Ian Laing

Some oyster diseases

List of Diseases Bower, S.M. and McGladdery, S.E. (2003): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish URL:

The Single European Union Market Animal health conditions for placing aquaculture animals on the market ~ EC Directive 91/67, as amended.

Europa Animal Health and Welfare Web site

Listed diseases - THEN 95/70 Haplosploridium nelsoni Haplosploridium costale Perkinsus marinus Perkinsus olseni Mikrocytos mackini Mikrocytos roughleyi Oyster velar virus Marteilia sydneyi 91/67 Bonamia ostreae Marteilia refringens 2003/390 NON-Susceptible species Bonamia – Pacific oysters, mussels and clams Marteilia – Pacific oysters

OIE - International Organisation for Animal Health Aquatic Animal Code and Manual

2006/88 Susceptible species Diseases Flat oysters Cupped oysters Mussels Bonamia ostreaeYes Marteilia refringensYes Perkinsus marinusYes Bonamia exitiosaYes Microcytos mackiniYes Listed diseases - NOW

Aims of the legislation Prevent the spread of serious disease Allow trade This means Controlling the movement of shellfish Import and export checks

Bonamiasis Introduced into Europe in Brittany Bonamia ostreae is an intracellular plasmodial protozoan parasite (2-5  m) that belongs to the Haplosporidium group. It affects the granular blood cells (haemocytes) of flat oysters.

Bonamia ostreae Shellfish News Project BOLCI Web site – Google – 14,000 results ASFA – 168 papers

EU Health Rules (91/67/EEC) UK programmes approved (92/528/EEC) Approved Zones (2002/300/EC) Zones in Great Britain 1993 – infected areas Loch Sunart (E) and Milford Haven (F) 2007 – West Loch Tarbert (G) 2008 – North Kent

Meanwhile, in Ireland – Achill Sound and Blacksod Bay 2005 – Lough Foyle 2006 – Lough Swilly Strangford Lough

“Placing on the market” (2006/88 continued) Authorisation of Aquaculture Production Businesses includes dispatch and purification centres Susceptible and vector species Risk-based surveillance for increased mortality

Surveillance for mortality FishMolluscs MobileSedentary Visible behaviourStatic EndoskeletonShell ContainedOpen (sea bed)

Marteilia refringens Marteilia (type M) in mussels in Southampton Water (and elsewhere) One species? Two types?

Pacific oysters Oyster Herpes Virus Vibrio splendidus Environmental factors “Summer mortality” 500 μm

2006/88 Susceptible species Diseases White Spot DiseaseAll decapod crustaceans Taura SyndromeThree tropical shrimp spp Yellowhead diseaseSeven tropical shrimp spp Listed diseases - NEW

White spot disease (WSD) Global spread via live and frozen animal movements – 100% mortality in days – no effective treatment Can be transmitted to European decapods (crayfish, crabs, lobsters) Experimental infection of European lobster via feeding of WSD-infected prawns Causes disease within the European water temperature range Little research into vectors/carrier hosts

IS THERE A THREAT IN EUROPE? Small crustacean aquaculture industry Large and very valuable marine fishery for prawns, lobsters and crabs Potential routes of entry of WSD to Europe – larvae or broodstock for aquaculture, imported fresh and frozen prawns or live potentially carrier species for consumption Significant movement of fresh, frozen and live European crustaceans within the EU White spot disease (WSD)

I hope that was not too complicated Note: None of these diseases affect humans