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NCBA, R-CALF, COOL, USDA (No Politics!)
Ranchers in Texas Need to Pay Close Attention to CWD TSE Prion
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<blockquote data-quote="flounder" data-source="post: 1815146" data-attributes="member: 3519"><p><p>[h4]3.2.1.2 Non-cervid domestic species[/h4]<p></p><p>The remarkably high rate of natural CWD transmission in the ongoing NA epidemics raises the question of the risk to livestock grazing on CWD-contaminated shared rangeland and subsequently developing a novel CWD-related prion disease. This issue has been investigated by transmitting CWD via experimental challenge to cattle, sheep and pigs and to tg mouse lines expressing the relevant species PrP.</p><p></p><p>For cattle challenged with CWD, PrPSc was detected in approximately 40% of intracerebrally inoculated animals (Hamir et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0079" target="_blank">2005</a>, <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0080" target="_blank">2006a</a>, <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0083" target="_blank">2007</a>). Tg mice expressing bovine PrP have also been challenged with CWD and while published studies have negative outcomes (Tamguney et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0192" target="_blank">2009b</a>), unpublished data provided for the purposes of this Opinion indicate that some transmission of individual isolates to bovinised mice is possible (Table <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-tbl-0001" target="_blank">1</a>).</p><p></p><p>In small ruminant recipients, a low rate of transmission was reported between 35 and 72 months post-infection (mpi) in ARQ/ARQ and ARQ/VRQ sheep intracerebrally challenged with mule deer CWD (Hamir et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0081" target="_blank">2006b</a>), while two out of two ARQ/ARQ sheep intracerebrally inoculated with elk CWD developed clinical disease after 28 mpi (Madsen-Bouterse et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0116" target="_blank">2016</a>). However, tg mice expressing ARQ sheep PrP were resistant (Tamguney et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0190" target="_blank">2006</a>) and tg mice expressing the VRQ PrP allele were poorly susceptible to clinical disease (Beringue et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0024" target="_blank">2012</a>; Madsen-Bouterse et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0116" target="_blank">2016</a>). In contrast, tg mice expressing VRQ sheep PrP challenged with CWD have resulted in highly efficient, life-long asymptomatic replication of these prions in the spleen tissue (Beringue et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0024" target="_blank">2012</a>).</p><p></p><p>A recent study investigated the potential for swine to serve as hosts of the CWD agent(s) by intracerebral or oral challenge of crossbred piglets (Moore et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0133" target="_blank">2016b</a>, <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0134" target="_blank">2017</a>). Pigs sacrificed at 6 mpi, approximately the age at which pigs reach market weight, were clinically healthy and negative by diagnostic tests, although low-level CWD agent replication could be detected in the CNS by bioassay in tg cervinised mice. Among pigs that were incubated for up to 73 mpi, some gave diagnostic evidence of CWD replication in the brain between 42 and 72 mpi. Importantly, this was observed also in one orally challenged pig at 64 mpi and the presence of low-level CWD replication was confirmed by mouse bioassay. The authors of this study argued that pigs can support low-level amplification of CWD prions, although the species barrier to CWD infection is relatively high and that the detection of infectivity in orally inoculated pigs with a mouse bioassay raises the possibility that naturally exposed pigs could act as a reservoir of CWD infectivity.</p><p></p><p>[h4]3.2.1.3 Other species[/h4]<p></p><p>Studies have demonstrated that the CWD agent(s) can be transmitted by the IC route in several species of rodents, such as voles (Subfamily Arvicolinae), deer mice (<em>Peromyscus maniculatus</em>), mice and hamsters (Subfamily Cricetinae). The susceptibility was, however, variable, being high in voles and deer mice but lower in mice and hamsters (Raymond et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0162" target="_blank">2007</a>; Heisey et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0086" target="_blank">2010</a>; Kurt et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0104" target="_blank">2011</a>; Di et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0054" target="_blank">2013</a>; Lee et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0111" target="_blank">2013</a>). Mink (subfamily Mustelinae) (Harrington et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0085" target="_blank">2008</a>), ferrets (<em>Mustela putorius</em>) (Bartz et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0011" target="_blank">1998</a>; Sigurdson et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0181" target="_blank">2008</a>) and cats (Mathiason et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0120" target="_blank">2013</a>) were susceptible to IC challenge with NA CWD sources, while CWD transmitted poorly to raccoons (<em>Procyon lotor</em>) by the IC route (Moore et al., <a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0136" target="_blank">2019</a>).</p><p></p><p>[h4]3.2.2 European isolates[/h4]<p></p><p><a href="https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863" target="_blank">https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863</a></p><p></p><p>CWD is highly infectious and very resistant to weather conditions and traditional disinfectants so it can remain in the environment for a long time. CWD can stick to soil particles for up to 10 years.</p><p></p><p>The only way to rapidly inactivate CWD's infectious agent is to soak clothes or equipment in a solution of bleach that has 20,000 parts per million of active chlorine, or 2 molar sodium hydroxide solution, for one hour.</p><p></p><p>This treatment will damage or destroy most clothing, footwear and hunting equipment.</p><p></p><p><a href="https://www.gov.uk/guidance/chronic-wasting-disease" target="_blank">https://www.gov.uk/guidance/chronic-wasting-disease</a></p><p></p><p>terry</p></blockquote><p></p>
[QUOTE="flounder, post: 1815146, member: 3519"] [H4]3.2.1.2 Non-cervid domestic species[/H4] The remarkably high rate of natural CWD transmission in the ongoing NA epidemics raises the question of the risk to livestock grazing on CWD-contaminated shared rangeland and subsequently developing a novel CWD-related prion disease. This issue has been investigated by transmitting CWD via experimental challenge to cattle, sheep and pigs and to tg mouse lines expressing the relevant species PrP. For cattle challenged with CWD, PrPSc was detected in approximately 40% of intracerebrally inoculated animals (Hamir et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0079']2005[/URL], [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0080']2006a[/URL], [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0083']2007[/URL]). Tg mice expressing bovine PrP have also been challenged with CWD and while published studies have negative outcomes (Tamguney et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0192']2009b[/URL]), unpublished data provided for the purposes of this Opinion indicate that some transmission of individual isolates to bovinised mice is possible (Table [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-tbl-0001']1[/URL]). In small ruminant recipients, a low rate of transmission was reported between 35 and 72 months post-infection (mpi) in ARQ/ARQ and ARQ/VRQ sheep intracerebrally challenged with mule deer CWD (Hamir et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0081']2006b[/URL]), while two out of two ARQ/ARQ sheep intracerebrally inoculated with elk CWD developed clinical disease after 28 mpi (Madsen-Bouterse et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0116']2016[/URL]). However, tg mice expressing ARQ sheep PrP were resistant (Tamguney et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0190']2006[/URL]) and tg mice expressing the VRQ PrP allele were poorly susceptible to clinical disease (Beringue et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0024']2012[/URL]; Madsen-Bouterse et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0116']2016[/URL]). In contrast, tg mice expressing VRQ sheep PrP challenged with CWD have resulted in highly efficient, life-long asymptomatic replication of these prions in the spleen tissue (Beringue et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0024']2012[/URL]). A recent study investigated the potential for swine to serve as hosts of the CWD agent(s) by intracerebral or oral challenge of crossbred piglets (Moore et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0133']2016b[/URL], [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0134']2017[/URL]). Pigs sacrificed at 6 mpi, approximately the age at which pigs reach market weight, were clinically healthy and negative by diagnostic tests, although low-level CWD agent replication could be detected in the CNS by bioassay in tg cervinised mice. Among pigs that were incubated for up to 73 mpi, some gave diagnostic evidence of CWD replication in the brain between 42 and 72 mpi. Importantly, this was observed also in one orally challenged pig at 64 mpi and the presence of low-level CWD replication was confirmed by mouse bioassay. The authors of this study argued that pigs can support low-level amplification of CWD prions, although the species barrier to CWD infection is relatively high and that the detection of infectivity in orally inoculated pigs with a mouse bioassay raises the possibility that naturally exposed pigs could act as a reservoir of CWD infectivity. [H4]3.2.1.3 Other species[/H4] Studies have demonstrated that the CWD agent(s) can be transmitted by the IC route in several species of rodents, such as voles (Subfamily Arvicolinae), deer mice ([I]Peromyscus maniculatus[/I]), mice and hamsters (Subfamily Cricetinae). The susceptibility was, however, variable, being high in voles and deer mice but lower in mice and hamsters (Raymond et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0162']2007[/URL]; Heisey et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0086']2010[/URL]; Kurt et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0104']2011[/URL]; Di et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0054']2013[/URL]; Lee et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0111']2013[/URL]). Mink (subfamily Mustelinae) (Harrington et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0085']2008[/URL]), ferrets ([I]Mustela putorius[/I]) (Bartz et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0011']1998[/URL]; Sigurdson et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0181']2008[/URL]) and cats (Mathiason et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0120']2013[/URL]) were susceptible to IC challenge with NA CWD sources, while CWD transmitted poorly to raccoons ([I]Procyon lotor[/I]) by the IC route (Moore et al., [URL='https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863#efs25863-bib-0136']2019[/URL]). [H4]3.2.2 European isolates[/H4] [URL]https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2019.5863[/URL] CWD is highly infectious and very resistant to weather conditions and traditional disinfectants so it can remain in the environment for a long time. CWD can stick to soil particles for up to 10 years. The only way to rapidly inactivate CWD's infectious agent is to soak clothes or equipment in a solution of bleach that has 20,000 parts per million of active chlorine, or 2 molar sodium hydroxide solution, for one hour. This treatment will damage or destroy most clothing, footwear and hunting equipment. [URL]https://www.gov.uk/guidance/chronic-wasting-disease[/URL] terry [/QUOTE]
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