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Isolation and characterisation of Vibrio cholerae from fish examined postmortem at ZSL London Zoo between 2014 and 2018
  1. Edmund J Flach1,
  2. Demi LeNette-Dawson1,
  3. David R Greig2,3,
  4. Amina Ismail Ahmed2,
  5. Claire Jenkins2,
  6. Shinto K John4,
  7. Shaheed K Macgregor1,
  8. Nic Masters1,
  9. Mark F Stidworthy5,
  10. Brian Zimmerman6 and
  11. Marie A Chattaway2
  1. 1 Wildlife Health Services, Zoological Society of London, London, UK
  2. 2 Gastrointestinal Bacteria Referral Unit, Public Health England Colindale, London, UK
  3. 3 Division of Infection and Immunity, The University of Edinburgh, The Roslin Institute and Royal (Dick) School of Veterinary Studies, Easter Bush, UK
  4. 4 Institute of Zoology, Zoological Society of London, London, UK
  5. 5 Pathology, International Zoo Veterinary Group, Keighley, UK
  6. 6 Zoological Services, Zoological Society of London, London, UK
  1. Correspondence to Edmund J Flach; edmund.flach{at}


Background When suspect Vibrio cholerae were cultured from fish at ZSL London Zoo, investigations were carried out to determine whether they were possible causes of cholera.

Methods Bacterial culture was carried out on fish examined postmortem and colonies were identified using standard techniques including the API 20NE biochemical test kits. Suspect isolates were submitted to the Public Health England laboratory for additional testing. Separately, a number of fish were submitted for routine histopathology.

Results On 13 occasions between 2014 and 2018, suspected V cholerae were cultured from individuals of eight different freshwater fish species. Archived cultures for eight of these (from six different fish species) were investigated and seven isolates (from five fish species) were confirmed as V cholerae, but all were non-O1, non-O139 strains. Whole-genome sequencing showed that the five fish species had unique V cholerae multilocus sequence types (three isolates from Aphanius danfordii were identical), all of which were genetically distant from human isolates.

Conclusions There was no evidence that these isolates could cause cholera. Histopathological changes consistent with vibriosis were seen in several fish, suggesting that V cholerae were causing the disease, but there were also concurrent infections or predisposing stress factors.

  • vibriosis
  • zoonoses
  • Vibrio cholerae
  • fish
  • aquatic organisms
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  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request. Original information on the cases described is obtainable from Wildlife Health Services, Zoological Society of London, Regents Park, London (

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