Guidance

Bonamia exitiosa

How to spot Bonamia exitiosa, what to do if you suspect it and measures to prevent its spread.

Applies to England and Wales

Documents

Details

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  1. How to spot Bonamia exitiosa
  2. How Bonamia exitiosa is spread
  3. Preventing and controlling Bonamia exitiosa
  4. Further information on Bonamia exitiosa
  5. Legislation relating to Bonamia exitiosaÌýÌý
  6. Who to contact if you suspect Bonamia exitiosa

Bonamia exitiosa is a protozoan parasite infecting several oyster species, in particular the native (or flat) oyster (Ostrea edulis).ÌýÌý

Information on susceptible and vector species can be found here: Susceptible and vector species - 51²è¹Ý (www.gov.uk)

Great Britain is free from Bonamia exitiosa, and it is a ‘listed’ (also referred to as ‘notifiable’) disease which you are legally obligated to report immediately to the Fish Health Inspectorate (FHI), Cefas. Fish Health Inspectorate - 51²è¹Ý (www.gov.uk)Ìý

In 2011 Bonamia exitiosa was detected in a sample of native oysters collected from a trader operating in Cornwall. The affected area was subject to controls and extensive surveillance and retesting, all subsequent samples were negative, and controls lifted in 2013. Since then, there have been no further outbreaks of Bonamia exitiosa in the UK.Ìý

It does not affect humans.Ìý

How to spot Bonamia exitiosaÌý

Signs of the disease can include:Ìý

  • Increase of dead / empty shellsÌý
  • Gaping shells which don’t close when touched or when exposed to airÌý
  • Gills can appear eroded.Ìý

How Bonamia exitiosa is spreadÌý

Bonamia exitiosa is spread through movements of and contact with infected shellfish and contact with contaminated equipment or water. Infected shellfish may release infective particles, spreading the parasite directly from host to host, and infected planktonic shellfish larvae may also contribute to the spread of the parasite.ÌýÌýÌý

Preventing and controlling Bonamia exitiosaÌýÌý

There is no treatment for Bonamia exitiosa.Ìý

Prevention is the best approach to disease control. You can protect your shellfish by being aware of the signs of Bonamia exitiosa and other serious diseases and checking stock health regularly. Implement good husbandry and biosecurity practises.Ìý

Further information on biosecurity measures plans, guidance and templates can be found here: Biosecurity Measure Plans - Information and Templates - 51²è¹Ý (www.gov.uk)Ìý

You must be sure any shellfish introduced are Bonamia exitiosa free. Do not buy shellfish of unknown origin. Follow the rules on moving aquatic animals: Aquatic animal health and movements guides - 51²è¹Ý (www.gov.uk)Ìý

You must report it to the FHI immediately if you notice or become aware of shellfish showing any of the signs of Bonamia exitiosa, particularly increased mortality and gaping shells. The FHI will investigate and if required apply disease control measures.ÌýÌýÌý

Further information on Bonamia exitiosaÌý

ÌýÌý

Legislation relating to Bonamia exitiosaÌý

2009ÌýÌý

The listed diseases are in and .Ìý

Who to contact if you suspect Bonamia exitiosaÌýÌý

If you suspect or know of a listed disease of fish and shellfish in England and Wales, you must report it immediately to the Fish Health Inspectorate (FHI), Cefas. You must also tell the FHI immediately if you know or suspect that increased mortality has occurred.ÌýÌý

Under the Aquatic Animal Health (England and Wales) Regulations 2009 it is a legal obligation to report suspicion of Bonamia exitiosa in any farmed or wild shellfish to the FHI. It is an offence under the Regulations to fail to inform the FHI of suspicion of Bonamia exitiosa.Ìý

  • ·¡³¾²¹¾±±ô: fhi@cefas.gov.ukÌý
  • Telephone: 01305 206700Ìý- Monday to Thursday - 9:00 am to 5:00 pm, Friday 9:00 am to 4:30 pmÌý
  • For emergencies out of hours telephone: 01305 206630Ìý

Fish Health InspectorateÌý
Centre for Environment, Fisheries and Aquaculture Science (Cefas)
Barrack Road,ÌýThe Nothe
Weymouth
Dorset
DT4 8UB

Updates to this page

Published 22 March 2024
Last updated 11 September 2024 show all updates
  1. Updated link to susceptible and vector species list.

  2. Vector and Susceptible species list updated from v1.1 to v1.2.

  3. Updated susceptible/vector species list.

  4. First published.

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