Post on 30-Jun-2020
Carp edema virus in Germany and differences in
susceptibility of common carp strains
- results from an epidemiological studies and
experimental infections.
Mikolaj Adamek1*, Max Helling1, Felix Teitge1, Verena Jung-Schroers1, David
Gela2, Veronika Piackova2, Martin Kocour2, Jerzy Adamek3, Dieter Steinhagen1
1Fish Disease Research Unit, Institute for Parasitology, University of Veterinary Medicine, Hannover, Germany
2Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, University of South Bohemia Ceske
Budejovice, Vodnany, Czech Republic 3Experimental Fish Farm in Zator, The Stanislaw Sakowicz Inland Fisheries Institute in Olsztyn, Poland
;
4th International Carp Conference 2017
Plan
What is carp edema virus?
Has CEV any significance in aquaculture?
Does CEV cause „Koi Sleepy Disease“?
Are there any differences in susceptibility of common carp strains to CEV?
What makes a fish sleep and die in „Koi Sleepy Disease”?
What are the recommendations?
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Koi sleepy disease / Carp edema virus
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CEV in common carp
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CEV in the world
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Japan 1976 (1974) USA 1997 (1996)
UK 2013 (1990`)
NL 2014
A 2015 (2014)
F 2015
CZ 2014
I 2014
PL 2016 (2013)
DE 2015 (2007)
HU 2017 (2016)
China 2017
India 2017
CEV genogroup I vs CEV genogroup IIa
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CEV genogroup IIa (Koi lineage)
CEV genogroup I (Carp lineage)
CEV genogroup IIb (mixed lineage)
KSD / CEV in Germany
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• Preliminary results from epidemiological studies
• 2007 - Archival samples (common carp)
• 2009 - Archival samples (Koi)
• 2009 - First detection in imported Koi
• 2014 - First disease outbreak in Koi
• 2015 - First disease outbreak in carp farm
Monthly distribution / Water temperature
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Clinical signs
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Clinical signs vs virus load
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Are other fish species involved?
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CEV experimental cohabitation
(i) Virus load and viral mRNA expression
(ii) Behavioural changes
(iii) Pathohistological changes
(iv) Mortality
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Is CEV infection causing „Koi Sleepy Disease”?
The target organ/tissue for CEV
The target organ/tissue for CEV replication is gill
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Differences in susceptibility of common carp strains to CEV
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Donor fish: common carp n=13 Recipient fish: Koi (Koi) Prerov scaly (PS) Ropsha (Rop) Amur wild carp (AS) (n=8/n=8/n=8/n=8) 10-12°C flow through 6d, 11d post exposure 4 fish per time point Gills
Cohabitation II (Genogroup I [Carp])
Donor fish: Koi n=3 Recipient fish: Koi (Koi) Prerov scaly (PS) Ropsha (Rop) Amur wild carp (AS) (n=8/n=8/n=8/n=8) 11-13°C flow through 6d, 11d post exposure 4 fish per time point Gills
Cohabitation IV (Genogroup IIa [Koi])
Differences in susceptibility of common carp strains to CEV
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DNA RNA
Genogroup I
Co II
Genogroup Iia
Co IV
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KSD (behavioural)
VS
Cohabitation
experiment
CEV genogroup Development of KSD (behavioural)
Carp strain
Koi PS Rop AS
Co II Genogroup I KSD KSD * -
Co IV Genogroup IIa KSD - - -
Cohabitation
experiment
CEV
genogroup
Observation
day
Development of KSD clinical signs (no. of fish)
Carp strain
Koi PS Rop AS
Co II Genogroup I 11 7/7 7/7 2/7 0/7
Co IV Genogroup IIa 11 4/4 0/4 0/4 0/4
Differences in the susceptibility of common carp strains to CEV
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Cohabitation
experiment
CEV
genogroup
Observation
day
Severity of histological changes
Carp stain
Koi PS Rop AS
Co II Genogroup I 11 +/++ ++/+++ ++ +/++
Co IV Genogroup IIa 11 +/++ +/++ +/++ ++
Cohabitation
experiment
CEV genogroup Development of KSD (gill histology)
Carp strain
Koi PS Rop AS
Co II Genogroup I mild / moderate moderate / severe moderate mild / moderate
Co IV Genogroup IIa mild / moderate mild / moderate mild / moderate moderate
KSD (gill histology)
CEV genogroup I is more virulent for
some strains of common carp
CEV genogroup IIa is more virulent
for Koi
Differences in the susceptibility of common carp strains to CEV
Genogroup IIa Genogroup I
Mortality
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Temp. 18 °C
n=10 (2-5 g)
Genogroup IIa Genogroup I *
Temp. 16 °C
n=5 (5-10 g)
*
Summary
• CEV is widely distributed in common carp aquaculture and was/is a cause for some idiopathic
disease outbreaks related to losses
• Significant differences in the virulence between CEV genogroups
• higher virulence towards the same fish group (common carp or koi) as the donor fish
• Amur wild carp are more resistant to an infection with CEV and do not develop clinical signs for
KSD
• Prerov scaly carp (in CEV genogroup I) and Koi carp (in CEV genogroup IIa)
developed high virus loads and clinical KSD
• Significant differences in virulence and genetics and strain separation (at least in Germany) of
CEV genogroups rise questions about a better separation of these viruses by nomenclature
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Recommendations
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We can recommend using resistant strains of carp (Amur wild carp) in
breeding programs which could limit potential losses caused by this
disease in aquaculture
Control your fish in the winter / spring time if they are apathetic / lying at
the bottom of the tank – do not blame it on NH3 intoxication – check them
for CEV (also in archival samples)
Keith Way Centre for Environment, Fisheries and Aquaculture
Science (CEFAS)
Acknowledgements
Faculty of Fisheries and Protection of Waters,
University of South Bohemia Ceske Budejovice,
Vodnany, Czech Republic
David Gela
Veronika Piackova
Martin Kocour
Fish Disease Research Unit,
University of Veterinary Medicine
Ilka Baumann
Max Helling
Felix Teitge
Verena Jung-Schroers
Dieter Steinhagen
Clinic for Swine and Small Ruminants,
University of Veterinary Medicine
Martin Ganter