. Rats captured when precipitation was low (< 49.40 mm) in the 15 days before capture and those from blocks that contained food gardens and institutions had increased odds of testing positive for MRSA. Different factors were associated with each pathogen, which may reflect varying pathogen ecology including exposure and environmental survival. This study adds to the understanding of how the microenvironment and weather impacts the epidemiology and ecology of zoonotic pathogens in urban ecosystems, which may be useful for surveillance and control activities.

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We wish to thank Kirbee Parsons and Alice Feng for their assistance with environmental data and rat collection and Victoria Chang and Heather Anholt for their assistance with sample collection. We thank J. Scott Weese for pathogen testing and Kate Bishop-Williams for her insight into assessing time-lagged weather data. The fieldwork was made possible by the assistance of the City of Vancouver (Murray Wightman and Stuart McMillan), the Urban Health Research Initiative, the Vancouver Injection Drug Users Study and the Vancouver Area Network of Drug Users. J. Rothenburger’s research is supported by the following: Natural Sciences and Engineering Research Council Alexander Graham Bell Canada Graduate Scholarship-Doctoral, Canadian Federation of University Women Dr. Margaret McWilliams Pre-Doctoral Fellowship, Imperial Order Daughters of the Empire War Memorial Scholarship, Ontario Veterinary College Graduate Student Fellowship and the University of Guelph Dean’s Tri-Council Scholarship. The Canadian Institutes of Health Research funded this study (MOP– 119530).

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Correspondence to Jamie L. Rothenburger.

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All the authors declare that they have no conflict of interest.

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We followed all applicable institutional and/or national guidelines for the care and use of animals and the University of British Columbia Animal Care Committee (A11-0087) approved this study.

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Rothenburger, J.L., Himsworth, C.G., Nemeth, N.M. et al. Environmental Factors Associated with the Carriage of Bacterial Pathogens in Norway Rats. EcoHealth 15, 82–95 (2018).

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  • Disease ecology
  • Environment
  • Epidemiology
  • Norway rat
  • Rattus
  • Zoonotic