A sheep farmer’s worst nightmare is if one of his sheep starts to scratch more than usual. If their sheep start to show nerves, tremble, or grind their teeth, they should be really worried. An unstable walk or sheep that spend most of the time lying down might be showing symptoms of scrapie, the ovine version of mad cow disease.
Scrapie isn’t spread by bacteria or a virus – it’s thought to be caused by a prion protein. The result is a fatal, degenerative disease that affects the infected animals’ nervous system. While bacteria and viruses are hard to deal with, prion proteins are in a league of their own, nearly impossible to get rid of. They can withstand an eight-hour boil and only the strongest chemicals will clear them. For sheep, an infection is a death sentence, effectively turning their brains into mush. There is no cure.
Do you know what happens if a farmer’s sheep test positive for scrapie? The entire herd is culled, as soon as possible, sometimes even sheep from surrounding farms as well. All sheep that have stayed at the infected farm will also be culled. The farmer won’t be permitted to have sheep on the farm for a certain period of time and must destroy all their hay. For the next ten years, every visitor to the barns will have to be notified of the danger of infection.
The local veterinarian decides what needs to be disposed of and what can be sanitised. And we’re not talking only about equipment but whole barns. The barns and everything in them must be disinfected with strong chemicals or fire and everything must be repainted. Finally, the soil around the barns is exchanged for new material and the area is paved. The government pays some damages, but it’s not likely that they will cover the financial loss, let alone the emotional damage of having your life’s work methodically wiped out – let alone the death toll.
The only person
When Karólína Elísabetardóttir visited Iceland for the first time, she fell in love with the country, its nature, and the animals; horses and sheep. It was a coincidence that led her, some years later, to buy some land and start a farm. Located halfway up a mountain pass in North Iceland, her estate is large but mostly consists of a mountain and a river. It hadn’t been farmed for over a century so there are no cultivated fields. When asked if she ever gets lonely on her mountaintop, Karólína simply replies: “I’m not alone, I’m just the only person.” Her four horses, two dogs, and herd of sheep keep her company. They also provide her livelihood. She raises her sheep for their wool and provides the opportunity for people to foster sheep. In exchange for their patronage, they receive a fleece of wool each spring, when Karólína ships wool in all the colours of a sheepish rainbow to her customers. Since she isn’t worried about meat production, she has the freedom to breed tall and lean sheep, which make them better equipped to navigate her mountainous land, and while many wool farmers prefer white sheep, she looks for interesting colours. It takes years to breed a herd to a farmer’s specific liking. One unfortunate contact with an infection could bring her back to square one.
He’s a born and bred farmer, the sixth generation of his family living in Sveinsstaðir, along with his wife Inga Sóley Jónsdóttir.
A farmer by blood
Ólafur Magnússon is a farmer at Sveinsstaðir in North Iceland, a 40-minute drive from Karólína’s mountain. He’s a born and bred farmer, the sixth generation of his family living in Sveinsstaðir, along with his wife Inga Sóley Jónsdóttir. His ancestral home was built in 1929 and his herd of sheep are the direct descendants of sheep brought there in the 1940s. Until he lets them out to pasture in spring, they reside in a bright and airy barn, recently tripled in size. In contrast to Karólína’s sheep, the group mostly consists of white sheep and almost every one of them has horns. “Every farmer has his own quirks like that,” Ólafur tells me. “I think the horned sheep are the prettiest, but others prefer the look of polled sheep.”
Sveinsstaðir has never had a case of scrapie, nor have the surrounding farms, despite the disease being endemic in the region. In the next valley over, however, Ólafur knew a farmer facing the constant threat of the disease as it popped up on farms all around them. “If it didn’t happen this autumn, they had to be prepared for it to rear its head next year, or the year after that. You can’t really focus on developing your breeding program or your farm with this hanging over you.”
He’s a born and bred farmer, the sixth generation of his family living in Sveinsstaðir, along with his wife Inga Sóley Jónsdóttir.
Figuring it out
About a year ago, Ólafur got a message from Karólina. Despite the relatively short distance between their farms, he didn’t know her personally. But Karólína had been reading up on scrapie. She knew what a scrapie infection would mean and she wasn’t too keen on having that happen on her own farm, where her herd of sheep was so entwined to her life that they would come when she calls them. And if it wasn’t evident from the life she had carved out for herself on her mountain, if Karólina set her mind to something, things got done. “I thought that there must be another way,” Karólína told me. She read up on the research Stefanía had done in Keldur. In fact, she read everything she could find on the subject. “I know some veterinarians and sheep farmers in Germany and other countries and that was the reason that I started looking into the genotypes.”
Digging through DNA
Through her contacts, she got in touch with Christine Fast in Greifswald, Germany. They talked about the attempts to find the ARR genotype in Iceland. While no such sheep had been found in the first study, the word among farmers was that there might be something there. There was no research to support it, but some farms seemed to be shielded from scrapie cases, even though the disease was popping up all around them. “Then, Christine told me that there might be something else.” There was some evidence suggesting that they could look beyond the three codons usually studied to determine scrapie susceptibility and look for differently composed genotypes that might prove scrapie-resistant. “It was a spot of luck really, that at the same time, I found a report on research conducted in Italy, three studies that were carried out fifteen years ago,” Karólína says. “They found that a specific genotype that they called T137 seemed to be as resistant to scrapie as ARR.” This sparked something in Karólína’s brain. “I had read in Stefanía’s report from the scrapie study conducted in Iceland two decades ago, that T137 had been found in Icelandic sheep.” If they could find more of these sheep, there might be some hope. But that study had been made 20 years ago. Since then, several cases of scrapie had been discovered and several whole herds culled. Since 1996, 61 cases of scrapie had been detected on 58 farms in Iceland.
A looming threat
Karólína’s farm is in a designated scrapie region. It means that farms in the area regularly encounter outbreaks of the disease. In fact, this is the region where scrapie was first detected. In the late 19th century, an English ram was imported to Iceland via Denmark. It was a beautiful ram with many desirable qualities that farmers were excited to introduce to their own herds. But they got more than they bargained for: scrapie. Importing live sheep was banned in Iceland in 1882. Occasionally, over the following century, exemptions were made. In all but one of those cases, new diseases were introduced to Icelandic sheep. The last attempt was made in 1945, but the sheep were culled when found to suffer from footrot.
A way out
Now there’s a light at the end of the tunnel: breeding. At the turn of the millennium, studies found that some sheep are naturally resistant to scrapie. They can’t catch it. The reason is embedded in their DNA, as susceptibility for scrapie is determined by genes. A simple test reveals the polymorphism of three codons, 136, 154, and 171, which determine scrapie susceptibility. Each codon is assigned a letter. VRQ makes sheep very susceptible to scrapie, while ARR protects them from catching the disease or passing it on. For the past two decades, farmers in mainland Europe have bred their herds to contain ARR genotypes, preventing scrapie from taking hold. Once this information was available, veterinary scientists at Iceland’s Institute for Experimental Pathology at Keldur, including Stefanía .orgeirsdóttir, launched a study assessing the genes of Icelandic sheep, the only breed in the country. The results were disheartening. No ARR sheep were to be found, meaning no ARR protection could be bred into Icelandic herds. Options to fight scrapie in Iceland would continue to be limited – either import ARR sheep from other countries, and risk introducing new diseases to the isolated island breed, or a zero-tolerance approach to scrapie cases. Until now, the scorched earth approach has won out.
THE SIX SHEEP AT
SVEINSSTAÐIR THAT CARRY
THE PROMISING GENOTYPE.
A needle in a haystack
“I got a call from Karólína last spring, asking me to take samples from some sheep in my herd,” Ólafur tells me. His herd counts around 770 sheep. “I wasn’t really sure how to choose which sheep to test but I tried to cover a range of family lines,” Ólafur tells me. He took 20 samples, which were then taken to Reykjavík and to Germany to be tested. Even though T137 had been found in Stefanía’s earlier research, Gesine’s sequencing soon proved that it was rare in Iceland. From the first sample batches, no T137 cases were found. But back in Sveinsstaðir, Ólafur discovered that a couple of samples had been left behind, never making it to Germany. They got shipped with the next batch. One of the samples was from a ewe called Trú, which translates as Faith. They’d hit the jackpot. Trú carried the T137 genotype. A matriarch of a long line of ewes, further testing at the farm produced five more sheep. Tignarleg, Trygglind, Trygg, Tombóla, and Tara all carried the promising genotype. This year, lambing season starts around Easter, and the six sheep at Sveinsstaðir farm are expecting a total of 16 lambs, which will hopefully be the start of something even bigger. “We’re ecstatic. Farmers have been waiting for good news like this for the longest time,” Inga tells me with a smile. “We’re simply so grateful for this woman.” The T137 genotype still presents some issues. While the ARR genotype is internationally recognised as scrapie-resistant, much less research has been done on T137. And although six sheep were found in Sveinsstaðir, all of them are ewes, so fingers are crossed that some of the sixteen lambs this spring will be rams, ready to spread their seed across the country for a good cause. But the study wasn’t over. It still had one lucky coincidence up its sleeve.
Jackpot
When 4,200 samples had been processed over ten months, it was time for sheep from Þernunes farm in Reyðarfjörður, East Iceland. Nine sheep carrying the prized ARR genotype were discovered. This time, most of the nine were polled, in stark contrast to Ólafur’s six horned sheep.
There are more than around 400,000 sheep in Iceland. So far, a couple dozen of them have been found to carry genotypes resistant to scrapie. Finding the sheep is not a solution in and of itself, but only the first step in a massive breeding project in the years to come. Eyþór Einarsson, the sheep breeding consultant with the Agricultural Advisory Centre, tells me that the task ahead is daunting. To start with, they’ve only found one ram with a resistant genotype so far. Furthermore, that ram lives in a region where scrapie has been detected, and there are strict regulations in place limiting breeding options for such sheep. Still, the study is far from over. Farmers across the country were invited to submit samples from their own sheep and over five hundred farmers have already participated.
Breeding sheep is a complicated process and care must be taken to prevent inbreeding. But now that there is a solution in sight, the team wants to get started as soon as possible, especially following a recent surge in scrapie cases. “We want to do this as fast as we can, preferably without lowering our standards for inbreeding and without losing diversity in the breed. We haven’t faced a challenge like this before, but farmers are hopeful, and together, we’ll get this done.”
Research projects continue and enthusiastic farmers can now participate by having their sheep tested. Just before this issue of Iceland Review was sent to print, the research team had some good news. They’d discovered some sheep carrying the T137 genotype at Stóru-Hámundarstaðir farm – including another ram!
