Infection with Bonamia ostreae

What is Bonamia ostreae?

Bonamia ostreae is a protozoan that infects molluscs. Bonamia ostreae belongs to the phylum Haplosporidia.

What species of molluscs can be infected by Bonamia ostreae?

Each species of molluscs may have several common names, but only one common name is listed.

Species susceptible to Bonamia ostreae that exist in the natural environment in Canada include:

• Ostrea edulis (European flat oyster)

Species susceptible to Bonamia ostreae that do not exist in the natural environment in Canada include:

• Ostrea angasi (Southern flat oyster)
• Ostrea chilensis (Chilean flat oyster)
• Ostrea lutaria (New Zealand dredge oyster)
• Ostrea puelchana (Argentinean flat oyster)
• Ostrea denselamellosa* (Asiatic oyster*)
• Ostrea ariakensis* (Suminoe oyster*)

Note: Species identified with an asterisk have not been confirmed as susceptible to Bonamia ostreae.

Is Bonamia ostreae a risk to human health?

No. The causal agent of Bonamia ostreae is not a risk to human health.

What are the signs of Bonamia ostreae?

Bonamia ostreae causes disease in molluscs. It is a cause of mortality in juvenile and adult oysters.

• Oysters that are 2-4 years old and spawning are particularly affected
• Mortality can approach 100% in a group of oysters

Affected molluscs may exhibit any of the following signs:

• behaviour
  • gaping
• appearance
  • yellow discolouration of some internal organs (gills, mantle, digestive gland)
  • small mantle
  • fouling of shell margins

Is Bonamia ostreae found in Canada?

Yes. In Canada, Bonamia ostreae has been found in the marine environment of British Columbia.

How is Bonamia ostreae spread?

The complete life cycle of Bonamia ostreae is not known. Therefore, how infection is spread between oysters is unknown.

However, it is likely that people can spread Bonamia ostreae by moving infected molluscs and contaminated equipment.

How is Bonamia ostreae diagnosed?

Diagnosis of an infection with Bonamia ostreae requires laboratory testing. Not all infected molluscs show signs of disease.

How is Bonamia ostreae treated?

There are no treatment options currently available for Bonamia ostreae.

What measures can be taken to prevent the introduction and spread of Bonamia ostreae?

If you frequently handle or work with molluscs, be aware of the clinical signs of Bonamia ostreae.

Do not import live infected molluscs into Canada.

• An import permit is required from the Canadian Food Inspection Agency (CFIA) for certain species of molluscs as of December 2011.
• People bringing molluscs into Canada should check other federal, provincial, and/or territorial requirements before entering the country.

Do not introduce live molluscs from another country into the natural waters of Canada.

• People releasing molluscs into the natural waters or in rearing facilities within Canada should check if federal or provincial and/or territorial permits are required.

If you frequently handle or work with molluscs, be aware of where Bonamia ostreae occurs in your area.

• A federal, provincial and/or territorial permit or licence may be required to relocate molluscs within Canada.

Do not use molluscs that were bought in a grocery store as bait for catching fish or other aquatic animals.

Shells that are removed from molluscs or unwanted molluscs that you harvested or bought for your consumption should be disposed of in your municipal garbage.

The CFIA recommends that you do not visit Canadian aquaculture sites, zoos or aquariums for 14 days if you have travelled to another country and

• visited an aquaculture site, or
• had contact with wild molluscs.

Wash and disinfect the footwear you wore to the site or when you had contact with wild molluscs. Also wash your clothing thoroughly and dry it at a high temperature.

What is done to protect Canadian aquatic animals from Bonamia ostreae?

Bonamia ostreae is a reportable disease in Canada. This means that anyone who owns or works with aquatic animals, who knows of or suspects Bonamia ostreae in their molluscs, is required by law to notify the CFIA.

If Bonamia ostreae is found in Canada, the CFIA would control its spread by implementing disease response activities. These may include:

• controlling the movements of infected animals that people own or work with
• humanely destroying infected animals
• cleaning and disinfecting

The control measures chosen would depend on the situation.

What do I do if I think molluscs that I am raising or keeping have Bonamia ostreae?

If you suspect that molluscs you are raising or keeping may have Bonamia ostreae, you are required under the Health of Animals Act to immediately notify the CFIA of your suspicion.

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