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Mar 25th, 2012
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Rapid recontamination of a farm building occurs after attempted prion removal #7397872 01/07/19 05:26 PM
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flounder Offline OP
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i know some here (mostly the same few), don't want to hear this, don't want to read it, and don't want you to read it either.

EDUCATE YOURSELVES HUNTERS!


Rapid recontamination of a farm building occurs after attempted prion removal

http://dx.doi.org/10.1136/vr.105054

Kevin Christopher Gough, BSc (Hons), PhD1, Claire Alison Baker, BSc (Hons)2, Steve Hawkins, MIBiol3, Hugh Simmons, BVSc, MRCVS, MBA, MA3, Timm Konold, DrMedVet, PhD, MRCVS3 and Ben Charles Maddison, BSc (Hons), PhD2

Author affiliations

School of Veterinary Medicine and Science, The University of Nottingham, Loughborough, UK ADAS, School of Veterinary Medicine and Science, The University of Nottingham, Loughborough, UK Animal Sciences Unit, Pathology Department, Animal & Plant Health Agency Weybridge, New Haw, Addlestone, Surrey, UK E-mail for correspondence; ben.maddison@adas.co.uk

Abstract

The transmissible spongiform encephalopathy scrapie of sheep/goats and chronic wasting disease of cervids are associated with environmental reservoirs of infectivity.

Preventing environmental prions acting as a source of infectivity to healthy animals is of major concern to farms that have had outbreaks of scrapie and also to the health management of wild and farmed cervids.

Here, an efficient scrapie decontamination protocol was applied to a farm with high levels of environmental contamination with the scrapie agent.

Post-decontamination, no prion material was detected within samples taken from the farm buildings as determined using a sensitive in vitro replication assay (sPMCA).

A bioassay consisting of 25 newborn lambs of highly susceptible prion protein genotype VRQ/VRQ introduced into this decontaminated barn was carried out in addition to sampling and analysis of dust samples that were collected during the bioassay.

Twenty-four of the animals examined by immunohistochemical analysis of lymphatic tissues were scrapie-positive during the bioassay, samples of dust collected within the barn were positive by month 3.

The data illustrates the difficulty in decontaminating farm buildings from scrapie, and demonstrates the likely contribution of farm dust to the recontamination of these environments to levels that are capable of causing disease.

snip...

PrPC is ubiquitous in its distribution in vivo2 and with both scrapie and CWD the in vivo dissemination of infectivity is also widespread with PrPSc usually accumulating within peripheral lymphatic tissues before the CNS.3 4 With scrapie, PrPSc can be secreted/ excreted via a multiplicity of routes including saliva,5 6 milk,7 faeces,8 skin9 and urine.10 The accumulation of this material within the environment (particularly the built farm environment),11 12 creates levels of infectivity that can be transmitted to naÔve animals. These reservoirs of infectivity can remain infectious for prolonged periods of time, in one such recorded incident at least 16 years.13 The advent of high sensitivity prion replication assays such as protein misfolding cyclic amplification (PMCA) with application to sheep/goat scrapie14 15 has allowed the monitoring of prions within environments.11

Attempts to decontaminate pens on a scrapie-affected farm and measuring efficacy using a sheep bioassay were previously reported.12 It was concluded that the failure of effective decontamination within that study was likely to have been due to the incomplete farm decontamination and the presence of dust containing infectious prions that recontaminated the pen surfaces. The serial protein misfolding cyclic amplification (sPMCA) technique was recently used to confirm the presence of prions within extracts prepared from dust samples that had settled on sterile surfaces.16 Given the presence of mobile infectious prions within dust, it was proposed that for effective scrapie decontamination emphasis should be given to the removal of all sources of dust within the decontamination strategy for a farm. More recently, the sPMCA technique has been used by the authors' laboratory to look at effective methods of decontaminating prions bound to concrete surfaces within the laboratory setting.17 This study demonstrated that current methodology based on a one-hour exposure to 20000 ppm free chlorine was likely to be ineffective at removing surface-bound scrapie prion. However, there was an enhanced effectiveness of this chemical decontamination when using multiple applications over four hours. Here, a study is described where a scrapie-affected farm was decontaminated using four applications of 20000 ppm free chlorine to livestock barns and concreted areas. The decontamination also included a high-level clean of the buildings that had housed sheep to remove all traces of dust as far as practicable before the chemical decontamination procedure. Following these treatments the surfaces within the barn were demonstrably free from prion using a sensitive sPMCA assay. The presence of any residual infectivity was then evaluated by sheep bioassay and dust samples collected during the bioassay were assayed for prion seeding activity by sPMCA.

snip...

Discussion

The authors' previous work on this farm indicated that dust harbours low levels of mobile scrapie prions that can accumulate on surfaces16 and this is likely to perpetuate transmission of scrapie within such a farm environment.12 In addition, previous in vitro modelling of scrapie prions bound to a concrete Ďfomiteí demonstrated that prion seeding activity could be inactivated by four applications of 20,000 ppm free chlorine as measured by a sPMCA assay. This previous modelling demonstrated that residual contamination of the swab extract with hypochlorite at levels which would inhibit the sPMCA are unlikely, and the authors consider these results as reduction in seeding titre.17 Here, this same decontamination methodology was tested within a farm-scale study which also included steps to remove dust within the barns. This study demonstrated that this thorough decontamination method applied to a farm with a high incidence of naturally acquired scrapie was sufficient to remove scrapie prions on surfaces to levels that were undetectable by sPMCA, one of the most sensitive biochemical assays for prions. The authors' sPMCA assay has an limit of detection of around 1Ė10pg scrapie-infected sheep brain per sPMCA reaction. The authors assume that the samples negative by sPMCA had less than this amount (of brain equivalent) within the extracts that were prepared. This treatment together with measures designed to minimise the amount of dust retained within the buildings (vacuuming all surfaces, pressure washing and then hypochlorite treatment) was expected to have removed all infectivity from the buildings and the concrete areas surrounding them, and it was anticipated that the sheep bioassay would confirm absence of infective prion.

However, the introduction into this decontaminated barn of 25 VRQ/VRQ sheep (a genotype highly susceptible to classical scrapie) demonstrated that all animals, with the exception of 1 lamb that died at 122 dpe, had detectable PrPSc in lymphoid tissue, indicating infection with the scrapie agent. This included 14 animals (54 per cent) that were PrPSc-positive on the first RAMALT analysis at 372 dpe or 419 dpe. Although infected sheep were removed based on a positive RAMALT result, it is possible that lateral transmission or subsequent contamination of the environment from infected sheep had contributed to the rapid spread of scrapie in nearly all sheep. It has been shown previously that objects in contact with scrapie-infected sheep, such as water troughs and fence posts, can act as a reservoir for infection.23 As in the authors' previous study,12 the decontamination of this sheep barn was not effective at removing scrapie infectivity, and despite the extra measures brought into this study (more effective chemical treatment and removal of sources of dust) the overall rates of disease transmission mirror previous results on this farm. With such apparently effective decontamination (assuming that at least some sPMCA seeding ability is coincident with infectivity), how was infectivity able to persist within the environment and where does infectivity reside? Dust samples were collected in both the bioassay barn and also a barn subject to the same decontamination regime within the same farm (but remaining unoccupied). Within both of these barns dust had accumulated for three months that was able to seed sPMCA, indicating the accumulation of scrapie-containing material that was independent of the presence of sheep that may have been incubating and possibly shedding low amounts of infectivity.

This study clearly demonstrates the difficulty in removing scrapie infectivity from the farm environment. Practical and effective prion decontamination methods are still urgently required for decontamination of scrapie infectivity from farms that have had cases of scrapie and this is particularly relevant for scrapiepositive goatherds, which currently have limited genetic resistance to scrapie within commercial breeds.24 This is very likely to have parallels with control efforts for CWD in cervids.

Acknowledgements The authors thank the APHA farm staff, Tony Duarte, Olly Roberts and Margaret Newlands for preparation of the sheep pens and animal husbandry during the study. The authors also thank the APHA pathology team for RAMALT and postmortem examination.

Funding This study was funded by DEFRA within project SE1865.

Competing interests None declared.

https://veterinaryrecord.bmj.com/content/early/2019/01/02/vr.105054.long

Saturday, January 5, 2019

Rapid recontamination of a farm building occurs after attempted prion removal

https://prionprp.blogspot.com/2019/01/rapid-recontamination-of-farm-building.html

FRIDAY, DECEMBER 28, 2018

***> Chronic Wasting Disease CWD TSE Prion 2019 Where The Rubber Meets The Road

https://chronic-wasting-disease.blogspot.com/2018/12/chronic-wasting-disease-cwd-tse-prion.html


terry

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7397873 01/07/19 05:27 PM
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Is there a really short in redneck english version?

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398169 01/07/19 10:53 PM
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huh???

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398236 01/08/19 12:07 AM
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Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398259 01/08/19 12:31 AM
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Again? Really?

So.... then..... how do WE stop CWD?


Originally Posted By: Chunky Monkey
Never been to a camping world. I prefer Dick's to be honest.
Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398328 01/08/19 01:16 AM
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Cliff Notes version pleeeez.

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398334 01/08/19 01:22 AM
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TL;DR

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398349 01/08/19 01:33 AM
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***>This is very likely to have parallels with control efforts for CWD in cervids.

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398407 01/08/19 02:35 AM
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So, itís gonna be a bigger deal than Y2K?

Do I need to update my will?

Am I dead already?

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398549 01/08/19 04:18 AM
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popcorn


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_____________"Illegitimus non carborundum est"_______________

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Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398563 01/08/19 04:30 AM
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I'm filling my bathtub again, just like on 12/31/99, you know...just in case!

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398584 01/08/19 04:53 AM
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You have had two threads closed down in the last week. Why keep posting on the same thing? confused2

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: huntwest] #7398692 01/08/19 01:12 PM
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Originally Posted by huntwest
Is there a really short in redneck english version?


You canít remove prion from landscape once it is there, yet there are ranches/properties that have had a scrapie kil off(via THAC), that continue to use same facilities and pasture and have not had another outbreak.......even though itís apparently on fence posts and fly strips,

Also if itís in the ground itís in the vegetables..... so much for being a vegan.

Thank God we are all dieing anyway


Donate to TX Youth hunting program.... better to donate then to waste it in taxes

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Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: Jimbo1] #7398822 01/08/19 03:11 PM
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Originally Posted by Jimbo1
I'm filling my bathtub again, just like on 12/31/99, you know...just in case!

thats funny..i actually did that..lol

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7398863 01/08/19 03:56 PM
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Got ant studies out of the USA that support your theories?
Sybille Research facility had cattle in their pens for years, not months, and had no transmission of the prion to the cattle. Proven , not theorized.
Still waiting on all the human positives to surface. No cases in our neck of the woods where CWD was brought to be studied and is endemic now. Herds are doing fine too.

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7399358 01/08/19 11:48 PM
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I just detest the whole ďIím gonna copy pasta some inflammatory, misleading, & alarmist wall of text that furthers my personal agendaĒ of the poster.

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7399503 01/09/19 02:25 AM
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Who wrote that sh............t. I bet his wife has to sneak up on a pork chop to pet a dog!!!!


Thanks, Billy
Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: Jimbo1] #7399508 01/09/19 02:29 AM
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Originally Posted by Jimbo1
I'm filling my bathtub again, just like on 12/31/99, you know...just in case!


Hahahahahaha


Take Care,
Bub
Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7399764 01/09/19 01:59 PM
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Bigfoot is dying off because of CWD, and now there are very few left if any!

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7399812 01/09/19 02:37 PM
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I still hunt deer. I still eat deer. I'm still alive. That's all I need to know.


After Monday and Tuesday, even the calendar says W T F
Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7401291 01/11/19 01:04 AM
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I want to raise sheep one day after I semi-retire. Lamb is my favorite domestic meat to eat. \
A former sheep rancher near me that I used to buy lambs from each year is sort of discouraging me though.
I'm in Mississippi.

Re: Rapid recontamination of a farm building occurs after attempted prion removal [Re: flounder] #7402561 01/12/19 03:42 PM
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Thanks for posting this. It doesn't hurt to listen to science that challenges our opinions and views. Although CWD has hit home, I'm not panicking about it but I'm not ignoring it either.

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