Putative emergence of classical scrapie in a background of enzootic atypical scrapie.
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.
Orge
Leonor
L
Laboratório Nacional de Investigação Veterinária, Instituto Nacional de Recursos Biológicos, I. P., Portugal.
Oliveira
Ana
A
Machado
Carla
C
Lima
Carla
C
Ochoa
Cristina
C
Silva
João
J
Carvalho
Renata
R
Tavares
Paula
P
Almeida
Paula
P
Ramos
Manuel
M
Pinto
M José
MJ
Simas
J Pedro
JP
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
D011328:Prions