Summary Report on the Epidemiological Investigation into the suspect BSE case – 25 June 2015
- Background
On Tuesday 9th June, DAFM identified a positive result in a rapid screening test (Idexx EIA) carried out by aDAFM 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 weresubsequently forwarded to the National Reference Laboratory where samples from different brain areas were subject to confirmatory testingusing an OIE-approved confirmatory Western Blot method (Biorad TeSeE).In addition thesamples were subject to a two-blot protocol for the classification of BSE isolates.
The results became available late on the evening on 10thJune.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 areOIE 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 considerevents 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 - andalso the ‘progeny’ of the suspect animal.
- 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 issimilar 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 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 thecase 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 withmeat and bone meal.
- 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
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-layeredcontrol system, in Ireland and the EU, continues in place to mitigate any such risks.
The controlsystem 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 speciesand the associated controls to ensure implementation, as well as a range of further control measures.
END
25 June 2015
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