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Schumacher LL, Huss AR, Cochrane RA, Stark CR, Woodworth JC, Bai J, Poulsen EG, Chen Q, Main RG, Zhang J, Gauger PC, Ramirez A, Derscheid RJ, Magstadt DM, Dritz SS, Jones CK. Characterizing the rapid spread of porcine epidemic diarrhea virus (PEDV) through an animal food manufacturing facility. PLoS One 2017; 12:e0187309. [PMID: 29095859 PMCID: PMC5667810 DOI: 10.1371/journal.pone.0187309] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 10/17/2017] [Indexed: 02/07/2023] Open
Abstract
New regulatory and consumer demands highlight the importance of animal feed as a part of our national food safety system. Porcine epidemic diarrhea virus (PEDV) is the first viral pathogen confirmed to be widely transmissible in animal food. Because the potential for viral contamination in animal food is not well characterized, the objectives of this study were to 1) observe the magnitude of virus contamination in an animal food manufacturing facility, and 2) investigate a proposed method, feed sequencing, to decrease virus decontamination on animal food-contact surfaces. A U.S. virulent PEDV isolate was used to inoculate 50 kg swine feed, which was mixed, conveyed, and discharged into bags using pilot-scale feed manufacturing equipment. Surfaces were swabbed and analyzed for the presence of PEDV RNA by quantitative real-time polymerase chain reaction (qPCR). Environmental swabs indicated complete contamination of animal food-contact surfaces (0/40 vs. 48/48, positive baseline samples/total baseline samples, positive subsequent samples/total subsequent samples, respectively; P < 0.05) and near complete contamination of non-animal food-contact surfaces (0/24 vs. 16/18, positive baseline samples/total baseline samples, positive subsequent samples/total subsequent samples, respectively; P < 0.05). Flushing animal food-contact surfaces with low-risk feed is commonly used to reduce cross-contamination in animal feed manufacturing. Thus, four subsequent 50 kg batches of virus-free swine feed were manufactured using the same system to test its impact on decontaminating animal food-contact surfaces. Even after 4 subsequent sequences, animal food-contact surfaces retained viral RNA (28/33 positive samples/total samples), with conveying system being more contaminated than the mixer. A bioassay to test infectivity of dust from animal food-contact surfaces failed to produce infectivity. This study demonstrates the potential widespread viral contamination of surfaces in an animal food manufacturing facility and the difficulty of removing contamination using conventional feed sequencing, which underscores the importance for preventing viruses from entering and contaminating such facilities.
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Affiliation(s)
- Loni L. Schumacher
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, United States of America
| | - Anne R. Huss
- Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas, United States of America
| | - Roger A. Cochrane
- Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas, United States of America
| | - Charles R. Stark
- Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas, United States of America
| | - Jason C. Woodworth
- Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas, United States of America
| | - Jianfa Bai
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, United States of America
| | - Elizabeth G. Poulsen
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, United States of America
| | - Qi Chen
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Rodger G. Main
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Jianqiang Zhang
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Phillip C. Gauger
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Alejandro Ramirez
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Rachel J. Derscheid
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Drew M. Magstadt
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Steve S. Dritz
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, United States of America
| | - Cassandra K. Jones
- Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas, United States of America
- * E-mail:
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Torkzaban S, Bradford SA, van Genuchten MT, Walker SL. Colloid transport in unsaturated porous media: the role of water content and ionic strength on particle straining. JOURNAL OF CONTAMINANT HYDROLOGY 2008; 96:113-127. [PMID: 18068262 DOI: 10.1016/j.jconhyd.2007.10.006] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 10/19/2007] [Accepted: 10/24/2007] [Indexed: 05/25/2023]
Abstract
Packed column and mathematical modeling studies were conducted to explore the influence of water saturation, pore-water ionic strength, and grain size on the transport of latex microspheres (1.1 microm) in porous media. Experiments were carried out under chemically unfavorable conditions for colloid attachment to both solid-water interfaces (SWI) and air-water interfaces (AWI) using negatively charged and hydrophilic colloids and modifying the solution chemistry with a bicarbonate buffer to pH 10. Interaction energy calculations and complementary batch experiments were conducted and demonstrated that partitioning of colloids to the SWI and AWI was insignificant across the range of the ionic strengths considered. The breakthrough curve and final deposition profile were measured in each experiment indicating colloid retention was highly dependent on the suspension ionic strength, water content, and sand grain size. In contrast to conventional filtration theory, most colloids were found deposited close to the column inlet, and hyper-exponential deposition profiles were observed. A mathematical model, accounting for time- and depth-dependent straining, produced a reasonably good fit for both the breakthrough curves and final deposition profiles. Experimental and modeling results suggest that straining--the retention of colloids in low velocity regions of porous media such as grain junctions--was the primary mechanism of colloid retention under both saturated and unsaturated conditions. The extent of stagnant regions of flow within the pore structure is enhanced with decreasing water content, leading to a greater amount of retention. Ionic strength also contributes to straining, because the number of colloids that are held in the secondary energy minimum increases with ionic strength. These weakly associated colloids are prone to be translated to stagnation regions formed at grain-grain junctions, the solid-water-air triple point, and dead-end pores and then becoming trapped.
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Affiliation(s)
- Saeed Torkzaban
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA
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Dowdle W, van der Avoort H, de Gourville E, Delpeyroux F, Desphande J, Hovi T, Martin J, Pallansch M, Kew O, Wolff C. Containment of polioviruses after eradication and OPV cessation: characterizing risks to improve management. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2006; 26:1449-69. [PMID: 17184392 DOI: 10.1111/j.1539-6924.2006.00844.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The goal of the World Health Organization is to stop routine use of oral poliovirus vaccine shortly after interruption of wild poliovirus transmission. A key component of this goal is to minimize the risk of reintroduction by destruction of polioviruses except in an absolute minimum number of facilities that serve essential functions and implement effective containment. Effective containment begins with a complete facility risk assessment. This article focuses on characterizing the risks of exposure to polioviruses from the essential vaccine production, quality control, and international reference and research facilities that remain. We consider the potential exposure pathways that might lead to a poliovirus reintroduction, including para-occupational exposures and releases to the environment, and review the literature to provide available estimates and a qualitative assessment of containment risks. Minimizing the risk of poliovirus transmission from a poliovirus facility to increasingly susceptible communities is a crucial and ongoing effort requiring understanding and actively managing the potential exposure pathways.
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Affiliation(s)
- Walter Dowdle
- Polio Eradication Program, The Task Force for Child Survival and Development, 750 Commerce Dr., Suite 400, Decatur, GA 30030, USA.
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Straub TM, Pepper IL, Gerba CP. Comparison of PCR and cell culture for detection of enteroviruses in sludge-amended field soils and determination of their transport. Appl Environ Microbiol 1995; 61:2066-8. [PMID: 7646051 PMCID: PMC167478 DOI: 10.1128/aem.61.5.2066-2068.1995] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
PCR and cell culture assays for enteroviruses were conducted on soil samples collected from an experimental farm that had received mesophilic anaerobically digested sludge for the past 7 years. Of 24 samples assayed, 21 samples were positive by PCR, implying that at least some viral nucleic acid sequences remained intact. However, these viral particles were unable to infect the Buffalo Green Monkey cell line used in subsequent cell culture assays. It is significant that positive PCR detection of nucleic acid sequences occurred even though the most recent sludge application was 3 months prior to soil sampling. Viral nucleic acid sequences were detected by PCR at points vertically and laterally displaced from sludge injections, illustrating significant transport of viruses. Rainfall and irrigation events may have contributed to viral transport.
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Affiliation(s)
- T M Straub
- Department of Soil and Water Science, University of Arizona, Tucson 85721, USA
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Straub TM, Pepper IL, Gerba CP. Hazards from pathogenic microorganisms in land-disposed sewage sludge. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 1993; 132:55-91. [PMID: 8346362 DOI: 10.1007/978-1-4684-7065-9_3] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Sewage sludge is a complex mixture of organic and inorganic compounds of biological and mineral origin that are precipitated from wastewater and sewage during primary, secondary, and tertiary sewage treatment. Present in these sludges are significant numbers of microorganisms that include viral, bacterial, protozoan, fungal, and helminth pathogens. The treatment of sludge to reduce biochemical oxygen demand, solids content, and odor is not always effective in reducing numbers of pathogens. This becomes a public health concern because the infectious dose for some of these pathogens may be as low as 1 particle (virus) to 50 organisms (Giardia). When sludge is applied to land for agricultural use and landfill compost, these pathogens can survive from days (bacteria) to months (viruses) to years (helminth eggs), depending on environmental conditions. Shallow aquifers can become contaminated with pathogens from sludge and, depending on groundwater flow, these organisms may travel significant distances from the disposal site. Communities that rely on groundwater for domestic use can become exposed to these pathogens, leading to a potential disease outbreak. Currently, methods to determine the risk of disease from pathogens in land-disposed sludge are inadequate because the sensitivity of pathogen detection is poor. The application of recombinant DNA technology (gene probes and polymerase chain reaction) to environmental samples may provide increased sensitivity for detecting specific pathogens in land-disposed sludge and greatly improved risk assessment models for our exposure to these sources of pathogens.
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Affiliation(s)
- T M Straub
- Department of Soil and Water Science, University of Arizona, Tucson 85721
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Hurst CJ, Schaub SA, Sobsey MD, Farrah SR, Gerba CP, Rose JB, Goyal SM, Larkin EP, Sullivan R, Tierney JT. Multilaboratory evaluation of methods for detecting enteric viruses in soils. Appl Environ Microbiol 1991; 57:395-401. [PMID: 1849712 PMCID: PMC182723 DOI: 10.1128/aem.57.2.395-401.1991] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Two candidate methods for the recovery and detection of viruses in soil were subjected to round robin comparative testing by members of the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group. Selection of the methods, designated "Berg" and "Goyal," was based on results of an initial screening which indicated that both met basic criteria considered essential by the task group. Both methods utilized beef extract solutions to achieve desorption and recovery of viruses from representative soils: a fine sand soil, an organic muck soil, a sandy loam soil, and a clay loam soil. One of the two methods, Goyal, also used a secondary concentration of resulting soil eluants via low-pH organic flocculation to achieve a smaller final assay volume. Evaluation of the two methods was simultaneously performed in replicate by nine different laboratories. Each of the produced samples was divided into portions, and these were respectively subjected to quantitative viral plaque assay by both the individual, termed independent, laboratory which had done the soil processing and a single common reference laboratory, using a single cell line and passage level. The Berg method seemed to produce slightly higher virus recovery values; however, the differences in virus assay titers for samples produced by the two methods were not statistically significant (P less than or equal to 0.05) for any one of the four soils. Despite this lack of a method effect, there was a statistically significant laboratory effect exhibited by assay titers from the independent versus reference laboratories for two of the soils, sandy loam and clay loam.
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Affiliation(s)
- C J Hurst
- United States Environmental Protection Agency, Cincinnati, Ohio 45268
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Wang DS, Gerba CP, Lance JC. Effect of soil permeability on virus removal through soil columns. Appl Environ Microbiol 1981; 42:83-8. [PMID: 6266338 PMCID: PMC243967 DOI: 10.1128/aem.42.1.83-88.1981] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Laboratory experiments were performed on four different soils, using 100 cm long columns, to determine the extent of virus movement when wastewater percolated through the soils at various hydraulic flow rates. Unchlorinated secondary sewage effluent seeded with either poliovirus type 1 (strain LSc) or echovirus type 1 (isolate V239) was continuously applied to soil columns for 3 to 4 days at constant flow rates. Water samples were extracted daily from ceramic samplers at various depths of the column for the virus assay. The effectiveness of virus removal from wastewater varied greatly among the different soil types but appeared to be largely related to hydraulic flow rates. At a flow rate of 33 cm/day, Anthony sandy loam removed 99% of seeded poliovirus within the first 7 cm of the column. At flow rates of 300 cm/day and above, Rubicon sand gave the poorest removal of viruses; less than 90% of the seeded viruses were removed by passage of effluent through the entire length of the soil column. By linear regression analyses, the rate of virus removal in soil columns was found to be negatively correlated with the flow of the percolating sewage effluent. There was no significant difference in rate of removal between poliovirus and echovirus in soil columns 87 cm long. The rate of virus removal in the upper 17 cm of the soil column was found to be significantly greater than in the lower depths of the soil column. This study suggests that the flow rate of water through the soil may be the most important factor in predicting the potential of virus movement into the groundwater. Furthermore, the length of the soil column is critical in obtaining useful data to predict virus movement into groundwater.
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