Genomic dissection of an Icelandic epidemic of respiratory disease in horses and associated zoonotic cases

S.R.H., J.P., and M.T.G.H. were supported by the Wellcome Trust (grant 098051). Iceland is free of the major infectious diseases of horses. However, in 2010 an epidemic of respiratory disease of unknown cause spread through the country's native horse population of 77,000. Microbiological invest...

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Bibliographic Details
Published in:mBio
Main Authors: Björnsdóttir, Sigríður, Harris, Simon R., Svansson, Vilhjálmur, Gunnarsson, Eggert, Sigurðardóttir, Ólöf G., Gammeljord, Kristina, Steward, Karen F., Newton, J. Richard, Robinson, Carl, Charbonneau, Amelia R. L., Parkhill, Julian, Holden, Matthew T. G., Waller, Andrew S.
Other Authors: University of St Andrews. School of Medicine, University of St Andrews. Infection Group, University of St Andrews. Infection and Global Health Division, University of St Andrews. Biomedical Sciences Research Complex
Format: Article in Journal/Newspaper
Language:English
Published: 2017
Subjects:
Icelandic horse
Streptococcus zooepedemicus
Epidemiology
Genome analysis
Respiratory pathogens
Zoonotic infections
QR Microbiology
QH301 Biology
QL Zoology
DAS
SDG 3 - Good Health and Well-being
QR
QH301
QL
Iceland
Online Access:http://hdl.handle.net/10023/11396
https://doi.org/10.1128/mBio.00826-17
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Summary:S.R.H., J.P., and M.T.G.H. were supported by the Wellcome Trust (grant 098051). Iceland is free of the major infectious diseases of horses. However, in 2010 an epidemic of respiratory disease of unknown cause spread through the country's native horse population of 77,000. Microbiological investigations ruled out known viral agents but identified the opportunistic pathogen Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) in diseased animals. We sequenced the genomes of 257 isolates of S. zooepidemicus to differentiate epidemic from endemic strains. We found that although multiple endemic clones of S. zooepidemicus were present, one particular clone, sequence type 209 (ST209), was likely to have been responsible for the epidemic. Concurrent with the epidemic, ST209 was also recovered from a human case of septicemia, highlighting the pathogenic potential of this strain. Epidemiological investigation revealed that the incursion of this strain into one training yard during February 2010 provided a nidus for the infection of multiple horses that then transmitted the strain to farms throughout Iceland. This study represents the first time that whole-genome sequencing has been used to investigate an epidemic on a national scale to identify the likely causative agent and the link to an associated zoonotic infection. Our data highlight the importance of national biosecurity to protect vulnerable populations of animals and also demonstrate the potential impact of S. zooepidemicus transmission to other animals, including humans. Publisher PDF Peer reviewed

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