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Bonamia sp. and Marteilia refringens in molluscs

The parasites M. refringens and Bonamia sp. are able to infect and cause disease in flat oysters and represent severe threats to wild and cultured flatoysters in Europe.  Additionally, the blue mussel may be carriers of M. refringens, although the parasite does not seem to cause disease in these mussels. 

Bonamia ostrea was detected in the Arendal area in 2008, but has not been detected since. Other Bonamia species or M. refringens have not been detected in Norway.


The Norwegian Veterinary Institute is not involved in the programme for 2015.

To document disease-free status for Norway of the parasites Bonamia sp. and Marteilia refringens.

Norway received disease-free status for Marteilia refringens and Bonamia sp. in 2004. Subsequent to the finding of B. ostreae in the Arendal area in 2008, a zone of protection and surveillance was declared and is still in force.

There has been no further detection of these parasites since 2008, and in 2013 the Norwegian Veterinary Institute adviced the Norwegian Food Safety Authority to take steps in order to reestablish disease-free status for B. ostrea in the Arendal area.