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Explainer: What is BSE - and should we be concerned about this Scottish case?

A case of Bovine Spongiform Encephalopathy (BSE) has been confirmed on a farm in Aberdeenshire

shutterstock_439195429 Source: Shutterstock/Studio Peace

A CASE OF Bovine Spongiform Encephalopathy (BSE) has been confirmed on a farm in Aberdeenshire, the Scottish government has said.

Precautionary measures have now been put in place at the farm, with investigations underway to identify the origin of the disease.

An “isolated case” of classical BSE was identified in Louth in 2015 – this was the last reported case of the disease in Ireland. 

In light of today’s news, TheJournal.ie has decided to break it down … what is BSE – or Mad Cow Disease? And why are people concerned about this case? 

BSE… What is it? 

Bovine Spongiform Encephalopathy (BSE) is a disease that affects adult cattle.

It attacks the brain and central nervous system of the animal – and eventually causes death.

Commonly known as Mad-Cow Disease, it has a long incubation period, meaning that it usually takes four to six years for infected cattle to show signs of the disease.

Symptoms include disorientation, clumsiness – and, occasionally, aggressive behaviour towards other animals and humans.

Where does BSE come from? 

BSE was first confirmed in cattle in the UK in 1986.

The first case in Ireland was confirmed in 1989 – when there were 15 cases confirmed.

The brain disease ‘Scrapie’ was first recorded in sheep way back in 1732 – and was first discovered in a cow in France 1883.

It’s believed it reappeared in cattle between the 1970s and 80s when changes in the ‘rendering’ process meant it ‘jumped species’ (see below).

What happened in the 1990s?

While the case confirmed today was found in Scotland, let’s take a quick moment to look at the Irish BSE crisis in the 1990s.

The BSE crisis, which reached its peak in Ireland the mid-1990s, was hugely damaging to the industry.

The Irish Farmers Association estimated back in 1996, when the crisis was at its worst, that it had knocked over £1 billion (in punts) off the value of the cattle herd.

Tens of thousands of cattle were culled in response.

Agriculture Industry Source: Mark Stedman via RollingNews.ie

How does it spread? 

Most experts agree that BSE was most likely spread by cattle eating feed that contained contaminated Meat and Bone Meal (MBM) – produced in a process called rendering (where otherwise unused animal products are taken from the carcass and are cooked for a long time).

MBM was incorporated into cattle feed until it was banned in the 1990s.

Experiments have shown that cattle can contract BSE if they are fed infected brain tissue. This seems to support the idea that BSE was transmitted to cattle through their animal feed.

What controls have been put in place?

The practice of feeding Meat and Bone Meal to cattle has been banned in Ireland since 1990.

Controls on MBM were strengthened in 1996 -1997.

Due to the BSE crises in other member states, a ban was introduced throughout the EU on feeding MBM to all farm animals in 2001.

(Note: More detail on controls available from the FSAI and Department of Agriculture)

What is the danger to people? 

BSE only develops in cattle – but it belongs to a family of prion diseases, several of which can affect humans.

The most commonly known disease in this group among humans is Creutzfeldt-Jakob Disease (CJD) – a rare and fatal form of dementia that normally occurs in people aged between 40 and 80.

CJD is not a new disease among humans – but in 1996, scientists discovered a new strain of CJD that occurs predominantly in younger people.

Human BSE memorial Day Thomas Goodwin from Glasgow, father of Grant (in picture) who died aged 30 from vCJD, marks Human BSE memorial Day in London in 2010. Source: PA Archive/PA Images

Evidence has shown that the protein that accumulates in the brains of patients with this new form of CJD is similar to the protein found in cattle infected with BSE, rather than that found in classical CJD.

Because of this discovery, the new illness in humans is known as variant CJD or vCJD.

What’s the link?

The occurrence of the new form of CJD in the UK , where there was a high incidence of BSE, suggested that there might be a direct link between BSE and vCJD.

Some people who had developed vCJD were known to have eaten potentially BSE-infected meat products.

Researchers concluded that the most likely origin of the new disease was human exposure to the BSE agent.

Like BSE in cattle, vCJD is always fatal in people.

So, is there any risk of it spreading further? 

Precautionary measures have now been put in place at the farm, with investigations underway to identify the origin of the disease.

The affected animal did not enter the human food chain, so there is no risk to human health, authorities have said. 

“Consumers can be reassured that [...] important protection measures remain in place,” Ian Watt, director of operations in Food Standards Scotland, said.

Cruises on the Shannon Source: Eamonn Farrell via RollingNews.ie

Chief veterinary officer Sheila Voas said that while it’s too early to tell where the disease came from, it was proof its surveillance system is doing its job.

So, as the Scottish government has stressed, the general public will not have been put at risk in this case. 

Rural economy secretary Fergus Ewing said: “While it is important to stress that this is standard procedure until we have a clear understanding of the diseases origin, this is further proof that our surveillance system for detecting this type of disease is working.”

In a statement to TheJournal.ie, the Department of Agriculture said it had noted the announcement and measures taken to investigate its source.

A spokeswoman said: “It is not wholly unexpected to find an occasional isolated case at the end of any disease epidemic.

“The Department notes that Scottish authorities are taking the appropriate measures to investigate the possible source and to identify and investigate any cohort or progeny animals which may be at risk.” 

In a statement released today, the Department of Agriculture, Food and the Marine said that “it is not wholly unexpected to find an occasional isolated case at the end of any disease epidemic.

The Department notes that Scottish authorities are taking the appropriate measures to investigate the possible source and to identify and investigate any cohort or progeny animals which may be at risk.

[Sources: FSAI, Department of Agriculture, Bord Bia, IFA, TheJournal.ie, Guardian] 

With reporting by Daragh Brophy and Sean Murray

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