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Research theme : Prion diseases

Maladies à prions- vache atteinte d' ESB

Prion diseases or transmissible spongiform encephalopathies (TSEs) are slow, lethal transmissible neurodegenerative diseases, affecting both humans (Creutzfeldt-Jakob disease; CJD) and animals, including sheep and goats (scrapie and atypical TSEs), deer and elk (chronic wasting disease; CWD), mink (transmissible mink encephalopathy ; TME) felidae (feline spongiform encephalopathy; FSE) and cattle (bovine spongiform encephalopathy; BSE).

 

The exact nature of the infectious agent remains controversial. These diseases are associated with the accumulation in infected tissues of a disease-associated form of a host-encoded protein, the prion protein (PrP).

 

Contrary to the normal form of the protein, this form of PrP is partially resistant to protease digestion (PrPres). The properties of the different TSE agents were demonstrated to be very stable after transmission to a variety of different species.

 

Molecular studies of PrPres, followed by transmission studies to mice, gave the evidence for the transmission of the BSE agent to humans where it induced a variant form of the fatal CJD (208 cases of vCJD until 2009) and also to different animal species including a goat in France.

Prion diseases

 

These methods led to the discovery of deviant BSE forms in a few affected cattle in Europe and the United States. Two atypical BSE strains are described, namely the H and the L type. The H type could also be linked to the cases of TSE in mink (TME). Considerable numbers of new TSE forms in small ruminants, referred to as "atypical scrapie" or "Nor98", have meanwhile been identified in most European countries.

 

The transmissibility of the agent of Bovine Spongiform Encephalopathy (BSE) to man, causing vCJD, is now generally accepted but the extent of a possible future epidemic in man can not yet be defined at present. However, the incidence of vCJD in the UK appears now to be decreasing after an exponential increase since 1997.

Unfortunately, in recent years the first cases of vCD due to transfusion of blood or blood products from asymptomatic donors have been observed, so a second vCJD wave cannot be excluded, especially in the absence of in vivo tests.

 

  

Since the first cases of BSE were described in the UK in 1987 more than 183.000 BSE cases are confirmed in the UK, representing about 98% of all BSE cases in the world. The evolution of the epidemic in the UK was as follows:

 

 

 

At present 224 vCJD cases (Creutzfeldt-Jacob disease) are confirmed.

 

creutzfeld 2012

 

 Since the first cases of BSE were described in the UK in 1987 more than 183.000 BSE cases are confirmed in the UK, representing about 98% of all BSE cases in the world. The evolution of the epidemic in the EU was as follows:

( source : DG Sanco)

 

BSE cases in 2012

 

Ces dernières années, les cas découverts de ESB sont principalement des cas atypiques. Vous voyez dans le graphique suivant la proportion ( ratio) entre les cas classiques et atypiques au courant des années:

 

Ratio classical BSE

 

 

Références

• BSE en variant CJZ: nieuwe inzichten en achtergrondinformatie. (2000)
(Vanopdenbosch E, Roels S) Vlaams Diergeneeskundig Tijdschrift 69, 371-376.

• Encephalopathie spongiforme bovine et variante de la maladie de Creutzfeldt-Jakob : quelques informations concernant l'origine, le diagnostic, l'épidemiologie, l'analyse du risque et l'avenir (2001). (Roels S, De Meyer G & Vanopdenbosch E) Annales de Médecine Vétérinaire 145, 333-341.

• Le diagnostic immunologique rapide des encephalopathies spongiformes transmissibles. (2001) (Pastoret P.P., Gouffaux M., Saegerman C., Roels S., Dechamps P., Thiry E., Vanopdenbosch E.) Annales de Médecine Vétérinaire 145, 164-173.

• Variation of mass (volume) taken with the calibrated syringe and of the results provided by the Platelia BSE test (BIORAD) upon storage of brain stem samples at - 20°C. (2002) (Roels S, De Meyer G, Tedik K, Foubert R & Vanopdenbosch E) Animal Research 51, 493-499.

• First results of chronic wasting disease (CWD) surveillance in the South-Eastern part of Belgium (2005) (Roels S, Saegerman C, De Bosschere H, Berkvens D, Gregoire F, Hoyoux A, Mousset B, Desmecht D, Vanopdenbosch E and Linden A.) Veterinary Quarterly 27 (3), 98-104.

• First chronic wasting disease (CWD) surveillance of roe deer (Capreolus capreolus) in the Northern part of Belgium (2006)(De Bosschere H., Saegerman C., Neukermans A., Berkvens D., Casaer J., Vanopdenbosch E. and Roels S.) Veterinary Quarterly 28 (2), 54-60.

• Classification of Sporadic Creutzfeldt-Jakob Disease Based on Clinical and Neuropathological Characteristics. (2007) (Cortiñas Abrahantes J, Aerts M, van Everbroeck B, Saegerman S, Berkvens D, Geys H, Mintiens K, Roels S and Cras P) European Journal of Epidemiology 22, 457-465.

• Risk assessment of laboratories involving the manipulation of unconventional agents causing TSE (2009) (Leunda-Casi A, Pauwels K, Herman Hh, Verheust C, Zorzi W, Thellin O, Roels S , Van Vaerenbergh B) The Belgian Biosafety Server,
http://www.biosafety.be/CU/PDF/Report_Prions_IPH_D_2009_2505_49.pdf

• Sampling quality for BSE routine monitoring in Belgium (2013) (Dobly A, Van der Heyden S, Di Silvestro F, Roels S) Vet Archives, 83(3), 341-346.