ProMED-mail is a program of the International Society for Infectious Diseases
Date: Thu 23 Feb 2012
Source: The Western Producer [edited]
A single case of atypical scrapie was confirmed in an Alberta sheep in January [2012].
Dr Bob Cooper, a veterinary program specialist with the Canadian Food Inspection Agency (CFIA), said the case was discovered as part of the national surveillance program to eradicate scrapie in Canada.
The surveillance program tests samples of sheep and goats for scrapie in an effort to understand where the disease is found in Canada and how to eliminate it.
Scrapie is a fatal disease that affects the central nervous system of sheep and goats. It is in the same family as BSE [bovine spongiform encephalitis] in cattle and chronic wasting disease in deer and elk.
It is a reportable disease in Canada.
Unlike classical scrapie, atypical scrapie doesn't require that sheep farms be quarantined or the flock investigated. [One wonders what evidence led authorities to develop policy that for this disease does not require a quarantine.]
Cooper said there would be some follow up to determine where the sheep lived its life, but there will be no large scale investigation or quarantine.
The atypical scrapie case was posted on the CFIA website's monthly reportable disease update [see
Canada has developed the national voluntary scrapie flock certification program in an attempt to eliminate scrapie from the national flock.
Alberta Lamb Producer chair Phil Kolodychuk was relieved the case was atypical scrapie and not classic scrapie.
"It's a bad disease. We'd like to get rid of it in our country," he said.
[Byline: Mary MacArthur]
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Communicated by: Terry S Singeltary Sr
[Scrapie is a transmissible spongiform encephalopathy (TSE), as are mad cow disease (bovine spongiform encephalopathy/BSE) and chronic wasting disease (CWD). Both BSE and scrapie have an atypical form that differs from the normal TSE seen in these animals.
In 2003, an unusual type of scrapie in sheep, named Nor98, was described in Norway [1]. Affected sheep displayed predominantly ataxia in the absence of pruritus, and neuropathological findings were mainly restricted to the cerebellar and cerebral cortices, whilst vacuolation and PrPsc accumulation in the brainstem at the level of the obex was sparse or absent. Western immunoblot analysis showed a PrPres glycoprofile with a protein band of lower molecular mass than in previous scrapie cases. Similar "atypical" scrapie cases have since been found in many other countries [2-8] and mainly in sheep of PrP genotypes not usually associated with "classical" scrapie.
References
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1. Benestad SL, Sarradin P, Thu B, et al: Cases of scrapie with
unusual features in Norway and designation of a new type, Nor98. Vet
Rec 2003; 153(7): 202-8; abstract available at
2. De Bosschere H, Roels S, Benestad SL, Vanopdenbosch E: Scrapie case
similar to Nor98 diagnosed in Belgium via active surveillance. Vet Rec
2004; 155(22): 707-8.
3. Onnasch H, Gunn HM, Bradshaw BJ, et al: Two Irish cases of scrapie
resembling Nor98. Vet Rec 2004; 155(20): 636-7.
4. Epstein V, Pointing S, Halfacre S: Atypical scrapie in the Falkland
Islands. Vet Rec 2005; 157(21): 667-8.
5. Buschmann A, Biacabe AG, Ziegler U, et al: Atypical scrapie cases
in Germany and France are identified by discrepant reaction patterns
in BSE rapid tests. J Virol Methods 2004; 117(1): 27-36; abstract
available at
6. Everest SJ, Thorne L, Barnicle DA, et al: Atypical prion protein in
sheep brain collected during the British scrapie-surveillance
programme. J Gen Virol 2006; 87(Pt 2): 471-7; available at
7. Gavier-Widen D, Noremark M, Benestad S, et al: Recognition of the
Nor98 variant of scrapie in the Swedish sheep population. J Vet Diagn
Invest 2004; 16(6): 562-7; available at
8. Orge L, Galo A, Machado C, et al: Identification of putative
atypical scrapie in sheep in Portugal. J Gen Virol 2004; 85(Pt 11):
3487-91; available at
For further information on atypical scrapie, readers are referred to ProMED-mail post 20070318.0949.
Portions of this comment were extracted from
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