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