TITLE

Comparison of strategies for substantiating freedom from scrapie in a sheep flock

AUTHOR(S)
Durand, Benoit; Martinez, Marie-José; Calavas, Didier; Ducrot, Christian
PUB. DATE
January 2009
SOURCE
BMC Veterinary Research;2009, Vol. 5, p1
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Background: The public health threat represented by a potential circulation of bovine spongiform encephalopathy agent in sheep population has led European animal health authorities to launch large screening and genetic selection programmes. If demonstrated, such a circulation would have dramatic economic consequences for sheep breeding sector. In this context, it is important to evaluate the feasibility of qualification procedures that would allow sheep breeders demonstrating their flock is free from scrapie. Classical approaches, based on surveys designed to detect disease presence, do not account for scrapie specificities: the genetic variations of susceptibility and the absence of live diagnostic test routinely available. Adapting these approaches leads to a paradoxical situation in which a greater amount of testing is needed to substantiate disease freedom in genetically resistant flocks than in susceptible flocks, whereas probability of disease freedom is a priori higher in the former than in the latter. The goal of this study was to propose, evaluate and compare several qualification strategies for demonstrating a flock is free from scrapie. Results: A probabilistic framework was defined that accounts for scrapie specificities and allows solving the preceding paradox. Six qualification strategies were defined that combine genotyping data, diagnostic tests results and flock pedigree. These were compared in two types of simulated flocks: resistant and susceptible flocks. Two strategies allowed demonstrating disease freedom in several years, for the majority of simulated flocks: a strategy in which all the flock animals are genotyped, and a strategy in which only founders animals are genotyped, the flock pedigree being known. In both cases, diagnostic tests are performed on culled animals. The less costly strategy varied according to the genetic context (resistant or susceptible) and to the relative costs of a genotyping exam and of a diagnostic test. Conclusion: This work demonstrates that combining data sources allows substantiating a flock is free from scrapie within a reasonable time frame. Qualification schemes could thus be a useful tool for voluntary or mandatory scrapie control programmes. However, there is no general strategy that would always minimize the costs and choice of the strategy should be adapted to local genetic conditions.
ACCESSION #
42094592

 

Related Articles

  • Subclinical Scrapie Infection in a Resistant Species: Persistence, Replication, and Adaptation of Infectivity during Four Passages. Race, Richard; Meade-White, Kimberley; Raines, Anne; Raymond, Gregory J.; Caughey, Byron; Chesebro, Bruce // Journal of Infectious Diseases;12/2/2002 Supplement, Vol. 186, pS166 

    Cross-species infection with transmissible spongiform encephalopathy agents may lead to subclinical infection and to adaptation of the infection to new species. This is of particular concern for the millions of people possibly exposed to bovine spongiform encephalopathy (BSE) by consumption of...

  • Prion diseases: BSE in sheep bred for resistance to infection. Houston, Fiona; Goldmann, Wilfred; Chong, Angela; Jeffrey, Martin; Gonzalez, Lorenzo; Foster, James; Parnham, David; Hunter, Nora // Nature;5/29/2003, Vol. 423 Issue 6939, p498 

    Selective breeding for disease-resistant genotypes is being pursued as a means of eradicating scrapie (and bovine spongiform encephalopathy (BSE), if it is present) from sheep flocks. Here we show that the genotype associated with the highest resistance can still be infected with BSE by...

  • Sorry, the mutton's off. Pearce, Fred // New Scientist;09/13/97, Vol. 155 Issue 2099, p22 

    Focuses on the calls made by scientists specializing in spongiform encephalopathies on the need for action against scrapie in Great Britain. Link between scrapie and Creutzfeld-Jakob disease; Possible presence of bovine spongiform encephalopathy; British government's banning of the sale of...

  • Food. Green, Emily // New Statesman;03/13/98, Vol. 127 Issue 4376, p39 

    Reports about the events on the opening day of the inquiry of Lord Justice Phillips into bovine spongiform encephalopathy (BSE). Functions of the inquiry press office; News regarding the restrictions on food caused by the outbreak of scrapie, the spongy-disease in cattle; Details about the...

  • The eyes have it. Knight, Jonathan // New Scientist;04/25/98, Vol. 158 Issue 2131, p6 

    Announces a simple test for scrapie. Procedures of the test; Research on the validity of test results; Hopes for a similar test for bovine spongiform encephalopathy (BSE).

  • Doubts over ability to monitor risks of BSE spread to sheep. Butler, Declan // Nature;9/3/1998, Vol. 395 Issue 6697, p6 

    Discusses the possibility that bovine spongiform encephalopathy (BSE) may have spread to sheep and goats in Great Britain and Europe. How the animals may have been infected; Similarities between BSE and scrapie in these animals; Recommendations by the Spongiform Encephalopathy Advisory...

  • 'BSE controls working' in case of dead Carmarthenshire cow. White, Kevin // Grocer;10/10/2015, p46 

    The article reports on the confirmation by the British Department for Environment, Food and Rural Affairs (DEFRA) that a case of bovine spongiform encephalopathy (BSE) identified in the first week of October 2015 by the Welsh government originated on a farm in Carmarthenshire.

  • How transmissible is mad cow disease?  // CMAJ: Canadian Medical Association Journal;10/01/97, Vol. 157 Issue 7, p866 

    Refers to a study in `Nature' magazine regarding the transmission of bovine spongiform encephalopathy and scrapie to humans.

  • How Now, Mad Cow? Halweil, Brian; Nierenberg, Dani // Chain Reaction;Fall2001, Issue 85, p04 

    Argues that globalization, economics and poor animal husbandry are responsible for the spread of animal-borne epidemics. Background on the mad cow disease in Great Britain and the United States; Overview of the globalized trade in food and services; Why modern animal farm facilitated the...

Share

Read the Article

Courtesy of VIRGINIA BEACH PUBLIC LIBRARY AND SYSTEM

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics