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26
July 2002 :
Vol 1 : No 3
CONTENTS
- KHV
may not be Herpesvirus after all
- Update: SVC in USA
- Aquarama '03 - A call for papers
- Editorial Comment
KHV MAY NOT BE HERPESVIRUS.
Recent studies in Israel may indicate that the virus that was the cause of mass mortalities in Koi and carp populations worldwide, may not be a Herpesvirus after all. It is now thought to be a large DNA viral particle under an electron microscope, mimics the Herpesvirus.
Since May 1998 several outbreaks of what has become known as Koi Herpesvirus (KHV) caused mass mortalities in private stocks and fish farms in the northwest of Israel, the mid-Atlantic region of the USA, and in different locations elsewhere in the world, resulting in enormous financial losses for those enterprises concerned. The most recent outbreak in mid-April in East Java, Indonesia caused losses estimated at 5 million USD. It will have a negative effect to the region's koi export industry no doubt.
In the May 2002 issue of OFI Journal, John Dawes provides an update on the status of the Koi viral disease in Israel and illuminates it with some of the latest research findings. The message is certainly that there is life after KHV, but more important, the virus may not be a Herpesvirus after all. This bodes well for the industry since the disease may not exhibit the fatal long term characteristics expected of a Herpesvirus.
To summarize the gist of the article: (sometimes verbatim, without permission)
The initial 1998 Israeli outbreak was followed by three others within 18 months; each on a different farm. Each of these outbreaks has been contained and overcome within a period of 12-18 months and the output of clean fish generally became possible 12-18 months after completion of the eradication programs.
The virus linked with the disease has been accepted as being a Herpesvirus (Hedrick et al, 2000) especially because transmission electron micrographs showed the viral particles exhibit the characteristic Herpesvirus shape when viewed in cross section at high magnitude.
However, recent research by Professor Moshe Kotler and colleagues at The Hebrew University and the team led by Dr. Izhak Bejerano at the Israeli Central Fish Health Laboratory, indicates that the virus may be a double-stranded DNA virus with icosahedron morphology that makes it resemble a Herpesvirus. (An icosahedron is a solid body with twenty plane faces, only a few of which can be seen in cross sectional view under transmission electron microscopic examination).
This may help explain the results of the various tests, experiments and field trials that have been carried out over the past few years. It may also mean that the periods of latency (dormancy) that are characteristic of Herpesviruses - such as those that cause cold sores in humans - may not apply to the Koi virus. This has significant implications for the rapid restoration of an infected Koi farm to good health. Logically, if the causative agent is not a Herpesvirus, the disease will require renaming, since the KHV label will no longer apply.
The researchers carried out numerous tests on what they termed NIF's (natural immune fish). The main conclusions derived from these tests are that:
a) NIF's do not infect fish which have never been exposed to the virus before, irrespective of whether these are newly-hatched fry, or fish at any other stage of maturity; and
b) NIF's do not appear to be carriers; and
c) NIF's do not appear to carry antibodies against the disease; and
d) NIF's do not appear to harbour any viral particles.
The results so far obtained do not constitute scientific proof and more research is needed, but their immunisation procedure by which NIF's are produced by exposure to sick fish, is showing positive results, which in turn supports the above.
Let us not be overly hasty in dropping the name KHV. Allow science to do its job and come up with a suggestion.
References
Dawes, J. Koi Viral Disease Update, OFI Journal, Issue 39: May 2002
Hedrick, R.P., Gilad, O., Yun, S., Spandenberg, J.V., Marty, G.D., Nordhausen, R.W., Kebus, M.J., Bercovier, H., Eldar, A. A Herpesvirus Associated with Mass Mortality of Juvenile and Adult Koi, a Strain of Common Carp. Journal of Aquatic Animal Health 12, 44-57, 2000.
Hutorau M., Smirnov, M., Benet, A., Magen, I., Bejerano, I., Rosen, A., Steinitz, M., Chen, N. and Kotler, M. Newly Emerging Disease of Cyprinus carpio is Caused by Large DNA Virus (in press).
(A much more extended, unverified list of references to koi viral diseases are available in the archived version of this newsletter for those with a scientific bias)
Ariav, R., Tinman, S., Paperna, I. and Bejerano, I.
First Report of Newly Emerging Viral Disease of Cyprinus
carpio Species in Israel. 9th International Conference on Diseases of Fish
and Shellfish. European Association of Fish Pathologists, 19-24, September 1999,
Rhodes, Greece.
Ariav, R. (1999) Fish health management and quality control programs in Israeli Koi (Cyprinus carpio) farms. Aquarama '99, Conference Abstracts, p51. (This talk reported on the extent on the viral disease)
Body A, Lieffrig F, Charlier C, Collard A (2000) Isolation of virus-like particles from koi (Cyprinus carpio) suffering gill necrosis. Bull Eur Assoc Fish Pathol 20:87-88
Bretzinger
A, Fischer-Scherl T, Oumouna M, Hoffman R, Truyen U (1999) Mass
mortalities in koi, Cyprinus carpio, associated with gill and skin disease. Bull
Eur Assoc Fish Pathol 19:182-185
Gilad O, Yun S, Andree KB, Adkison MA, Zlotkin A, Bercovier H, Eldar A, Hedrick RP (2002) Initial characteristics of koi herpesvirus and development of a polymerase chain reaction assay to detect the virus in koi, Cyprinus carpio koi. Dis Aquat Organ 2002 Mar 11; 48(2):101-8.
Hedrick RP, Groff JM, Okihiro MS, McDowell TS. (1990) Herpesviruses detected in papillomatous skin growths of koi carp (Cyprinus carpio). Journal of Wildlife Diseases, 26:578-581
Hedrick RP, Gilad O, Yun S, Spangenberg JV, Marty GD, Nordhausen RW, Kebus MJ, Bercovier H, Eldar A (2000) A herpesvirus associated with mass mortalityof juvenile and adult koi, a strain of a common carp. J Aquat Anim Health 12:44-57.
Hedrick
R.P. & Sano T. (1989) Herpesviruses of fishes. In Viruses of Lower
Vertebrates (eds W. Ahne & E. Kurstak),pp. 161-170. Springer-Verlag, Berlin.
Hedrick RP, Groff JM, Okihiro MS, McDowell TS. (1990) Herpesviruses detected in papillomatous skin growths of koi carp (Cyprinus carpio). Journal of Wildlife Diseases, 26:578-581.
Haimi, M. and Ariav, R. A Short Report on a Newly Emerging Viral Disease of Koi (Cyprinus carpio) and its Relevance to the Future Exportation of Coldwater Ornamental Fish from Israel. OFI Journal, Issue 30, 10-11, Feb. 2000.
Miyakazi, T., Okamoto, H., Kageyama, T. and Kobayashi,
T.Viremia-associated Ana- Aki-Byo, a New Viral Disease in Color Carp Cyprinus
carpio in Japan. Diseases of Aquatic Organisms, 39:3, 183-192,
2000.
Neukirch M, Bottcher K, Bunnajirakul S (1999)
Isolation of a virus from koi with altered gills. Bull Eur Assoc Fish Pathol
19:221-224
Oh, M-J., Jung, S-J., Choi, T-J., Kim, H-R., Rajendran, K.V., Kim, Y- J., Park, M-A. and Chun, S-K. A Viral Disease Occurring in Cultured Carp Cyprinus carpio in Korea. Fish Pathology 36 (3), 147-151, 2001.
Oyamatsu, T., Hata, N., Yamada, K., Sano, T., and Fukuda,
H. An Etiological Study on Mass Mortality of Cultured Color carp Juveniles
Showing Edema. Fish Pathology, 32:2, 81-88, 1997.
Sano, N., Moriwake, M., Hondo, R. and Sano, T. Herpesvirus cyprini:
a Search for Viral Genome in Infected Fish by in situ Hybridization. Journal
of Fish Diseases, 16:5, 495-499, 1993.
Sano, N., Sano, M., Sano, T. and Hondo, R. Herpesvirus cyprini: Detection of the Viral Genome by in situ Hybridization. Journal of Fish Diseases, 15:2, 153-162, 1992.
Sano, T., Morita, N., Shima, N. and Akimoto, M. A Preliminary Report on Pathogenicity and Oncogenicity of Cyprinid Herpesvirus. Bulletin of the European Association of Fish Pathologists. 10:1, 11-13, 1990.
Sano, T., Morita, N., Shima, N. and Akimoto, M. Herpesvirus cyprini: Lethality and Oncogenicity. Journal of Fish Diseases, 14:5, 533-543, 1991.
Tinman, S. and Benet Perelberg, A. (2001) Effect of Immunosuppression Treatment on Viral Disease Resistant (Survivors) Carp. Annual Report of the Research Stations, Fisheries Department, Israel Agriculture Ministry.
Yoshimizu, M. and Kimura, T. (1990) Viral Infections of Cultured Fishes in Japan. Second Asian Fisheries Forum - 17-22 April 1989, 959- 962. (Hirano, R. and Hanyu, I., - eds.)
UPDATE: SVC IN THE USA
Below the latest information from the OIE website concerning the SVC outbreak in the the US.
SPRING
VIRAEMIA OF CARP IN THE UNITED STATES OF AMERICA
(Disease never reported before).
Emergency report
Information received on 11 July 2002 from Dr Peter Fernandez, Associate Deputy
Administrator, International Services, United States Department of Agriculture
(USDA), Washington, DC:
Report date: 11 July 2002.
Nature of diagnosis: laboratory.
Date of initial detection of animal health incident: 24 April 2002.
Outbreaks:
Location No. of outbreaks
Kernersville, State of North Carolina 1 hatchery complex comprising 6 farms
Description of affected population: koi carp (Cyprinus carpio).
Total number of animals in the outbreak*:
Susceptible: 150 000; deaths: 15 000; destroyed: 135 000
* The figures refer to the fish population of the two farms that were affected
out of a total of six farms in the complex.
Diagnosis:
A. Laboratories where diagnosis was made:
- The disease was diagnosed on 24 April 2002 at the University of Arkansas Diagnostic Laboratory at Pine Bluff, State of Arkansas.
-
Diagnosis was confirmed on 5 July 2002 by the Centre for Environment, Fisheries,
and Aquaculture Science (CEFAS), Weymouth Laboratory, United Kingdom (OIE
Reference Laboratory for spring viraemia of carp).
B. Diagnostic tests used: tissue culture, immunocytochemistry.
C. Causal agent: spring viraemia of carp virus (rhabdovirus).
Epidemiology:
A. Source of agent / origin of infection: the source of infection has not yet
been identified.
B. Other epidemiological details: the possibility of tracing the source of the
virus is very limited. The establishment ships and receives fish on a weekly
basis. The hatchery is located adjacent to a river and river water is used on
the premises.
Control measures:
- As a result of the detection, 135,000 koi carp were destroyed at the hatchery.
- All six farms in the hatchery complex are under quarantine.
- The control plan is to depopulate and disinfect the tanks in the holding
facility. A disinfection, decontamination, and testing protocol for spring
viraemia of carp virus will be used to identify and maintain disease-free ponds
and fish.
- Fish and Wildlife authorities will be notified because this disease can affect
common carp.
AQUARAMA '03 - A CALL FOR PAPERS
The next Aquarama Conference will be held in Singapore between 29 May and 1 June 2003 has issued a call for papers..
Billed as the 3rd World Conference on Ornamental Fish Aquaculture, this meeting of leading industry and aquaculture experts is attracting keen interest worldwide. The two previous and highly successful stagings of what has already become a highly prestigious event in the aquatic calendar, have combined the latest scientific findings with the hottest - and often most controversial - topics affecting the international ornamental aquatic industry.
For information about your submission contact Julian Lim at julian-lim@cmpasia.com.sg or visit their site at www.aquarama.com.sg for further details.
EDITORIAL
COMMENT
It would seem that the issue of the first appearance of the virus is still not settled. The current epidemic was first witnessed in Israel in May 1998 and is still in full flight migrating across the world. It is insisted by some that the virus was previously detected elsewhere, notably Japan. While there is a large body of evidence pointing to various localised outbreaks of an infectious diseases with high mortality, reports of viral diseases are really much more rare. (really?)
The outbreak in Japan in 1989, reported on by Yoshimizu and Kimura, was identified in follow-up work by Sano, Hedrick and others as Herpesvirus cyprini. Dr RP Hedrick is confidant to insist that the 1998 outbreak of KHV was different to the Herpesvirus cyprini he, Sano and others reported on in the 90's. Still others would like to draw a parallel in the symptoms.
Does it matter? Wherever man has cultured things intensively, disease has been a constant threat.
We farmers like to blame others for a disease in our dams. It is nice to say it came from elsewhere while we only have ourselves to blame when things get out of hand. High stocking densities, poor health control and lack of quarantine measures are all essential elements of a disaster in the making.
But perhaps we should take it a step further. Once koi farming grows to become a local industry and a national asset, the authorities should step in with regulations to minimise the risk of health hazards and protect farmers from themselves.
No one likes regulations, but the damage done to the international koi trade due to bad press and buyer pessimism, is enormous.
Totsiens
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OUR MISSION: This free Newsletter is intended to share information of interest to the Breeders, Exporters, Importers and Dealers of Koi internationally. It is not intended for the average hobbyist. Your feedback or criticism of whatever kind will be valued. If you want to update me on whatever is happening in your part of the world, I will be delighted. The idea is to serve the Koi industry and keep commercial content out. If I make mistakes, well, correct me if you can substantiate your claim. Please forward this to anyone you think might be interested in our subject matter.
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