Small distances can keep bacteria at bay for days
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Date
2014
Journal Title
Journal ISSN
Volume Title
Publisher
National Academy of Sciences
Abstract
Transmission of pathogens between spatially separated hosts, i.e.,
indirect transmission, is a commonly encountered phenomenon
important for epidemic pathogen spread. The routes of indirect
transmission often remain untraced, making it difficult to develop
control strategies. Here we used a tailor-made design to study
indirect transmission experimentally, using two different zoonotic
bacteria in broilers. Previous experiments using a single bacterial
species yielded a delay in the onset of transmission, which we
hypothesized to result from the interplay between diffusive motion
of infectious material and decay of infectivity in the environment.
Indeed, a mathematical model of diffusive pathogen
transfer predicts a delay in transmission that depends both on the
distance between hosts and on the magnitude of the pathogen
decay rate. Our experiments, carried out with two bacterial species
with very different decay rates in the environment, confirm the
difference in transmission delay predicted by the model. These
results imply that for control of an infectious agent, the time between
the distant exposure and the infection event is important.
To illustrate how this can work we analyzed data observed on the
spread of vancomycin-resistant Enterococcus in an intensive care
unit. Indeed, a delayed vancomycin-resistant Enterococcus transmission
component was identified in these data, and this component
disappeared in a study period in which the environment was thoroughly
cleaned. Therefore, we suggest that the impact of control
strategies against indirect transmission can be assessed using our
model by estimating the control measures’ effects on the diffusion
coefficient and the pathogen decay rate.
Description
Keywords
Diffusion model, Transmission experiment, Campylobacter jejuni, Escherichia coli
Citation
Van Bunnik, B. A., Ssematimba, A., Hagenaars, T. J., Nodelijk, G., Haverkate, M. R., Bonten, M. J., ... & De Jong, M. C. (2014). Small distances can keep bacteria at bay for days. Proceedings of the National Academy of Sciences, 111(9), 3556-3560. doi:10. 1073/pnas.1310043111/-/DCSupplemental.