Disease caused by Haplosporidium nelsoni

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Haplosporidium nelsoni causes multinuclear sphere X (MSX) disease in cultured and wild American oysters.

In Canada, Haplosporidium nelsoni is a federally reportable disease. This means that anyone who owns or works with aquatic animals, who knows of or suspects Haplosporidium nelsoni disease in the animals that they own or work with, is required by law to notify the CFIA.

Additional information

How do I get more information?

For more information about reportable diseases, visit the Aquatic Animal Health page, contact your local CFIA Animal Health Office, or your CFIA Area office:

  • Atlantic: 506-777-3939
  • Quebec: 514-283-8888
  • Ontario: 226-217-8555
  • West: 587-230-2200
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