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Estimation of Epidemic Size and Incubation Time Based on Age Characteristics of vCJD in the United Kingdom

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The size of the variant Creutzfeldt-Jakob Disease (vCJD) epidemic in the United Kingdom is a major public health concern and a subject of speculation. The cases are young (mean age = 28). Assuming that the risk of developing the disease in susceptible exposed subjects decreases exponentially with age after age 15, that all infections occurred between 1980 and 1989, and that the distribution of the incubation period is lognormal, we estimate that the mean duration of the incubation period is 16.7 years [95% confidence interval (CI): 12.4 to 23.2] and that the total number of cases will be 205 (upper limit of the 95% CI: 403).
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... Elle peut aussi se transmettre à d'autres animaux comme les grands félins ou les chats domestiques (encéphalopathie spongiforme féline (ESF)) (Valleron et al., 2001) Une grande épidémie d'ESB a eu lieu au Royaume Uni entrainant l'abattage d'environ 1 million de bovins et la mort d'environ 150 patients infectés (Prusiner., 1997 ;Andrews et al., 2003). ...
... ntation animal et des abas de bovin dans la chaine alimentaire, l'inscription de l'ESB dans les maladies à déclaration obligatoire, la mise en place de surveillance active et l'abattage systématique des troupeaux infectés, l'interdiction de la consommation des tissus les plus infectieux comme le cerveau, la moelle épinière, le thymus et l'intestin.(Valleron et al., 2001). ...
Thesis
Les prions résultent d’un changement de conformation de la protéine PrP et sont responsables de maladies neurodégénératives fatales et transmissibles, chez l’homme et l’animal. Sous sa forme prion, la PrP devient insoluble, résistante aux protéases et forme des agrégats riches en feuillet bêta. Les prions convertissent la PrP cellulaire normale en un élément du prion par simple contact, se multipliant ainsi dans le cerveau. Nous montrons qu’une délétion raccourcissant l’hélice H2 de la PrP ovine réduit la stabilité de la protéine et induit sa conversion spontanée en un nouveau type de príon dans un modèle de culture cellulaire. Ce nouveau príon est capable de convertir la PrP mutante mais aussi son fragment C1. Le C1 est une forme raccourcie de la PrP, tronquée en NKterminal par les métalloprotéases, mais est présent avec la PrP entière à la surface cellulaire. Le fragment C1 n’est pas converti par les souches classiques de prion et est considéré comme trop court pour former un prion. Nous montrons au contraire que le C1 de la PrP mutée peut adopter une structure prion autoKréplicative, résistante aux protéases et infectieuse. De plus, les fibres amyloïdes produites in& vitro avec une PrP recombinante présentant la même délétion se sont comportées comme des prions synthétiques, induisant la conversion en prion de la PrP cellulaire homologue et de son fragment C1. L’analyse des fibres par RMN du solide a montré un changement de conformation de la région CK terminale vers une forme enrichie en feuillet bêta.
... During the 1980s the UK human population is estimated to have been extensively exposed to bovine spongiform encephalopathy (BSE) prions via contaminated food (Wilesmith, 1993;Valleron et al., 2001). Despite this widespread risk of zoonotic disease transmission, the numbers of definite and probable human cases of variant Creutzfeldt-Jakob disease (vCJD) due to the consumption of BSE-contaminated food have remained low (n = 178, March 2022), with no new cases recorded since 2016 (Unit, 2018). ...
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... Si l'on analyse les cas d'ESB par rapport à leur année de naissance (Fig. 1, 2 et 3) on constate que la contamination du cheptel britannique suit une courbe exponentielle Lorsque, en mars 1996, on sut que l'ESB pouvait être transmise à l'Homme, là encore le consommateur a été inquiet face aux prévisions alarmistes des épidémiologistes qui essayaient d'évaluer le risque potentiel pour la santé publique, mais, qui se fondaient sur des données limitées (d'où certains intervalles de confiance présentant une zone d'incertitude de quelques cas à des millions de personnes contaminées par l'agent bovin). Ce n'est que 5 ans plus tard qu'il leur fut possible d'être plus précis, notamment grâce aux travaux de d'Alain-Jacques Valleron en 2001 annonçant 205 cas humains de variants de la MCJ (vMCJ) avec 16,5 ans d'incubation [10]. ...
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Résumé Le concept « une seule santé » lie étroitement la santé humaine et la santé animale car de nombreuses maladies sont des zoonoses. Les exemples historiques témoignant d’une collaboration efficace entre la médecine vétérinaire et la médecine humaine sont nombreux dans la mise au point des premiers vaccins utilisés dans le monde (variole, rage, tétanos, diphtérie, tuberculose, etc.). Mais lorsqu’une maladie nouvelle apparaît chez l’animal, le risque d’une transmission possible à l’Homme est difficile à estimer. Dans ce dernier cas, la perte de confiance du consommateur face aux incertitudes scientifiques peut provoquer une crise sanitaire (exemples de l’encéphalopathie spongiforme bovine et de la peste aviaire H5N1). Mais la plus grave crise que nous connaissons depuis le début de l’année 2020 est celle de la pandémie de Covid-19 qui confirme que la modification des écosystèmes de certaines espèces sauvages comme la chauve-souris fer à cheval peut avoir des conséquences importantes pour la santé publique. Les animaux ayant été malades de la Covid-19 ont été contaminés par l’Homme mais on ne peut pas exclure actuellement le risque de réservoir animal pour le SARS-CoV-2 qui a circulé dans le monde entier.
... Figure 2 shows that the incubation periods between transfusion and the onset of clinical symptoms varied from 6.5 to 8.5 years. This is broadly in line with incubation period for vCJD estimated from the lag between the peaks of the BSE and vCJD epidemics [100][101][102]. Shown as well is the time interval between the donation of blood and the onset of symptoms in the donor ( Figure 2). ...
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