Evaluating the Effect of Manufacturing Porcine Epidemic Diarrhea Virus (PEDV)-Contaminated Feed on Subsequent Feed Mill Environmental Surface Contamination
L. L. SchumacherR. A. CochraneCaitlin E. EvansJ. R. KalivodaJason C WoodworthC. R. StarkCassandra K JonesRodger MainJianqiang ZhangSteven S DritzPhillip C. Gauger
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This study aimed to utilize the only known pilot feed mill facility approved for pathogenic feed agent use in the United States to evaluate the effect of manufacturing Porcine Epidemic Diarrhea Virus (PEDV)-contaminated feed on subsequent feed mill environmental surface contamination. In this study, PEDV inoculated feed was manufactured and conveyed on equipment along with four subsequent batches of PEDV-free feed. Equipment and environmental surfaces were sampled using swabs and analyzed for the presence of PEDV RNA by PCR. The experiment was replicated three times with decontamination of the feed mill and all equipment between replications. Overall, environmental swabs indicated widespread surface contamination of the equipment and work area after a PEDV contaminated batch of feed was processed. There was little difference in environmental sample cycle threshold (Ct) values after manufacturing each of the subsequent PEDV-negative feed batches. In summary, introduction of PEDV-infected feed into a feed mill will likely result in widespread contamination of equipment and surfaces, even after several batches of PEDV-free feed are produced. Eliminating the PEDV RNA from the feed mill environment was challenging and required procedures that are not practical to apply on a regular basis in a feed mill. This data suggests that it is extremely important to prevent the introduction of PEDV-contaminated feed, ingredients, or other vectors of transmission to minimize PEDV-risk. More research should be conducted to determine if contaminated surfaces can lead to PEDV infectivity and to determine the best feed mill PEDV-decontamination strategies.Keywords:
Human decontamination
Animal Feed
Living 4-6 week-aged San Yuan white pigs (Suzhou,China) were used in skin decontamination experiments. Following a standard procedure, SM series of decontamination agents were used for decontamination of liquid nuclides. The results of immediate decontamination were as follows: K (decontamination efficiency) =97. 7% (decontamination factor DF = 43. 5) for 131I;K99% (DF100) for 90Sr/90Y,MFP and U+TRU; K =99. 9% (DF = 1000) for 137Cs.In 3 h-delayed decontamination,DF = 27-67 ( K = 96. 3%-98.5%) for the nuclides mentioned above. When the initiatory MFP contamination increased from 20 to 300 s-1 ?cm-2,the value of DF by immediate decontamination increased from 20 to 173 with the remaining activity not higher than 10 Bq ?cm-2,and no additional decontamination was needed. For radioactive ash contamination of skin,DF = 57-1000 ( K=98. 2% - 99. 9%) in 4 h-delayed decontamination. SM series of decontamination agents are neutral liquid or cream without any irritative effect on skin. They are effective and easy to use in skin decontamination.
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The preliminary experiment was performed to obtain the operating conditions of soil washing decontamination process such as decontamination agent, decontamination temperature, decontamination time and ratio of soil and decontamination agent. To estimate decontamination efficiency, particle size of soil was classified into three categories; ≥ 2.0 mm, 2.0 ~ 0.21 mm and ≤ 0.21 mm. Major target of this experiment was decontamination of Cs-137. The difference of decontamination efficiency using water and neutral salts as decontamination agent is not high. It is concluded that the best temperature of decontamination agent is normal temperature and the best decontamination time was about 60 minutes. And the best ratio of soil and decontamination agent is 1:10. In case of Cs decontamination for fine soils, the decontamination results using neutral salts such as Na2CO3 and Na3PO4 shows some limits while using strong acid such as sulfuric acid or hydrochloric acid shows high decontamination efficiency(≥ 90%). But we conclude that decontamination using strong acid is also inappropriate because of the insufficiency of decontamination efficiency for highly radioactive fine soils and the difficulty for treatment of secondary liquid waste. It is estimated that the best decontamination process is to use water as decontamination agent for particles which can be decontaminated to clearance level, after particle size separation.
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Living 4-6 week-aged San Yuan white pigs (Suzhou, China) were used in skin decontamination experiments. Following a standard procedure, SM series of decontamination agents were used for decontamination of liquid nuclides. The results of immediate decontamination were as follows: K(decontamination efficiency) = 97. 7% (decontamination factor DF = 43. 5) for 131I; K 99% (DF100) for 90Sr/90Y, MFP and U+TRU; K =99. 9% (DF = 1000) for 137Cs. In 3 h-delayed decontamination,DF = 27-67 ( K =96. 3%-98. 5%) for the nuclides mentioned above. When the initiatory MFP contamination increased from 20 to 300 s-1 . cm-2, the value of DF by immediate decontamination increased from 20 to 173 with the remaining activity not higher than 10 Bq . cm-2, and no additional decontamination was needed. For radioactive ash contamination of skin, DF=57-1000 ( K =:98. 2%-99. 9%) in 4 h-delayed decontamination. SM series of decontamination agents are neutral liquid or cream without any irritative effect on skin. They are effective and easy to use in skin decontamination.
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More recently emerging strains of porcine epidemic diarrhea virus (PEDV) cause severe diarrhea and especially high mortality rates in infected piglets, leading to substantial economic loss to worldwide swine industry. These outbreaks urgently call for updated and effective PEDV vaccines. Better understanding in PEDV biology and improvement in technological platforms for virus production can immensely assist and accelerate PEDV vaccine development. In this study, we explored the ability of PEDV nucleocapsid (N) protein in improving viral yields in cell culture systems. We demonstrated that PEDV N expression positively affected both recovery of PEDV from infectious clones and PEDV propagation in cell culture. Compared to Vero E6 cells, Vero E6 cells expressing PEDV N could accelerate growth of a slow-growing PEDV strain to higher peak titers by 12 hours or enhance the yield of a vaccine candidate strain by two orders of magnitude. Interestingly, PEDV N also slightly enhances replication of porcine reproductive and respiratory virus, a PEDV relative in the Nidovirales order. These results solidify the importance of N in PEDV recovery and propagation and suggest a potentially useful consideration in designing vaccine production platforms for PEDV or closely related pathogens.
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This article analyzes the data on chemical decontamination methods dealing with radioactively contaminated surfaces. It considers the composition of solutions most commonly used for decontamination purposes. Numerical data are presented to illustrate the effectiveness of various decontamination methods. The paper considers an experiment on the decontamination of stainless steel samples with water following a cavitation treatment. The study reveals a dependence between the decontamination efficiency and the treatment time of the contaminated surface with a decontamination solution based on cavitation-activated water, which appears to be comparable with the results of the one involving an alkaline solution.
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This report documents the results of a test of the New Calcining Facility (NWCF) process decontamination system. The decontamination system test occurred in December 1981, during non-radioactive testing of the NWCF. The purpose of the decontamination system test was to identify equipment whose design prevented effective calcine removal and decontamination. Effective equipment decontamination was essential to reduce radiation fields for in-cell work after radioactive processing began. The decontamination system test began with a pre-decontamination inspection of the equipment. The pre- decontamination inspection documented the initial condition and cleanliness of the equipment. It provided a basis for judging the effectiveness of the decontamination. The decontamination consisted of a series of equipment flushes using nitric acid and water. A post-decontamination equipment inspection determined the effectiveness of the decontamination. The pre-decontamination and post-decontamination equipment inspections were documented with photographs. The decontamination system was effective in removing calcine from most of the NWCF equipment as evidenced by little visible calcine residue in the equipment after decontamination. The decontamination test identified four areas where the decontamination system required improvement. These included the Calciner off-gas line, Cyclone off-gas line, fluidizing air line, and the Calciner baffle plates. Physical modifications to enhance decontamination were made to those areas, resulting in an effective NWCF decontamination system.
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This report documents the results of a test of the New Calcining Facility (NWCF) process decontamination system. The decontamination system test occurred in December 1981, during non-radioactive testing of the NWCF. The purpose of the decontamination system test was to identify equipment whose design prevented effective calcine removal and decontamination. Effective equipment decontamination was essential to reduce radiation fields for in-cell work after radioactive processing began. The decontamination system test began with a pre-decontamination inspection of the equipment. The pre-decontamination inspection documented the initial condition and cleanliness of the equipment. It provided a basis for judging the effectiveness of the decontamination. The decontamination consisted of a series of equipment flushes using nitric acid and water. A post-decontamination equipment inspection determined the effectiveness of the decontamination. The pre-decontamination and post-decontamination equipment inspections were documented with hotographs. The decontamination system was effective in removing calcine from most of the NWCF equipment as evidenced by little visible calcine residue in the equipment after decontamination. The decontamination test identified four areas where the decontamination system required improvement. These included the Calciner off-gas line, Cyclone off-gas line, fluidizing air line, and the Calciner baffle plates. Physical modifications to enhance decontamination were made to those areas, resulting in an effective NWCF decontamination system.
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The contamination of platinum with nuclear fission products and its decontamination has been studied. Platinum plates were contaminated by soaking in a solution of fission products. The contamination increased with increase of the soaking time, and was saturated in about 3 hr. It was confirmed by the methods of autoradiography, electron microscopy and optical microscopy that the contamination was markedly affected by the surface condition of platinum. The results of the experiments of the decontamination are summarized as follows: (1) Decontamination with tap water: A sample soaked in the solution of fission products only for a short time was easy to decontaminate and the amount of the residual contamination reached equilibrium more rapidly than in the long-soaked sample. (2) Decontamination with acids: HCl, HNO3, H2SO4, H3PO4 and HF were tried. The effect of temperature on the decontamination was very significant. The decontamination with HCl of high temperature was more effective than with the other acids. (3) Decontamination with fused salts: The decontamination with fused KHSO4 was more effective than with the acids and other fused salts. Only one immersion of the contaminated platinum plate into fused KHSO4 could remove 99.4% of the contamination. Finally, it may be confirmed that the degree of the contamination of platinum with fission products is very low and it is easy to decontaminate it with the decontaminating agents such as HCl and KHSO4.
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The paper presents research of the process of decontamination of chemical protection suits. The results of the research show the effectiveness of selected decontamination techniques. In experiments took into account the influence of the contaminant, the time of decontamination, the type of the decontamination agent and the use of mechanical support in removing the contaminant. The research has shown how to minimize the negative action of hazardous substances on protective clothing and show the problem of the possibility of secondary contamination. They demonstrate the impact of each factors on the quality of decontamination and showed that small changes in the process of decontamination significantly affect the safety of the rescuer. The key to effective decontamination is the synergy effect of the studied parameters. This approach will allow efficient and effective execution of the decontamination process, minimize the risk of contact between rescuers and the contaminant and prevent secondary contamination.
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In January 2014, approximately 9 months following the initial detection of porcine epidemic diarrhea (PED) in the USA, the first case of PED was confirmed in a swine herd in south-western Ontario. A follow-up epidemiological investigation carried out on the initial and 10 subsequent Ontario PED cases pointed to feed as a common risk factor. As a result, several lots of feed and spray-dried porcine plasma (SDPP) used as a feed supplement were tested for the presence of PEDV genome by real-time RT-PCR assay. Several of these tested positive, supporting the notion that contaminated feed may have been responsible for the introduction of PEDV into Canada. These findings led us to conduct a bioassay experiment in which three PEDV-positive SDPP samples (from a single lot) and two PEDV-positive feed samples supplemented with this SDPP were used to orally inoculate 3-week-old piglets. Although the feed-inoculated piglets did not show any significant excretion of PEDV, the SDPP-inoculated piglets shed PEDV at a relatively high level for ≥9 days. Despite the fact that the tested PEDV genome positive feed did not result in obvious piglet infection in our bioassay experiment, contaminated feed cannot be ruled out as a likely source of this introduction in the field where many other variables may play a contributing role.
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