Atypical scrapie in Australia

Cook, R W; Bingham, John; Besier, AS; Bayley, C; Hawes, M. C.; Shearer, Patrick; Yamada, Manabu; Bergfeld, Jemma; Williams, David T.; Middleton, DJ

doi:10.1111/avj.12529

Cited by 21 publications

(22 citation statements)

References 20 publications

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“…In addition to its potential role in the initial emergence of c-BSE in cattle, the presence of c-BSE prions in natural cases of AS has current and direct implications for both the continued risk of this ovine prion disease to other farmed animals and for human exposure risks. The distribution of AS cases are widespread across the world (17)(18)(19). A recent retrospective analysis of surveillance data collected over a period exceeding 10 y in the European Union (EU) concluded that the prevalence of detected AS cases has remained relatively stable in the different member states, with between 2 and 6 positive cases per 10,000 tested animals per year.…”

Section: Discussionmentioning

confidence: 99%

“…Since its original discovery in 1998 in Norway, AS has been identified in most EU member states, in Asia, and in North and South America (17). AS has also been detected in Australia and New Zealand, 2 countries that were believed to be free of animal TSEs (18,19). Retrospective studies carried out in archived animal tissues identified an AS case in a sheep that died in 1972 in the United Kingdom, demonstrating that the disease has been present in small ruminant populations for many decades (20).…”

Section: Significancementioning

confidence: 99%

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The emergence of classical BSE from atypical/Nor98 scrapie

Huor

Espinosa

Vidal

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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Atypical/Nor98 scrapie (AS) is a prion disease of small ruminants. Currently there are no efficient measures to control this form of prion disease, and, importantly, the zoonotic potential and the risk that AS might represent for other farmed animal species remains largely unknown. In this study, we investigated the capacity of AS to propagate in bovine PrP transgenic mice. Unexpectedly, the transmission of AS isolates originating from 5 different European countries to bovine PrP mice resulted in the propagation of the classical BSE (c-BSE) agent. Detection of prion seeding activity in vitro by protein misfolding cyclic amplification (PMCA) demonstrated that low levels of the c-BSE agent were present in the original AS isolates. C-BSE prion seeding activity was also detected in brain tissue of ovine PrP mice inoculated with limiting dilutions (endpoint titration) of ovine AS isolates. These results are consistent with the emergence and replication of c-BSE prions during the in vivo propagation of AS isolates in the natural host. These data also indicate that c-BSE prions, a known zonotic agent in humans, can emerge as a dominant prion strain during passage of AS between different species. These findings provide an unprecedented insight into the evolution of mammalian prion strain properties triggered by intra- and interspecies passage. From a public health perspective, the presence of c-BSE in AS isolates suggest that cattle exposure to small ruminant tissues and products could lead to new occurrences of c-BSE.

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Section: Discussionmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

The emergence of classical BSE from atypical/Nor98 scrapie

Huor

Espinosa

Vidal

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…The National Transmissible Spongiform Encephalopathy Surveillance program includes passive surveillance for scrapie by histology for any sheep that have progressive neurological signs. A report includes the neurohistological appearance of five sheep that were found to have atypical scrapie between 1999 and 2016 . Atypical scrapie appears to be a spontaneous disease that has a similar histological appearance to the commonest of the human prion diseases.…”

Section: Production Animalsmentioning

confidence: 99%

“…A report includes the neurohistological appearance of five sheep that were found to have atypical scrapie between 1999 and 2016. 3 Atypical scrapie appears to be a spontaneous disease that has a similar histological appearance to the commonest of the human prion diseases. Histological screening for scrapie focusses on the caudal brainstem and the authors note the importance of the OIE recommendations that the cerebellum also be included in any histological screening, in order to distinguish between the two types of the disease.…”

Section: Production Animalsmentioning

confidence: 99%

In this issue – December 2016

Jackson¹

2016

Aust Veterinary J

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“…Recently, cases of atypical scrapie were confirmed in both Australia and New Zealand, casting serious doubt on the validity of one of the most popular arguments used to reject the zoonotic potential of small ruminant prion diseases . More generally, active surveillance programs for TSE in small ruminants revealed how inaccurate knowledge was on the prevalence and geographical distribution of TSEs in small ruminants , and highlighted the limited value of past epidemiological studies aiming at assessing the zoonotic potential of animal TSEs.…”

Section: Zoonotic Potential Of Classical and Atypical Scrapiementioning

confidence: 99%

Animal prion diseases: the risks to human health

Houston

Andréoletti

2019

Brain Pathology

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Transmissible spongiform encephalopathies (TSEs) or prion diseases of animals notably include scrapie in small ruminants, chronic wasting disease (CWD) in cervids and classical bovine spongiform encephalopathy (C-BSE). As the transmission barrier phenomenon naturally limits the propagation of prions from one species to another, and the lack of epidemiological evidence for an association with human prion diseases, the zoonotic potential of these diseases was for a long time considered negligible. However, in 1996, C-BSE was recognized as the cause of a new human prion disease, variant Creutzfeldt-Jakob disease (vCJD), which triggered an unprecedented public health crisis in Europe. Large-scale epidemio-surveillance programs for scrapie and C-BSE that were implemented in the EU after the BSE crisis revealed that the distribution and prevalence of prion diseases in the ruminant population had previously been underestimated. They also led to the recognition of new forms of TSEs (named atypical) in cattle and small ruminants and to the recent identification of CWD in Europe. At this stage, the characterization of the strain diversity and zoonotic abilities associated with animal prion diseases remains largely incomplete. However, transmission experiments in nonhuman primates and transgenic mice expressing human PrP clearly indicate that classical scrapie, and certain forms of atypical BSE (L-BSE) or CWD may have the potential to infect humans. The remaining uncertainties about the origins and relationships between animal prion diseases emphasize the importance of the measures implemented to limit human exposure to these potentially zoonotic agents, and of continued surveillance for both animal and human prion diseases.

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Atypical scrapie in Australia

Abstract: The distinctive lesion profile of atypical scrapie in these five sheep highlights the diagnostic importance of routine histological evaluation of the cerebellum for evidence of neuropil vacuolation and associated PrP deposition in adult sheep with suspected neurological disease.

Cited by 21 publications

References 20 publications

The emergence of classical BSE from atypical/Nor98 scrapie

The emergence of classical BSE from atypical/Nor98 scrapie

In this issue – December 2016

Animal prion diseases: the risks to human health

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