Recent Mass Mortality Events

Affecting Pacific Oysters in Europe

Mike Gubbins

Fish health Inspectorate

Cefas

Weymouth

Officially Reported* Mortalities in France

During 2008

Bacteriology

Vibrio aestuarianus

V. Splendidus

V. harveyii

Virology

OsHV in

many

samples

Histology

No listed disease

* IFREMER 2009, WAHID (OIE) 2008, 2009

Officially Reported Mortalities in France

During 2008

Bacteriology

Vibrio aestuarianus

V. Splendidus

* IFREMER 2009, WAHID (OIE) 2008, 2009

Officially Reported Mortalities in France

During 2008

Bacteriology

Vibrio harveyii

* IFREMER 2009, WAHID (OIE) 2008, 2009

Officially Reported Mortalities in France

During 2008

Virology

OsHV-1

* IFREMER 2009, WAHID (OIE) 2008, 2009

Identification of OsHV-1 in 2008

OsHV-1 µvar

OsHV-1

Both

* IFREMER 2009, WAHID (OIE) 2008, 2009

Identification of OsHV-1 in 2008

OsHV-1 µvar

OsHV-1

Both

* IFREMER 2009, WAHID (OIE) 2008, 2009

Control Measures

• No movement control inside the

country in 2008

• Surveillance outside

containment and/or buffer zone

• Surveillance within containment

and/or buffer zone

• No treatments

Spread of Mortality

• Greater than usual mortalities appear to

be linked to shellfish introductions

• Evidence of spread to naive stock in

same areas

Increased Mortality in Republic of

Ireland 2008

Marine Institute data

• 3 reports of abnormal

mortality investigated in

August

• OsHV-1 identified in all

3 areas

• Seed imports in March

– June, but majority

from May – June.

Historical Perspective on OsHV-1

• First indication of herpesvirus in oysters

in1972

• 1991 associated with high mortality in

hatchery reared larval gigas in France

• 1993 associated with spat at some sites

• Replication / identification of virus in other

species

Historical Perspective on OsHV-1

• Found world wide

• Often, but not always, associated with

“summer mortality”

An Emerging Biotype of OsHV-1?

Data from J. F. Pepin, Ifremer 2009

• 2008 - 42% new biotype

• 2009 - 100% new biotype

• OsHV-1 µvar in the past?

• 38 batches of oysters tested from

previous OsHV-1, from USA, Japan,

China, France

An Emerging Biotype of OsHV-1?

Data from J. F. Pepin, Ifremer 2009

• 2008 - 42% new biotype

• 2009 - 100% new biotype

• OsHV-1 µvar in the past?

• 38 batches of oysters tested from

previous OsHV-1, from USA, Japan,

China, France

• None of these samples displayed the

identical profile to the new biotype

OsHV-1 µvar

Sequence differences between the µVar OsHV(PM09162)and OsHV-1 in the C2/C6

region

PM09162 AAAAGTTG GGATAATGAT TTTAGAATAG ATGTGATGTG CGGCAAGATG AATGGCAAGA TACACAATGA

OsHV-1 ........ .......... .......... .......... .......... .......... ..........

PM09162 GCTATTACCC GACCACAAAC CTAACGTTGT ATTCGATTAC GGATTAAGAA AATGGGTTCC ACAATCTAAA

OsHV-1 ......G... .......... .......... .......... .......... .......... ..........

PM09162 ATTAAAAAC- CCACATGGGG GCCAAGGAAT TTAAAGCCCC GGGGAAAAAA GTATAAATAG GCGCGATTTG

OsHV-1 ........AA .......... .......... .....--... C...G..... .......... ..........

PM09162 TCAGTTTAGA ATCATACCCA CAC--TCAAT CTCGAGTATA CCACAACTGC TAAATTAACA GCATCTACTA

OsHV-1 .......... .......... ...AC..... .......... .......... .......... ..........

PM09162 CTACTACTG- ---------- --AAAAATGC AGCCTTTCAC AGAATTTTGC ACCTTGACCA AAGCCATCAC

OsHV-1 ........AC TACTACTACT GA........ .......... .......... .......... ..........

PM09162 ATCAGCCAGC AACGACTTTT TCATCAACCA GACGAGGTTA ACATGCGACA TTTGTAAAGA GCTCGTCTCT

OsHV-1 .......... .......... .......... .......... .......... .......... ..........

PM09162 TTCAATTGCA AAGATAAAGT CGTGGCATCA TTGGCTGCAG TCAGATCTGA CATACCCATA GAAGTCACGG

OsHV-1 ...G.....G .......... .......... .......... .......... .......... ..........

PM09162 AACGCAAAGA CCTGAACCTC CTCGAC

OsHV-1 .......... .......... ......

2009

Officially Reported* Mortalities in France

During 2009

Reported in May

* IFREMER 2010, WAHID (OIE) 2009

Officially Reported* Mortalities in France

During 2009

Reported in May

Reported in June

* IFREMER 2010, WAHID (OIE) 2009

Officially Reported* Mortalities in France

During 2009

* IFREMER 2010, WAHID (OIE) 2009

OsHV-1 µvar

Identification of OsHV-1 in 2008

OsHV-1 µvar

OsHV-1

Both

* IFREMER 2009, WAHID (OIE) 2008, 2009

Control Measures

• Controls limited to juveniles from affected

areas?

• Only whilst mortality event causes more

than 15% loss?

• Adult oysters allowed from all areas?

• No notifiable diseases found

Spread of Mortality

• Greater than usual mortalities appear to

be linked to shellfish introductions

• Evidence of spread to naive stock in

same areas

Key

Purification

Relaying

2009

movements for farming/purification

Increased Mortality in the Republic

of Ireland in 2009

• 35 samples from 17 sites

• 31 positive for OsHV-1

• All OsHV-1 µvar

• All positive sites had received

shellfish from France

• Sites that did not receive

French stock were all negative

for OsHV-1Marine Institute data

Increased Mortality in Jersey

Started in June

Affected only Pacific oysters

Up to 68% mortality

Several areas affected

Re-occurred in September

Stock originated from France

Epidemiology reported by Ashley Pinel at

Jersey State Veterinary dept.

Disease Investigation

• Samples from Jersey (mortality event)

• Vibrios found – of significance?

• PCR positive for OsHV in all groups

• When sequenced = OsHV-1 µvar

Initial Survey of England and Wales

• High risk sites sampled

• 3 Mortality events

investigated

• No evidence for OsHV-1

Introduction of Community

Measures

?

Introduction of Community

Measures

Introduction of Community

Measures

2010?Official reports

So far (May) 2 official reports

Monitoring Programmes

1

2

43

1 Larne Lough

2 Strangford Lough

3 Dundrum Bay

4 Killough Bay

Crassostrea gigas Site Oyster herpesvirus surveillance 2010