Published Date: 2011-03-26 12:00:09
Subject: PRO/AH/EDR> Epizootic ulcerative synd., fish - Canada
Archive Number: 20110326.0952
EPIZOOTIC ULCERATIVE SYNDROME, FISH - CANADA
********************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>
Date: 25 Mar 2011
Source: OIE [edited]
<http://web.oie.int/wahis/public.php?page=single_report&pop=1&reportid=10381>
Epizootic ulcerative syndrome, Canada
-------------------------------------
Summary
Report type Immediate notification (Final report)
Start date 25 Sep 2010
Date of 1st confirmation of the event 28 Feb 2011
Report date 25 Mar 2011
Date submitted to OIE 25 Mar 2011
Date event resolved 02 Nov 2010
Reason for notification 1st occurrence of a listed disease
Manifestation of disease Clinical disease
Causal agent Aphanomyces invadans
Nature of diagnosis Laboratory (advanced)
This event pertains to the whole country
New outbreaks
-------------
Outbreak 1 Lake Ontario, Ontario
Date of start of the outbreak 25 Sep 2010
Outbreak status Resolved (02 Nov 2010)
Epidemiological unit Lake
Water type Fresh water
Population type Wild
Production system Open
Affected animals
Species Brown bullhead (_Ameiurus nebulosus_)
Morbidity 1 (scale 0-5)
Mortality 0 (scale 0-5)
Susceptible
Cases
Deaths
Destroyed 0
Slaughtered: 0
0
Affected Population The affected animals were adult catfish.
Summary of outbreaks
Total outbreaks: 1
Outbreak statistics:
Species: Brown bullhead (_Ameiurus nebulosus_)
Apparent morbidity rate **
Apparent case fatality rate **
Apparent mortality rate **
Proportion susceptible animals lost* **
* Removed from the susceptible population through death, destruction
and/or slaughter
** Not calculated because of missing information
Epidemiology
------------
Source of the outbreak(s) or origin of infection Unknown or
inconclusive
Epidemiological comments This event was not associated with a
visible die-off of finfish. This finding represents a new geographic
location and a new species (brown bullhead, _Ameiurus nebulosus_). On
25 Sep 2010, sick fish were found in Hamilton harbour. The water
temperature at the time of collection was 19 degrees Celsius. 7 adult
brown bullheads were sent to Fisheries and Oceans Canada (DFO) for
diagnostic work up. Another sample, 16 morbid adult brown bullheads,
was submitted to DFO from the same location on 2 Nov 2010. On both
submissions fish had deep ulcers on the head, base of fins and belly.
Histological findings include severe mycotic ulcerative dermatitis and
necrotizing granulomatous sub-acute myositis. Fungal structures were
non-septate with occasional branching hyphae. No reproductive fungal
structures were seen. Ulcerative lesions were also infected with
bacteria.
Control measures
Measures applied:
* Movement control inside the country
* No vaccination
* No treatment of affected animals
Measures to be applied Zoning Surveillance outside containment and/or
buffer zone
Diagnostic test results:
Laboratory name and type Freshwater Institute (National laboratory)
Tests and results
Species Brown bullhead (_Ameiurus nebulosus_)
Test histological test
Test date 28 Feb 2011
Result Positive
Species Brown bullhead (_Ameiurus nebulosus_)
Test polymerase chain reaction (PCR
Test date 28 Feb 2011
Result Positive
Future Reporting: The event is resolved. No more reports will be
submitted.
--
Communicated by:
ProMED-mail
<promed@promedmail.org>
[This is not the 1st report of this disease in Canada, but it is an
expansion of the disease
Epizootic ulcerative syndrome (EUS) is a seasonal epizootic condition
of wild and farmed, fresh- and brackishwater fish. Of complex
infectious aetiology, it is characterized by the presence of invasive
_Aphanomyces_ infection and necrotising ulcerative lesions typically
producing a granulomatous response. The disease is now endemic in
South-east and south Asia, and has recently extended to West Asia. EUS
is indistinguishable from red spot disease of eastern Australia and
mycotic granulomatosis of Japan.
Diagnosis is based on clinical signs and histological evidence of the
typical aggressive invasiveness of the non-septate fungal hyphae,
within the context of high mortality. Isolation of the fungus allows
its characteristic growth profile to be used as an aid to
identification.
Control of EUS in natural waters is probably impossible. In outbreaks
occurring in small, closed water bodies, liming of water and
improvement of water quality, together with removal of infected fish,
is often effective in reducing mortality.
The initial sign is usually mass mortality associated with distinct
dermal lesions including ulcers. Surviving fish typically have lesions
of varying degrees of severity. These may appear as red-spots,
blackish burn-like marks, or deeper ulcers with red centers and white
rims. Some fish, especially snakeheads survive a long time with such
ulcers, which may erode so deeply as to expose the vertebrae, brain
and viscera.
Histological occurrences include necrotizing, granulomatous
dermatitis and myositis associated with invasive, non-septate fungal
hyphae, 10-20 um in diameter. The fungus may penetrate visceral
organs, such as the kidney and liver, after it has spanned the
musculature.
The fungus can be isolated and cultured without difficulty, provided
measures are taken to exclude bacterial and other fungal contaminants.
Besides their typical vulnerability to temperature above 30C, _A
invaderis_ and _A. piscicida_ are very similar to non-pathogenic
opportunistic _Aphanomyces_ spp. that readily contaminate the surface
of affected fish and often interfere with isolation attempts. In the
laboratory, the fungus has also been shown to be pathogenic to a wide
range of fish, inducing similar pathology and mortality under various
predisposing experimental conditions.
Portions of this comment were extracted from:
<http://library.enaca.org/Health/DiseaseLibrary/EpizooticUlcerativeSyndrome.pdf>
- Mod.TG
The interactive HealthMap/ProMED map for Lake Ontario, Canada, is
available at:
<http://healthmap.org/r/01h7> - CopyEd.EJP]
[see also:
See Also
2010----
Ulcerative mycosis, fish - USA: (FL) 20101118.4176
2009
----
Epizootic ulcerative synd., fish - Southern Africa: (Zambezi River)
20090722.2593
2008
----
Epizootic ulcerative synd., fish - Australia (NSW) 20080320.1074
2007
----
Epizootic ulcerative synd., fish - Zambia (Zambezi River)
20070916.3077
Epizootic ulcerative synd., fish - Southern Africa (Zambezi River)
20070718.2301
Epizootic ulcerative synd., fish - Zambia (Zambezi River): susp., RFI
20070729.2437
Epizootic ulcerative synd., fish - Southern Africa (Zambezi River)
20070718.2301
1998
----
Epizootic ulcerative syndrome, carp - Pakistan (02) 19980120.0159
.................................................sb/tg/ejp/dk
*##########################################################*
************************************************************
ProMED-mail makes every effort to verify the reports that
are posted, but the accuracy and completeness of the
information, and of any statements or opinions based
thereon, are not guaranteed. The reader assumes all risks in
using information posted or archived by ProMED-mail. ISID
and its associated service providers shall not be held
responsible for errors or omissions or held liable for any
damages incurred as a result of use or reliance upon posted
or archived material.
************************************************************
Donate to ProMED-mail. Details available at:
<http://www.isid.org/ProMEDMail_Donations.shtml>
************************************************************
Visit ProMED-mail's web site at <http://www.promedmail.org>.
Send all items for posting to: promed@promedmail.org (NOT to
an individual moderator). If you do not give your full name
name and affiliation, it may not be posted. You may unsub-
scribe at <http://www.isid.org/promedmail/subscribe.lasso>.
For assistance from a human being, send mail to:
<postmaster@promedmail.org>.
############################################################
############################################################