title: Putative emergence of classical scrapie in a background of enzootic atypical scrapie.
abstract: Active transmissible spongiform encephalopathy (TSE) surveillance in small ruminants across Europe was implemented in 2002 following the epizootic of bovine spongiform encephalopathy. Here, we report the potential emergence of classical scrapie in Portugal, in a background of enzootic atypical scrapie. Between 2003 and 2008, 375,459 small ruminants were screened in total, with 328 animals confirmed positive for NOR98 atypical scrapie. During this period, the prevalence rate of atypical scrapie for all years combined was 0.0874% across the country. In this scenario, classical scrapie emerged as a single outbreak in 2008, with 12 identified cases. In contrast to other European countries, where classical scrapie has been enzootic for decades, these data indicate that, in Portugal, atypical scrapie is the predominant form of TSE. The findings reported here will have implications for the control of classical scrapie in Portugal, namely in terms of keeping the country free of enzootic classical scrapie.
authors.affiliation: Laboratório Nacional de Investigação Veterinária, Instituto Nacional de Recursos Biológicos, I. P., Portugal.
authors.forename: Leonor
authors.initials: L
authors.lastname: Orge
authors.forename: Ana
authors.initials: A
authors.lastname: Oliveira
authors.forename: Carla
authors.initials: C
authors.lastname: Machado
authors.forename: Carla
authors.initials: C
authors.lastname: Lima
authors.forename: Cristina
authors.initials: C
authors.lastname: Ochoa
authors.forename: João
authors.initials: J
authors.lastname: Silva
authors.forename: Renata
authors.initials: R
authors.lastname: Carvalho
authors.forename: Paula
authors.initials: P
authors.lastname: Tavares
authors.forename: Paula
authors.initials: P
authors.lastname: Almeida
authors.forename: Manuel
authors.initials: M
authors.lastname: Ramos
authors.forename: M José
authors.initials: MJ
authors.lastname: Pinto
authors.forename: J Pedro
authors.initials: JP
authors.lastname: Simas
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000473:pathology; D019353:Endemic Diseases; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D011328:Prions / Q000302:isolation & purification; D012608:Scrapie / Q000453:epidemiology*; D012756:Sheep
chemical_list: D011328:Prions