martes, 8 de octubre de 2019

ProMED-mail

ProMED-mail

ProMED logo

« prev

ProMED logo

Published Date: 2019-10-08 11:56:35
Subject: PRO/AH/EDR> Undiagnosed ulcerative disease - Ireland: salmon, trout
Archive Number: 20191008.6715400
UNDIAGNOSED ULCERATIVE DISEASE - IRELAND: SALMON, TROUT
*******************************************************
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: Fri 4 Oct 2019 11:43:00 IST
Source: Breaking News [edited]
https://www.breakingnews.ie/ireland/anglers-terrified-that-mysterious-disease-will-wipe-out-salmon-stocks-954933.html


Anglers in the north-east say they are 'terrified' that a mysterious virus could wipe out salmonid stocks across the country.

The undetermined disease, which causes bleeding and skin ulceration on salmon and sea trout, has still not been identified despite the best efforts of Inland Fisheries Ireland (IFI) and scientists internationally.

The affected salmon show signs of bleeding ulceration and haemorrhaging mainly along the area on the belly of the fish as well as the head and tail. Secondary fungal infection usually sets in and can result in death.

Local angling clubs in Louth and Meath say that hundreds of fish sporting a white skin fungus have been spotted in rivers throughout the country since last April [2019].

Since June [2019], anglers have been advised by the IFI to leave diseased salmon in rivers and disinfect tackle waders and equipment.

A dedicated email set up by the IFI since June [2019] has received 25 reports from 15 rivers nationwide.

Minister of State at the Department of Communications, Climate Action and Environment Deputy Sean Canney admitted the situation was 'a worry' when it was raised in the Dail by Louth's Fianna Fail [Republican Party] TD [constituency deputy] Declan Breathnach.

"Large numbers of fish have been found in the Boyne, Castletown, Dee and Fane rivers that appear deformed or diseased and there are serious concerns from the anglers about the risk of the disease spreading to humans," said Deputy Breathnach.

Alan Molloy, vice-chair of The Boyne Catchment Angling Association which includes 2000 anglers from 23 clubs described the situation among members as 'worrying.'

"Hundreds of people I've spoken to across many rivers nationwide have seen these salmonids with white fungus on them.

"The fungus is a secondary infection and scientists can't seem to identify the primary infection, despite their best efforts.

"We have given live samples to the IFI and have asked our members to report any incidents. Unfortunately because they are so familiar now, many are not bothering reporting incidents, thinking they've already been reported.

"We are heartened by Deputy Breathnach's efforts and the IFI's response that all the statutory bodies are taking this seriously and investigating.

"We have to bear in mind that salmon stocks have fallen in our rivers by 90% since the 1970s. Anglers are deeply frustrated and terrified that we're staring straight at the extinction of the iconic salmon from Irish waters happening in front of our eyes."

The sentiment was echoed by Liam Woods of the Dundalk Salmon Anglers Association who said: "It's a cruel fate that in the international year of the salmon, we are seeing this disease for the 1st time."

He added: "Anglers also from the Dundalk Salmon Angers Association, Balintra Anglers, Inniskeen Village Anglers, and Kells Anglers have all witnessed these diseased fish."

In June [2019], Inland Fisheries Ireland informed the angling community that 'a small number of salmon' were showing signs of bleeding and skin ulceration as they returned to Irish rivers and appealed to anglers to notify them of any incidents.

In a statement yesterday they say: "IFI collaborated with the fish health unit in the Marine Institute with samples from the River Erriff and River Lee supplied to them and further samples from the Boyne supplied to the Veterinary Group in Galway for testing.

"To date, no responsible disease has been identified. The majority of reports of diseased salmon occurred during June and July [2019] with small numbers of reported incidents since that time.

"Given the international dimension to the issue, scientists from IFI have been collaborating with colleagues in Norway and Scotland in an effort to establish the cause of the disease.

"At this time, no laboratory in Europe has definitively identified the cause of the symptoms. However, an emerging theory is that it may be due to a change in salmon diet and a related vitamin deficiency.

"IFI continues to work with international scientists to exchange knowledge about the disease and the results of disease testing between countries."

Deputy Sean Canney admitted in his reply to Deputy Breathnach: "From a personal point of view, the local anglers are the people who have the local knowledge and that is what will help us solve this problem, but it is a worry."

[Byline: Louise Walsh]

--
Communicated by:
ProMED-mail from HealthMap Alerts
<promed@promedmail.org>

[Skin lesions in fish can be caused by a variety of infectious and noninfectious insults. Lesions commonly are caused by opportunistic pathogens, which infect weakened or stressed hosts. These pathogens, which include bacteria, fungi, viruses, and parasites, may gain entry because of impaired immune or disease resistance factors, or because the natural defense mechanisms of the skin are impaired or breached.

A similar disease of salmonids native to the waters of the British Isles is ulcerative dermal necrosis (UDN). However, in UDN lesions are predominantly observed in the head skin. It was first reported in the 19th century. The disease largely disappeared until the mid-1960s when it first occurred in southwest Ireland and then gradually spread to almost all rivers of the British Isles and subsequently to neighbouring areas.

Salmon (_Salmo salar_) and sea trout (brown trout, _Salmo trutta_) are susceptible to UDN. The disease is characteristically found in adult wild fish as they congregate at sea prior to entering fresh water and during their upstream river migration. The lesion is a progressive cytolytic necrosis of epidermal Malpighian cells, of the pemphigoid type which is restricted to specific sites on the head. On entry to fresh water, these rapidly ulcerate and may become infected with a number of opportunistic pathogens, principal of which is the oomycete _Saprolegnia diclina_. Once this occurs the lesion extends by fungal activity, death being due either to secondary bacterial infection of the ulcer or, more often, circulatory failure resulting from the osmotic hemodilution induced by the large area of ulceration.

The condition is primarily found in the colder months of the year and usually persists at high for 3 or 4 years in a river system after which it gradually disappears. Attempts to isolate a specific viral or bacterial agent from the lesions, or from other organs, have failed and the evidence that UDN is an infectious disease is very limited. Investigation into other more complex possible etiologies have been equally unsuccessful.

This new disease, similar to UDN with a different body distribution, seems to also have an elusive etiology. The coincidence of taxonomic group affected (salmonids) and the region invite considering a shared origin.

Portions of this comment were extracted from the review article "Roberts RJ. Ulcerative dermal necrosis (UDN) in wild salmonids", Fisheries Research. 1993; 17(1-2): 3-14; http://www.sciencedirect.com/science/article/pii/016578369390003P. - Mod.PMB

Maps of Ireland: https://www.mapsofworld.com/ireland/maps/ireland-political-map.jpg and http://healthmap.org/promed/p/26860]

See Also

2015
----
Ulcerative dermal necrosis, salmon - UK: (England) 20150810.3569208
2012
---
Ulcerative dermal necrosis - UK: (Scotland) 20120602.1154426
.................................................sb/pmb/mj/lxl

ProMED logo
Publicado por en

No hay comentarios:

Publicar un comentario

Suscribirse a: Enviar comentarios (Atom)