Infection with Pythium flevoense in a harbour porpoise (Phocoena phocoena) as a novel cause of dermatitis in marine mammals

Edwin J B Veldhuis Kroeze, Cornelis E van Elk, Marco W G van de Bildt, Peter R W A van Run, Geoffrey Foster, Nissrine Abou-Chakra, Rasmus Krøger Hare, Thijs Kuiken*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
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The oomycete Pythium flevoense was diagnosed as the cause of dermatitis in a young adult female harbour porpoise (Phocoena phocoena) that had been trapped in a pound net in a temperate saltwater environment. Disease from Pythium sp. infection-pythiosis-is infrequently diagnosed in humans, horses, dogs, cattle, and few other mammalian species. Pythiosis is typically associated with exposure to tropical or subtropical freshwater conditions, and typically caused by Pythium insidiosum. However, until now, pythiosis has been reported in neither marine mammals nor temperate saltwater conditions, and P. flevoense is not known as a cause of pythiosis in mammals. This porpoise developed generalised dermatitis despite treatment and euthanasia was necessary. Histopathological evaluation revealed a chronic active erosive dermatitis, with intralesional hyphae morphologically consistent with a Pythium sp. PCR analysis and sequencing of affected skin matched Pythium flevoense with a 100% similarity to the reference strain. Additional diagnostics excluded other pathogens. Based on this case report, P. flevoense needs to be considered as a mammalian pathogen. Furthermore, harbour porpoises and possibly other marine mammals may be at risk of infection with P. flevoense, and pythiosis should be included in the differential diagnosis of dermatitis in marine mammals.

Original languageEnglish
Article number102
JournalVeterinary Research
Publication statusPrint publication - 2 Nov 2023

Bibliographical note

© 2023. The Author(s).


  • Humans
  • Female
  • Horses
  • Animals
  • Dogs
  • Cattle
  • Phocoena
  • Pythiosis/diagnosis
  • Pythium
  • Dermatitis/veterinary
  • Cattle Diseases
  • Dog Diseases/diagnosis
  • Horse Diseases
  • Novel pathogen
  • oomycete
  • dermatitis
  • harbour porpoise
  • marine mammal
  • Pythium flevoense
  • cetacean


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