Summary Report on the Epidemiological Investigation into the
suspect BSE case – 25 June 2015
1. Background
On Tuesday 9th June, DAFM identified a positive result in a rapid screening test (Idexx EIA)
carried out by a DAFM approved, accredited private laboratory. The animal in question had
been sampled by DAFM staff at a knackery on the evening of Monday 8th June, as part of the
on-going official sampling of all fallen (died on farm) animals of 48 months and older. This
sampling is one element of a comprehensive control programme systematically applied in
Ireland.
The sample material and the brain were subsequently forwarded to the National Reference
Laboratory where samples from different brain areas were subject to confirmatory
testing using an OIE-approved confirmatory Western Blot method (Biorad TeSeE). In
addition the samples were subject to a two-blot protocol for the classification of BSE
isolates.
The results became available late on the evening on 10th June. All the samples had an
identical molecular pattern indicating classical BSE. In accordance with NRL protocols,
samples from the animal were then sent forward for histopathology and
immunohistochemistry on the medulla of the brain. These are OIE confirmatory testing
methods for BSE. In addition, samples were also forwarded to the EU Reference Laboratory
in Weybridge, UK.
The carcase was detained and taken away for destruction. No part of the carcase entered
the feed or food chain.
Final confirmatory test results were received from both laboratories on 25th June,
confirming the case to be classical BSE.
The Department commenced an epidemiological investigation immediately on the animal
being confirmed to be suspect. The investigation set out to consider events that happened 5
years previously. The initial focus was on identifying other animals that were of potential
risk of having been exposed to the BSE agent at the same time as the suspect animal – the
‘cohorts’ – those animals born and reared in the same herd in and around the same time and also the ‘progeny’ of the suspect animal.
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2. Investigation
Animal
The animal in question was born on 14/01/2010 and it was 65 months old at the time of its
death. The animal was born, reared and had spent its entire life on the same farm. The
farmer reported that the animal had fallen 7-10 days after it had calved on 24/02/15 but
had recovered. The animal fell once again on 06/06/15. The animal did not recover and the
farmer took the decision to have the animal euthanased. The carcase was removed to a
knackery, where it was sampled by DAFM veterinary staff as part of the official control
system. The clinical history subsequently reported by the farmer is similar to clinical
histories seen in other classical BSE cases.
The grand-dam of the animal was imported in 2002. The importation of this animal had no
significance in relation to its second generation offspring being diagnosed with BSE.
Additionally, both the dam and grand-dam of the infected animal were tested when they
were slaughtered as healthy animals in 2006 and in 2013. Both animals tested negative for
BSE. It is also worth noting that there has never been a case of BSE identified in the offspring
of BSE positive dams in Ireland.
Herd
The farm of birth of the case was a dairy farm, comprising a herd which was assembled in
2002, following the depopulation of the previous herd due to the diagnosis of BSE.
The identification of the ‘cohort’ group, in line with normal protocols, took into account
animals born in the herd in the same year (2010) as the case animal, in the previous year
(2009) and the following year (2011). The objective was to identify those animals which
might have consumed the same feed as the case animal. We identified 63 such animals still
alive and 4 progeny of the case animal in a total of 7 herds. All progeny and cohorts were
flagged on our AIM IT system to prevent their movement.
All 67 animals that had been identified, traced and restricted were removed and
slaughtered on 22nd June. Samples from all these animals were subjected to testing for BSE.
Results from these tests were delivered on 23rd June – all 67 animals tested negative.
The occurrence of a second case of BSE on a farm that had a previous case, whilst not
common, is not a new phenomenon, either in Ireland or in other countries. Ten farms in
Ireland were unfortunate enough to experience double depopulations i.e. initial herd
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removed, premises cleaned and disinfected and farm repopulated with animals bought into
the premises. There are similar reports of repeat occurrence from other countries.
As classical BSE has traditionally been associated with oral exposure to the infective agent,
an investigation into the feeding regime, including source of feed was undertaken. This
focussed on feeds to which the case animal may have had access during its first year of life,
and on the manufacturing practices used to produce these feeds. There is a ban on the
feeding of meat and bone meal to ruminants while non-ruminant meat and bone meal may
be fed to aquaculture animals under strict conditions. All feeds found to have been utilised
on the farm in the 2009/2010 period were sourced from five licensed suppliers. There were
no other species on the farm where any mix-up in feed could occur and there is no evidence
that any of the feed came from unlicensed sources.
The Departments feed controls with respect to the ban on the use of processed animal
proteins involved 2,021 inspections and the analysis of 1,279 samples in 2009 and 1,783
inspections and 1,180 samples analysed in 2010. All samples tested negative for the
presence of meat and bone meal and the inspections did not identify any issues of concern
in this regard. More specifically 52 samples related directly to the five suppliers of feed to
the case farm and these tested negative. In addition, tests were conducted on samples of
feed currently on the farm and these too were found to be negative.
The possibility of cross contamination at a feed-mill was also evaluated. Whilst there are a
number of multispecies feed mills (manufacturing ruminant, poultry, horse, pigs etc) in the
country, these premises do not incorporate meat proteins in their products. There is only
one mill in Ireland that is specially approved by DAFM to incorporate fishmeal and/or blood
products into animal feed, however that mill is manufacturing feed for pigs only and did not
supply this farm. None of the 5 feed suppliers to the farm are manufacturing pet food
containing meat proteins.
No evidence has been found either on the farm or in the mills that supplied the farm, of
contamination or the risk of contamination of feed with meat and bone meal.
3. Conclusion
The test results indicate that this is a case of classical BSE. The investigation has confirmed
that this is an indigenous case, born and reared in Ireland. The evidence gathered during the
investigation does not support the hypothesis that the case has arisen from vertical
transmission from dam to off-spring. Furthermore the evidence gathered supports the view
that the feed manufacturing and feed supply chain is well controlled and was not a
contributory factor in the epidemiology of the disease in this case
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The identification of classical BSE cases after the implementation of the reinforced ban on
the feeding of meat and bone meal is not unprecedented. A diminishing number of such
cases have been identified in Ireland and in other countries over the years. We will share
our findings of this investigation with others finding similar type cases, with a view to
further investigating the source. The multi-layered control system, in Ireland and the EU,
continues in place to mitigate any such risks.
The control system that has brought BSE under control is still in place. Human health
continues to be protected by the ante-mortem inspection of animals by veterinarians before
being allowed into the food chain and the removal and destruction of tissues shown to be
capable of transmitting infection (Specified Risk Materials). Animal health continues to be
protected by the ban on the feeding of ruminant meat and bone meal to all farmed animal
species and the associated controls to ensure implementation, as well as a range of further
control measures.
END
25 June 2015
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