Wiping out scrapie in goats, the genetic way

Posted on January 17, 2020 by Douglas Powell

More consumers are developing a taste for goat cheese, milk, and meat as they become aware of the high protein and great taste of these products. While U.S. goat producers are enjoying this steady trend, they remain focused on keeping their animals healthy, especially from scrapie—a fatal brain disease that affects goats and sheep.

“The goat industry is one of the fastest growing animal industries in agriculture,” says Stephen White, an Agricultural Research Service (ARS) geneticist. “Not too many years ago, there were only a few hundred thousand goats in the country.” But in January 2018, goats and kids totaled 2.62 million head.

Meat and dairy are the biggest markets, followed by mohair, but goats serve in other unique capacities, says ARS veterinary medical officer David Schneider. Goats are being used to manage weedy areas along highways, get rid of kudzu in the Southeast, and even mow lawns. They’re also used as pack animals to carry supplies through rugged areas.

For any of these businesses, a single outbreak of scrapie could be devastating.

There is no cure or treatment for scrapie, which is in the same family—transmissible spongiform encephalopathies (TSEs) or prion diseases—as mad cow disease. TSEs are rare degenerative brain disorders characterized by tiny holes that give the brain a “spongy” appearance.

Most often scrapie is transmitted through birth fluids to other goats and sheep, and it can remain infectious in the environment for many years. It was first recognized in sheep in Great Britain and other European countries more than 250 years ago and was first diagnosed in U.S. sheep in 1947 in a Michigan flock.

All animals that get scrapie die. But there is good news from ARS. White and Schneider, who both work at ARS’s Animal Disease Research Unit in Pullman, Washington, are the first to demonstrate by infectious disease challenge that goats with the S146 allele (a different form of a gene) are less susceptible to scrapie over a usual goat lifetime. They also tested the K222 allele in goats. Their research shows that goats with one copy of either the S146 or K222 allele did not develop scrapie after being challenged with infection at birth. The study was published in The Veterinary Journal in 2018.

“Commercial goats raised for either meat or milk age out of herd participation as milkers, dams of commercial offspring, or as sires by around 6 years of age,” White says. In this ongoing ARS research, goats with the resistance alleles have lived beyond this commercial lifetime—up to 7½ years—with no clinical disease and without getting sick.

The only countries considered to be scrapie free are Australia and New Zealand. Currently, if one goat is diagnosed with scrapie on a U.S. farm, all goats are quarantined for life or euthanized. “You couldn’t restock your operation with any susceptible animal,” White says. “The farmer’s operation would be over.”

This research is good news for both goat and sheep producers because it could help with eradication efforts. Before U.S. producers can take advantage of import and export markets, scrapie must be eradicated from the United States and meet the World Organisation for Animal Health (OIE) criteria for disease freedom.

Can scrapie in sheep cause disease in humans?

Posted on August 10, 2015 by Douglas Powell

On March 20, 1996, British Health Secretary Stephen Dorrell rose in the House to inform colleagues that scientists had discovered a new variant of Creutzfeldt-Jacob disease (CJD) in 10 victims, and that they could not rule out a link with consumption of beef from cattle with bovine spongiform encephalapthy (BSE), also known as mad cow disease.

The announcement of March 20, 1996 was the culmination of 15 years of mismanagement, political bravado and a gross underestimation of the public’s capacity to deal with risk. More important than any of the several lessons to be drawn from the BSE fiasco was this: the risk of no-risk messages. For 10 years the British government and leading scientific advisors insisted there was no risk — or that the risk was so infintesimly small that it could be said there was no risk — of BSE leading to a similar malady in humans, CJD, even in the face of contradictory evidence. The no-risk message contributed to the devastating economic and social effects on Britons, a nation of beefeaters, the slaughter of over 1 million British cattle, and a decrease in global consumption of beef, especially in Japan, at a cost of billions of dollars.

Part of that logic stemmed from the apparent absence of zoonotic or human effects from the sheep transmissible spongiform Encephalopathy, scrapie, which had been know in the UK for hundreds of years.

European researchers have now reviewed the available evidence.

The factors that modulate the transmissibility of Transmissible Spongiform Encephalopathies (TSE) and the approaches for the study of their zoonotic potential are reviewed. The paper ‘Evidence for zoonotic potential of ovine scrapie prions’ by Cassard et al. (2014) is scientifically appraised, focussing on the experimental design, the results and the conclusions.

The paper provides evidence in a laboratory experiment that some Classical scrapie isolates can propagate in humanised transgenic mice and produce prions that on second passage are similar to those causing one form of sporadic Creutzfeldt-Jakob disease (sCJD). It is concluded that the results from the study raise the possibility that scrapie prions have the potential to be zoonotic, but do not provide evidence that transmission can or does take place under field conditions.

The conclusions of the 2011 ECDC-EFSA ‘Joint Scientific Opinion on any possible epidemiological or molecular association between TSEs in animals and humans’ are reviewed in the light of the new scientific evidence available since its publication. This supports and strengthens the conclusions of that opinion with regard to the potential for some animal TSE to be zoonotic, but does not provide evidence of a causal link between Classical or Atypical scrapie and human TSE. Current evidence does not establish this link, and no consistent risk factors have been identified for sCJD.

The possibility of scrapie-related public health risks from the consumption of ovine products cannot be assessed. Recommendations are formulated on further studies and data that are needed to investigate the zoonotic potential of animal TSE and to estimate the amount of infectivity from TSE-infected products sourced from small ruminants and entering the food chain in the European Union.

Scientific Opinion on a request for a review of a scientific publication concerning the zoonotic potential of ovine scrapie prions

EFSA Journal 2015;13(8):4197 [58 pp.]. doi:10.2903/j.efsa.2015.4197

EFSA Panel on Biological Hazards (BIOHAZ)

http://www.efsa.europa.eu/en/efsajournal/pub/4197.htm?utm_source=feed&utm_medium=rss&utm_campaign=ej

Scrapie from lambs could infect humans like ‘mad cow disease’, research suggests

Posted on December 18, 2014 by Douglas Powell

Or not.

Creuzfeldt Jakob Disease (CJD), known more commonly as ‘mad cow disease’, caused a major scare in the 1990s. But now it’s lambs rather than cows that some are concerned about.

A question mark over the safety of lamb has been raised after scientists found that a deadly brain disease affecting sheep has the potential to infect humans.

The disease, named scrapie, is similar to variant CJD that previously spread from cows to humans through infected meat.

Researchers have now found evidence linking the infectious agent behind scrapie with sporadic CJD (sCJD), a fatal human disease thats cause has never been known.

The scientists stress they have no proof that eating mutton or lamb infected with scrapie can lead to sCJD in humans.

But tests on humanised laboratory mice show that potentially scrapie is capable of infecting humans. And the way the infection spreads in the brain is identical to that seen in cases of sCJD.

The scientists, led by Dr Olivier Andreoletti, from the National Veterinary School of Toulouse in France, wrote in the journal Nature Communications: “Our data on their own do not unequivocally establish a causative link between natural exposure to sheep scrapie and the subsequent appearance of sCJD in humans.

“However, our studies clearly point out the need to consider this possibility.”

Both scrapie and different forms of CJD are caused by rogue misshapen prion proteins.

Normal prions that come into contact with the defective versions are changed too and turn “bad”. In this way the infection spreads, inflicting terrible damage to the brain.

Sheep heads illegally on sale in London supermarket

Posted on February 27, 2014 by Douglas Powell

Six sheep heads found illegally on sale in a supermarket in Edmonton, northern London, have been seized after Enfield Council discovered them during a routine inspection.

The grisly-looking skulls, which were believed to be more than four years old, were found with their teeth still attached last night by its Food Safety Team and immediately removed from sale.

The heads have the potential to carry scrapie and the supermarket had no documentation as to where and when they were bought, which the council called ‘incredibly concerning’.

It said the matter was ‘now subject to further investigation’, with Cabinet Member for Environment, Cllr Chris Bond, adding: “There are very good reasons why we have strict controls in place regarding food safety associated with meat and its incredibly irresponsible of this trader to flout these regulations.

“We take this sort of behaviour incredibly seriously and take a very dim view of people who simply cannot be bothered to take the proper legal precautions to protect the public from exposure to a potentially fatal disease.

“The business in question had no records of when and where they purchased these heads, which is incredibly concerning because anyone buying and ultimately eating them, doesn’t have the faintest idea of what they are eating.

“It is a legal requirement for all businesses to ensure they have documentation for all food they are supplied with and that reputable suppliers are used.”

Scrapie sheep kidnappers say infected flock in protective custody

Posted on April 30, 2012 by Douglas Powell

PC may be politically correct, but in jail it means protective custody, not much better than the hole.

Two days after the Canadian Food Inspection Agency confirmed scrapie in a recently deceased sheep from a quarantined flock in Eastern Ontario, and a month after CFIA was scheduled to confiscate the Shropshire sheep, the previously unknown group Farmers’ Peace Corps kidnapped the 31 sheep slated for slaughter, leaving a note that read:

“We have taken the animals into protective custody until an alternative to killing has been found, or conclusive independent proof or clear evidence of disease has been proven. This has been done without the knowledge or participation of the owner.”

What say the people’s front now that scrapie has been confirmed? Not independent? Testing for scrapie or other transmissible spongiform encephalopathies isn’t something that can be done in a basement, like genetic engineering.

The Globe and Mail reports that on Friday, CFIA notified Ms. Jones that an autopsy showed a sheep that died at the end of March on the farm was infected with scrapie.

Montana Jones, the owner, said, “I don’t believe Lava (the name of the sheep) was actually infected. They just needed a sheep to pin it on. I just want whoever has my flock to bring it back to me and then everybody leave me alone.”

CFIA said in its positive test announcement that Canada’s approach to confirmed or suspected cases of scrapie is based on internationally accepted science and seeks to minimize disruptions to producers.

The missing sheep pose a serious risk for scrapie and could spread the disease to other sheep and goats. Any premises that receive them will be subject to a quarantine and further regulatory action.

Quarantine breaches put the livestock industry and the economy at risk. Any person who breaches a quarantine may be subject to criminal prosecution under the Health of Animals Act.

Atypical scrapie in single NZ sheep

Posted on October 27, 2009 by Douglas Powell

Contrary to what the New Zealand Herald reported tonight (this morning in NZ), the animal in question was born in NZ, not the UK, because NZ does not import sheep from the UK.

MAF Biosecurity New Zealand (MAFBNZ) and the New Zealand Food Safety Authority (NZFSA) today confirmed that a series of New Zealand and European laboratory tests on a single New Zealand sheep brain have detected the condition atypical scrapie (also known as Nor 98).

Atypical scrapie/Nor 98 is a relatively recently discovered brain condition of sheep and goats that is quite different from the classical form of scrapie.

Neither atypical scrapie/Nor 98 nor scrapie is known to pose any risk to human health or the safety of eating meat or animal products.

MAFBNZ Principal International Adviser Dr Stuart MacDiarmid says global knowledge about atypical scrapie/Nor 98 is evolving. The widely accepted mainstream scientific view is that it occurs spontaneously or naturally in very small numbers of older sheep in all sheep populations around the world.

“This positive detection of atypical scrapie/Nor 98 in a sheep from New Zealand’s national flock reinforces that view. Every country that has conducted sufficient surveillance for atypical scrapie/Nor 98 has found it in their flocks. This includes most Scandinavian and EU countries, the UK, the USA and Canada,” he says.

The detection does not change New Zealand’s status as free from scrapie.

Dr MacDiarmid says because of this scrapie freedom status, New Zealand supplies sheep brains to the European Union for use in the development of tests for scrapie.

“The affected brain was one of a consignment of 200 brains sent for this purpose. EU-authorised tests carried out in New Zealand prior to shipment had not picked up anything unusual. However further tests in Europe and re-testing in New Zealand on different parts of the brain from the area originally tested have now established a diagnosis of atypical scrapie/Nor 98.

There is no evidence that atypical scrapie/Nor 98 can be transmitted naturally to other animals or to people, or that it in any way affects people.

If it’s not Scottish, it’s craaaaapp

Posted on January 20, 2008 by Douglas Powell

After 19 years, the Scottish government is bent on asking the United States to overturn its ban on Scotland’s traditional and national dish called ‘haggis.’

The U.S. implemented a ban on haggis from Scotland in 1989 amidst the bovine spongiform encephalopathy [mad cow] scare because the dish contains offal ingredients such as sheep lungs. Sheep can suffer from scrapie, which is in the same family of diseases as BSE.

A Scottish government spokesperson told BBC News,

"The market is massive because there are so many expat Scots there and once Americans try a good quality haggis, they can’t get enough of it."

A spokesman for the U.S. Department of Agriculture said,

"We do not allow importation because of the U.K.’s BSE status. Sheep are susceptible to TSE’s and thus the U.S. takes precautions on importing those ruminants from BSE-affected countries."

A spokesman for Britain’s Food Standards Agency said,

"We see no reason at all why people cannot eat haggis safely, so long as manufacturers follow hygiene legislation."

The story says that haggis is traditionally served with tatties and neeps (potatoes and turnips). It usually contains a sheep’s lungs, liver and heart minced with onion, oatmeal, suet, spices and salt mixed with stock. It is then boiled in the animal’s stomach for approximately three hours.

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