Atypical/Nor98 scrapie in the Basque Country: a case report of eight outbreaks

Rodríguez-Martínez, Ana B.; Garrido, Joseba M.; Maza, Sonia; Benedicto, Leyre; Geijó, Mariví; Gómez, Nieves; Minguijón, E.; Benestad, Sylvie L.; Juste, Ramón A.

doi:10.1186/1746-6148-6-17

Cited by 7 publications

(4 citation statements)

References 58 publications

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“…While CS appears clustered at flock level (McIntyre et al., 2008b ) and with a heterogeneous presentation across countries and surveillance streams (Del Rio Vilas et al., 2007 ), the presentation of AS is typical of a rare disease with prevalence estimates remarkably homogeneous across countries, surveillance streams and calendar years of surveillance in the EU (Fediaevsky et al., 2008 ). When detected, AS usually appears in a single sheep per affected flock (De Bosschere et al., 2004 ; Moum et al., 2005 ; Rodríguez‐Martínez et al., 2010 ), with some exceptions. In an analysis of the prevalence of AS in 11 European countries, it was concluded that AS is not contagious, or has a very low transmissibility under natural conditions compared with CS (Fediaevsky et al., 2010 ).…”

Section: Assessmentmentioning

confidence: 99%

Scientific report on the analysis of the 2‐year compulsory intensified monitoring of atypical scrapie

Arnold¹,

Ru²,

Simmons³

et al. 2021

EFS2

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The European Commission asked EFSA whether the scientific data on the 2-year intensified monitoring in atypical scrapie (AS) outbreaks (2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020) provide any evidence on the contagiousness of AS, and whether they added any new knowledge on the epidemiology of AS. An ad hoc data set from intensified monitoring in 22 countries with index case/s of AS in sheep and/or goats (742 flocks from 20 countries, 76 herds from 11 countries) was analysed. No secondary cases were confirmed in goat herds, while 35 secondary cases were confirmed in 28 sheep flocks from eight countries. The results of the calculated design prevalence and of a model simulation indicated that the intensified monitoring had limited ability to detect AS, with no difference between countries with or without secondary cases. A regression model showed an increased, but not statistically significant, prevalence (adjusted by surveillance stream) of secondary cases in infected flocks compared with that of index cases in the non-infected flocks (general population). A simulation model of within-flock transmission, comparing a contagious (i.e. transmissible between animals under natural conditions) with a non-contagious scenario, produced a better fit of the observed data with the non-contagious scenario, in which each sheep in a flock had the same probability of developing AS in the first year of life. Based on the analyses performed, and considering uncertainties and data limitations, it was concluded that there is no new evidence that AS can be transmitted between animals under natural conditions, and it is considered more likely (subjective probability range 50-66%) that AS is a non-contagious, rather than a contagious disease. The analysis of the data of the EU intensified monitoring in atypical scrapie infected flocks/herds confirmed some of the known epidemiological features of AS but identified that major knowledge gaps still remain.

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Section: Assessmentmentioning

confidence: 99%

Scientific report on the analysis of the 2‐year compulsory intensified monitoring of atypical scrapie

Arnold¹,

Ru²,

Simmons³

et al. 2021

EFS2

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“…There is also evidence of a certain degree of diversity in the neuroanatomic distribution of PrP d and histopathologic lesions among individual sheep, as well as between sheep and goats (Fig. 1C-F) when whole brains are examined 16,130,143,150,186 . Whether such differences are related to host factors (e.g., the PrP genotype and route of transmission) or to different strains of the agent is currently under investigation.…”

Section: Atypical Scrapie a Newly Identified Tse In Small Ruminantsmentioning

confidence: 99%

“…1C-F) when whole brains are examined. 16,130,143,150,186 Whether such differences are related to host factors (e.g., the PrP genotype and route of transmission) or to different strains of the agent is currently under investigation. By reviewing the available data, preliminary diagnostic criteria to discriminate atypical scrapie from small ruminant BSE and classical scrapie were defined in an opinion of the European Food Safety Authority, Biohazard Panel (Table 2).…”

Section: 163mentioning

confidence: 99%

Atypical Transmissible Spongiform Encephalopathies in Ruminants: A Challenge for Disease Surveillance and Control

2010

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Abstract. Since 1987, when bovine spongiform encephalopathy (BSE) emerged as a novel disease in cattle, enormous efforts were undertaken to monitor and control the disease in ruminants worldwide. The driving force was its high economic impact, which resulted from trade restrictions and the loss of consumer confidence in beef products, the latter because BSE turned out to be a fatal zoonosis, causing variant Creutzfeldt-Jakob disease in human beings. The ban on meat and bone meal in livestock feed and the removal of specified risk materials from the food chain were the main measures to successfully prevent infection in cattle and to protect human beings from BSE exposure. However, although BSE is now under control, previously unknown, socalled atypical transmissible spongiform encephalopathies (TSEs) in cattle and small ruminants have been identified by enhanced disease surveillance. This report briefly reviews and summarizes the current level of knowledge on the spectrum of TSEs in cattle and small ruminants and addresses the question of the extent to which such atypical TSEs have an effect on disease surveillance and control strategies.

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“…4,39 The majority of atypical scrapie/Nor98 cases have been identified in clinically normal sheep sampled at slaughter. 4,[12][13][14]21 Cases have been reported from Norway, Sweden, Finland, the United Kingdom, Germany, France, Portugal, Belgium, The Netherlands, Ireland, Denmark, 15 Spain, 34 the United States, 25 and Canada. 28 Retrospective testing of archived tissues has shown that atypical scrapie/ Nor98 has existed in the United Kingdom at least since 1987.…”

Section: Introductionmentioning

confidence: 99%

Atypical Scrapie/Nor98 in a Sheep from New Zealand

et al. 2010

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Abstract. In a consignment of sheep brains from New Zealand, to be used in Europe as negative control material in scrapie rapid screening test evaluations, brain samples from 1 sheep (no. 1512) gave the following initially confusing results in various screening tests: the brainstem repeatedly produced negative results in 2 very similar screening kits (enzyme-linked immunosorbent assay [ELISA]-1, ELISA-2), a macerate made from brainstem and cerebellum returned a clearly positive result in ELISA-2, and the macerate and a brainstem sample gave negative results in a third screening test (ELISA-3). In subsequent testing, cerebellum tissue alone tested strongly positive in ELISA-1 and produced a banding pattern very similar to atypical scrapie/Nor98 in a confirmatory Western blot (WB). The macerate showed weak staining in the confirmatory WB but presented a staining pattern identical to atypical scrapie/Nor98 in the scrapie-associated fibril WB. The latter test confirmed conclusively the first case of atypical scrapie/Nor98 in a sheep from New Zealand. Other parts of the brain either tested negative or very weak positive in ELISA-2 and in WBs, or tested with negative results by histopathology and immunohistochemistry. It appears that sheep no. 1512 is a case of atypical scrapie/ Nor98 in which the abnormal prion protein was detected mainly in the cerebellum. This case emphasizes the need to retain brainstem, and cerebral and cerebellar tissues, as frozen and fixed materials, for conclusive confirmatory testing. Furthermore, consideration should be given to which screening method to use.

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Atypical/Nor98 scrapie in the Basque Country: a case report of eight outbreaks

Cited by 7 publications

References 58 publications

Scientific report on the analysis of the 2‐year compulsory intensified monitoring of atypical scrapie

Scientific report on the analysis of the 2‐year compulsory intensified monitoring of atypical scrapie

Atypical Transmissible Spongiform Encephalopathies in Ruminants: A Challenge for Disease Surveillance and Control

Atypical Scrapie/Nor98 in a Sheep from New Zealand

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