@article{rice_baird_stikeleather_morrow_meyer_2014, title={Carbon dioxide system for on-farm euthanasia of pigs in small groups}, volume={22}, number={5}, journal={Journal of Swine Health and Production}, author={Rice, M. and Baird, C. and Stikeleather, L. and Morrow, W. E. M. and Meyer, R.}, year={2014}, pages={248–254} }
 @article{keelara_scott_morrow_hartley_griffin_gebreyes_thakur_2014, title={Comparative phenotypic and genotypic characterization of temporally related nontyphoidal salmonella isolated from human clinical cases, pigs, and the environment in North Carolina}, volume={11}, DOI={10.1089/fpd.2013.1630}, abstractNote={Nontyphoidal Salmonella infections caused by antimicrobial-resistant (AMR) strains are of great public health concern. We compared the phenotypic and genotypic relationships among temporally and spatially related AMR Salmonella isolates (n=1058) representing several predominant serovars, including Salmonella Typhimurium, Salmonella Typhimurium var. 5-, Salmonella Derby, Salmonella Heidelberg, Salmonella Muenchen, Salmonella Schwarzengrund, and Salmonella Rissen of human clinical cases (n=572), pig (n=212), and farm environment (n=274) origin in North Carolina. Antimicrobial susceptibility testing was performed using the broth microdilution method, and genotypic resistance determinants, including class I and II integrons, were identified. Overall, Salmonella isolates exhibited the highest frequency of resistance to tetracycline (50%), followed by sulfisoxazole (36%) and streptomycin (27%). We identified 16 different antimicrobial resistance genes, including extended spectrum and AmpC β-lactamases-producing genes (bla(TEM), bla(PSE), and bla(CMY-2)), in all the β-lactam- and cephalosporin-resistant Salmonella isolates from humans, pigs, and the environment. Class I integrons of 1-kb and 1.2-kb size were identified from all the three sources (humans, 66%; pigs, 85%; environment, 58%), while Class II integrons of 2-kb size were identified only in pig (10%) and environmental (19%) isolates. We detected genotypic similarity between Salmonella Typhimurium isolated from humans, pigs, and the environment while serovars Derby, Heidelberg, and Muenchen exhibited genotypic diversity. Detection of AMR Salmonella isolates from humans, pigs, and the environment is a concern for clinicians and veterinarians to mitigate the dissemination of AMR Salmonella strains.}, number={2}, journal={Foodborne Pathogens and Disease}, author={Keelara, S. and Scott, H. M. and Morrow, W. M. and Hartley, C. S. and Griffin, D. L. and Gebreyes, W. A. and Thakur, Siddhartha}, year={2014}, pages={156–164} }
 @article{meyer_morrow_stikeleather_baird_rice_byrne_halbert_styles_2014, title={Evaluation of carbon dioxide administration for on-site mass depopulation of swine in response to animal health emergencies}, volume={244}, ISSN={["1943-569X"]}, DOI={10.2460/javma.244.8.924}, abstractNote={apid methods for on-site swine depopulation are re-quired in the event of an animal health emergency in North America. The term animal health emergency, as used in this context, includes a wide range of poten-tial situations such as disease outbreaks, contamination with chemicals (eg, dioxin) or radionuclides (eg, cesi-um-137), and adverse animal welfare conditions creat-ed by transportation restrictions that severely limit feed deliveries and animal movement. As described by the AVMA, mass depopulation refers to methods by which large numbers of animals must be destroyed quickly and efficiently with as much consideration given to the welfare of the animals as practicable, but where the cir -cumstances and tasks facing those performing depopu-lation are understood to be extenuating.}, number={8}, journal={JAVMA-JOURNAL OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION}, author={Meyer, Robert E. and Morrow, W. E. Morgan and Stikeleather, Larry F. and Baird, Craig L. and Rice, J. Mark and Byrne, Haleh and Halbert, Burt V. and Styles, Darrel K.}, year={2014}, month={Apr}, pages={924–933} }
 @misc{meyer_morrow_stikeleather_styles_2014, title={Experience of breathing carbon dioxide Response}, volume={244}, number={11}, journal={Journal of the American Veterinary Medical Association}, author={Meyer, R. and Morrow, W. E. M. and Stikeleather, L. and Styles, D. K.}, year={2014}, pages={1244–1245} }
 @article{medardus_molla_nicol_morrow_rajala-schultz_kazwala_gebreyes_2014, title={In-Feed Use of Heavy Metal Micronutrients in US Swine Production Systems and Its Role in Persistence of Multidrug-Resistant Salmonellae}, volume={80}, ISSN={["1098-5336"]}, DOI={10.1128/aem.04283-13}, abstractNote={ABSTRACT}, number={7}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Medardus, Julius J. and Molla, Bayleyegn Z. and Nicol, Matthew and Morrow, W. Morgan and Rajala-Schultz, Paivi J. and Kazwala, Rudovick and Gebreyes, Wondwossen A.}, year={2014}, month={Apr}, pages={2317–2325} }
 @article{meyer_whitley_morrow_stikeleather_baird_rice_halbert_styles_whisnant_2013, title={Effect of physical and inhaled euthanasia methods on hormonal measures of stress in pigs}, volume={21}, number={5}, journal={Journal of Swine Health and Production}, author={Meyer, R. E. and Whitley, J. T. and Morrow, W. E. M. and Stikeleather, L. F. and Baird, C. L. and Rice, J. M. and Halbert, B. V. and Styles, D. K. and Whisnant, C. S.}, year={2013}, pages={261–269} }
 @article{robbins_artuso-ponte_moeser_morrow_spears_gebreyes_2013, title={Effects of quaternary benzo(c)phenanthridine alkaloids on growth performance, shedding of organisms, and gastrointestinal tract integrity in pigs inoculated with multidrug-resistant Salmonella spp}, volume={74}, DOI={10.2460/ajvr.74.12.1530}, abstractNote={Abstract}, number={12}, journal={American Journal of Veterinary Research}, author={Robbins, R. C. and Artuso-Ponte, V. C. and Moeser, A. J. and Morrow, W. E. M. and Spears, J. W. and Gebreyes, W. A.}, year={2013}, pages={1530–1535} }
 @article{funk_abley_bowman_gebreyes_morrow_tadesse_2013, title={Prevalence of Yersinia enterocolitica in Antimicrobial-Free and Conventional Antimicrobial Use Swine Production}, volume={10}, ISSN={["1535-3141"]}, DOI={10.1089/fpd.2012.1354}, abstractNote={Swine are the primary reservoir for foodborne illness associated with Yersinia enterocolitica. The use of antimicrobials in animal agriculture has been hypothesized as having a potential role in the increase in prevalence of zoonotic pathogens. The objective of this study was to compare the frequency of Y. enterocolitica fecal shedding in swine reared on farms with conventional antimicrobial use policies to farms that were antimicrobial free (ABF). Swine farms were selected from three regions in the United States. In each region, farms were categorized based on antimicrobial use policy. Fecal samples were collected from pigs on-farm within 48 h of harvest. The overall proportion of Y. enterocolitica and ail-harboring Y. enterocolitica-positive pigs was 10.9% and 4.0%, respectively. There were increased odds (odds ratio [OR] 6.8, 95% confidence interval [CI] 3.46-13.28) for a pig to be Y. enterocolitica positive if it was reared on an ABF farm as compared to a conventional farm. There was no significant association between farm antimicrobial use policy and isolation of an ail-harboring Y. enterocolitica from an individual pig (OR 1.8, 95% CI 0.90-3.61). The association of antimicrobial use policy with Y. enterocolitica shedding in feces should be interpreted cautiously, as antimicrobial use cannot be separated from other management factors (e.g., confinement or outdoor housing), which may be associated with risk of Y. enterocolitica in swine.}, number={6}, journal={FOODBORNE PATHOGENS AND DISEASE}, author={Funk, Julie A. and Abley, Melanie J. and Bowman, Andrew S. and Gebreyes, Wondwossen A. and Morrow, William E. Morgan and Tadesse, Daniel A.}, year={2013}, month={Jun}, pages={514–519} }
 @article{tadesse_bahnson_funk_morrow_abley_ponte_thakur_wittum_degraves_rajala-schultz_et al._2013, title={Yersinia enterocolitica of Porcine Origin: Carriage of Virulence Genes and Genotypic Diversity}, volume={10}, ISSN={["1556-7125"]}, DOI={10.1089/fpd.2011.1120}, abstractNote={Yersinia enterocolitica is an important foodborne pathogen, and pigs are recognized as a major reservoir and potential source of pathogenic strains to humans. A total of 172 Y. enterocolitica recovered from conventional and antimicrobial-free pig production systems from different geographic regions (North Carolina, Ohio, Michigan, Wisconsin, and Iowa) were investigated to determine their pathogenic significance to humans. Phenotypic and genotypic diversity of the isolates was assessed using antibiogram, serogrouping, and amplified fragment length polymorphism (AFLP). Carriage of chromosomal and plasmid-borne virulence genes were investigated using polymerase chain reaction. A total of 12 antimicrobial resistance patterns were identified. More than two-thirds (67.4%) of Y. enterocolitica were pan-susceptible, and 27.9% were resistant against β-lactams. The most predominant serogroup was O:3 (43%), followed by O:5 (25.6%) and O:9 (4.1%). Twenty-two of 172 (12.8%) isolates were found to carry Yersinia adhesion A (yadA), a virulence gene encoded on the Yersinia virulence plasmid. Sixty-nine (40.1%) isolates were found to carry ail gene. The ystA and ystB genes were detected in 77% and 26.2% of the strains, respectively. AFLP genotyping of isolates showed wide genotypic diversity and were grouped into nine clades with an overall genotypic similarity of 66.8-99.3%. AFLP analysis revealed that isolates from the same production system showed clonal relatedness, while more than one genotype of Y. enterocolitica circulates within a farm.}, number={1}, journal={FOODBORNE PATHOGENS AND DISEASE}, author={Tadesse, Daniel A. and Bahnson, Peter B. and Funk, Julie A. and Morrow, W. E. Morgan and Abley, Melanie J. and Ponte, Valeria A. and Thakur, Siddhartha and Wittum, Thomas and DeGraves, Fred J. and Rajala-Schultz, Paivi J. and et al.}, year={2013}, month={Jan}, pages={80–86} }
 @article{holt_heugten_graves_see_morrow_2011, title={Growth performance and antibiotic tolerance patterns of nursery and finishing pigs fed growth-promoting levels of antibiotics}, volume={136}, ISSN={["1878-0490"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79951956142&partnerID=MN8TOARS}, DOI={10.1016/j.livsci.2010.09.007}, abstractNote={The objective of this study was to evaluate the impact of growth-promoting levels of antibiotics in diets for nursery and finishing pigs on growth performance and antibiotic tolerance patterns. Gilts (n = 200, initial body weight was 6.2 ± 0.003 kg), were allotted based on body weight to one of four treatments in a 2 × 2 factorial randomized complete block design. Nursery treatments consisted of feeding no antibiotics (CON) or an antibiotic diet (ANTI) containing chlortetracycline (CTC; 55 mg/kg). At the end of the nursery phase, one-half of the pigs receiving CON were switched to a diet containing antibiotic (virginiamycin; VIR, 11 mg/kg) and one-half of the pigs receiving ANTI were switched to CON for the remainder of the trial. This created four treatments for the finishing phase, consisting of: control in nursery and finishing (CC), antibiotic in nursery, control in finishing (AC), control in nursery, antibiotic in finishing (CA), or antibiotics throughout (AT). The pigs were weighed at the diet changes during the nursery (weeks 1, 3, and 5) and finishing (weeks 7, 9, 13, 17, and 20) phases. Fecal samples were collected at all diet changes for isolation of fecal coliforms and Enterococcus and subsequently tested for tolerance to CTC and VIR. After 1 week, CON pigs weighed less (7.09 vs. 7.28 kg) and had lower ADG (149 vs. 180 g/day) and ADFI (174 vs. 192 g/day) than ANTI pigs (P < 0.05). No performance differences were observed during the remainder of the study. At the initiation of the study (week 0), the ability of coliforms to grow in the presence of CTC and VIR, respectively, were 68 and 73% and increased to 90 and 96% at week 19 (time effect, P < 0.001). At week 17, tolerance of coliforms to CTC was greater for CA (98%) than AC (86%, time × treatment effect, P < 0.004). Enterococcus tolerance to CTC at week 7 was lower for CC (55%) compared to AT (76%), AC (74%) and CA (83%, time × treatment effect, P < 0.001). At week 9, Enterococcus tolerant to CTC and VIR, respectively, was lower for CC (15 and 18%) than AT (31 and 40%), AC (35 and 35%), and CA (44 and 43%, time × treatment effect, P < 0.001). Antibiotic growth promoters had little impact on growth performance in clean, isolated facilities with high labor inputs. The tolerance of bacteria to antibiotics fluctuated over time and persisted regardless of the use of antibiotic growth promoters.}, number={2-3}, journal={LIVESTOCK SCIENCE}, author={Holt, J. P. and Heugten, E. and Graves, A. K. and See, M. T. and Morrow, W. E. M.}, year={2011}, month={Apr}, pages={184–191} }
 @article{tadesse_bahnson_funk_thakur_morrow_wittum_degraves_rajala-schultz_gebreyes_2011, title={Prevalence and Antimicrobial Resistance Profile of Campylobacter Spp. Isolated from Conventional and Antimicrobial-Free Swine Production Systems from Different U.S. Regions}, volume={8}, ISSN={["1556-7125"]}, DOI={10.1089/fpd.2010.0665}, abstractNote={We conducted a study to compare the prevalence and antimicrobial resistance profile of Campylobacter isolated from 34 farm-slaughter pair cohorts of pigs raised in conventional and antimicrobial-free (ABF) production systems. Isolates originated from four different states of two geographic regions (region 1--Ohio and Michigan; region 2--Wisconsin and Iowa). A total of 838 fecal and 1173 carcass samples were examined. Campylobacter isolates were speciated using multiplex polymerase chain reaction targeting ceuE and hipO genes. The minimum inhibitory concentration was determined using agar dilution to a panel of six antimicrobials: chloramphenicol, erythromycin, gentamicin, ciprofloxacin, nalidixic acid, and tetracycline. Campylobacter spp. was isolated from 472 of 838 pigs (56.3%). Campylobacter prevalence did not vary significantly based on production system (conventional [58.9%] and ABF [53.7%], odds ratio [OR] 1.4, 95% confidence interval [CI] 0.8-2.6, p = 0.24) or geographic region (region 1 [54.1%] and region 2 [58.2%], OR 1.02, 95% CI 0.6-1.9, p = 0.92). At slaughter plant, Campylobacter prevalence varied based on processing stages (19.4% at pre-evisceration, 25.3% at postevisceration, and 3.2% at postchill). Resistance was common to tetracycline (64.5%), erythromycin (47.9%), and nalidixic acid (23.5%). Campylobacter isolates from conventional production systems were more likely to be erythromycin resistant than from ABF (OR 3.2, 95% CI 1.4-7.2, p = 0.01). The proportion of ciprofloxacin-resistant Campylobacter coli isolates were 3.7% and 1.2% from ABF and conventional production systems, respectively. Thirty-seven out of 1257 C. coli (2.9%) were resistant to both erythromycin and ciprofloxacin, drugs of choice for treatment of invasive human campylobacteriosis. The finding of ciprofloxacin resistance, particularly from ABF herds, has significant implications on the potential role of risk factors other than mere antimicrobial use for production purposes.}, number={3}, journal={FOODBORNE PATHOGENS AND DISEASE}, author={Tadesse, Daniel A. and Bahnson, Peter B. and Funk, Julie A. and Thakur, Siddhartha and Morrow, William E. Morgan and Wittum, Thomas and DeGraves, Fred and Rajala-Schultz, Paivi and Gebreyes, Wondwossen A.}, year={2011}, month={Mar}, pages={367–374} }
 @article{molla_sterman_mathews_artuso-ponte_abley_farmer_rajala-schultz_morrow_gebreyes_2010, title={Salmonella enterica in Commercial Swine Feed and Subsequent Isolation of Phenotypically and Genotypically Related Strains from Fecal Samples}, volume={76}, ISSN={["0099-2240"]}, DOI={10.1128/aem.01169-10}, abstractNote={ABSTRACT}, number={21}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Molla, Bayleyegn and Sterman, Allyson and Mathews, Jennifer and Artuso-Ponte, Valeria and Abley, Melanie and Farmer, William and Rajala-Schultz, Paivi and Morrow, W. E. Morgan and Gebreyes, Wondwossen A.}, year={2010}, month={Nov}, pages={7188–7193} }
 @article{zewde_robbins_abley_house_morrow_gebreyes_2009, title={Comparison of Swiffer Wipes and Conventional Drag Swab Methods for the Recovery of Salmonella in Swine Production Systems}, volume={72}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028X-72.1.142}, abstractNote={The main goal of this study was to assess the efficacy of Swiffer wipes in comparison to conventional drag swabs for the recovery of Salmonella. A total of 800 samples (400 Swiffer wipes and 400 drag swabs) were aseptically collected from randomly selected swine barns before disinfection with specific biocides and within 2 h after disinfection. From each barn, 10 samples of each swab type and negative controls were collected. Salmonellae were isolated from 43 (10.8%) of 400 drag swabs and 34 (8.5%) of 400 Swiffer wipes. There was a significant reduction in Salmonella postdisinfection as identified with both sampling procedures irrespective of the type of biocide used (P < 0.05). With the drag swabs, salmonellae were detected in 15% of the samples before disinfection versus 6.5% after disinfection, whereas with the Swiffer wipes, 13 and 4% of the samples were positive pre- and postdisinfection, respectively. Of the total 720 fecal samples collected from pigs placed in the disinfected barns, 132 (18.3%) were Salmonella positive. About 65 and 98% of the Salmonella isolates from swine barns and fecal samples, respectively, were resistant to one or more of the antimicrobials tested. Multidrug resistance was found in 35.7% of the isolates from barn swabs and 56.4% of the isolates from fecal samples. Results of this study suggest that the conventional drag swab method results in better recovery of Salmonella than does the Swiffer wipe method and thus could be a useful sampling method in monitoring Salmonella. Pentaresistant Salmonella (mainly R-type ACSSuT) was more common in fecal samples than in environmental samples.}, number={1}, journal={JOURNAL OF FOOD PROTECTION}, author={Zewde, Bayleyegn Molla and Robbins, Rebecca and Abley, Melanie J. and House, Brandon and Morrow, W. E. Morgan and Gebreyes, Wondwossen A.}, year={2009}, month={Jan}, pages={142–146} }
 @article{wright_carver_siletzky_romine_morrow_kathariou_2008, title={Longitudinal study of prevalence of Campylobacter jejuni and Campylobacter coli from turkeys and swine grown in close proximity}, volume={71}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028X-71.9.1791}, abstractNote={Eastern North Carolina is a major contributor to both turkey and swine production in the United States. In this region, turkeys and swine are frequently grown in close proximity and by common growers. To further characterize colonization of turkeys and swine with Campylobacter in such a setting, we investigated the prevalence of thermophilic campylobacters in eight paired operations involving turkey farms in close proximity to finishing swine farms. All 15 surveyed flocks and 15 herds were Campylobacter positive at one or more sampling times. Campylobacter was isolated from 1,310 (87%) of the 1,512 turkey samples and 1,116 (77%) of the 1,448 swine samples. Most (> 99%) campylobacters from swine samples were Campylobacter coli, found in 59 to 97% of the samples from the different herds. Both Campylobacterjejuni and C. coli were recovered from the turkey flocks (overall prevalences of 52 and 35%, respectively). Prevalence among flocks ranged from 31 to 86% for C. jejuni and 0 to 67% for C. coli, and both species were recovered from most flocks. Relative prevalence of C. coli was higher in young birds (brooders), whereas C. jejuni predominated in grow-out birds (P < 0.0001). The prevalence of C. coli in a swine herd was generally not a good predictor for prevalence of this species in the corresponding turkey flock. These findings indicate that even though turkeys and swine grown in proximity to each other were commonly colonized with thermophilic campylobacters, the relative prevalences of C. jejuni and C. coli appear to be host associated.}, number={9}, journal={JOURNAL OF FOOD PROTECTION}, author={Wright, S. L. and Carver, D. K. and Siletzky, R. M. and Romine, S. and Morrow, W. E. M. and Kathariou, S.}, year={2008}, month={Sep}, pages={1791–1796} }
 @article{thakur_morrow_funk_bahnson_gebreyes_2008, title={Molecular epidemiologic investigation of Campylobacter coli in swine production systems, using multilocus sequence typing (vol 72, pg 5666, 2006)}, volume={74}, ISSN={["0099-2240"]}, DOI={10.1128/aem.02326-07}, abstractNote={Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough St., Raleigh, North Carolina 27606; Department of Animal Science, North Carolina State University, Raleigh, North Carolina 27606; Department of Veterinary Preventive Medicine, The Ohio State University, Columbus, Ohio; and Department of Medical Sciences, University of Wisconsin, Madison, Wisconsin}, number={1}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Thakur, Siddhartha and Morrow, W. E. Morgan and Funk, Julie A. and Bahnson, Peter B. and Gebreyes, Wondwossen A.}, year={2008}, month={Jan}, pages={342–342} }
 @article{gebreyes_thakur_morrow_2006, title={Comparison of prevalence, antimicrobial resistance, and occurrence of multidrug-resistant Salmonella in antimicrobial-free and conventional pig production}, volume={69}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028x-69.4.743}, abstractNote={Conventional swine production evolved to routinely use antimicrobials, and common occurrence of antimicrobial-resistant Salmonella has been reported. There is a paucity of information on the antimicrobial resistance of Salmonella in swine production in the absence of antimicrobial selective pressure. Therefore, we compared the prevalence and antimicrobial resistance of Salmonella isolated from antimicrobial-free and conventional production systems. A total of 889 pigs and 743 carcasses were sampled in the study. Salmonella prevalence was significantly higher among the antimicrobial-free systems (15.2%) than the conventional systems (4.2%) (odds ratio [OR] = 4.23; P < 0.05). Antimicrobial resistance was detected against 10 of the 12 antimicrobials tested. The highest frequency of resistance was found against tetracycline (80%), followed by streptomycin (43.4%) and sulfamethoxazole (36%). Frequency of resistance to most classes of antimicrobials (except tetracycline) was significantly higher among conventional farms than antimicrobial-free farms, with ORs ranging from 2.84 for chloramphenicol to 23.22 for kanamycin at the on-farm level. A total of 28 antimicrobial resistance patterns were detected. A resistance pattern with streptomycin, sulfamethoxazole, and tetracycline (n = 130) was the most common multidrug resistance pattern. There was no significant difference in the proportion of isolates with this pattern between the conventional (19.5%) and the antimicrobial-free systems (18%) (OR = 1.8; P > 0.05). A pentaresistance pattern with ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline was strongly associated with antimicrobial-free groups (OR = 5.4; P = 0.01). While showing the higher likelihood of finding antimicrobial resistance among conventional herds, this study also implies that specific multidrug-resistant strains may occur on antimicrobial-free farms. A longitudinal study with a representative sample size is needed to reach more conclusive results of the associations detected in this study.}, number={4}, journal={JOURNAL OF FOOD PROTECTION}, author={Gebreyes, WA and Thakur, S and Morrow, WEM}, year={2006}, month={Apr}, pages={743–748} }
 @article{morrow_meyer_roberts_lascelles_2006, title={Financial and welfare implications of immediately euthanizing compromised nursery pigs}, volume={14}, number={1}, journal={Journal of Swine Health and Production}, author={Morrow, W. E. M. and Meyer, R. E. and Roberts, J. and Lascelles, D.}, year={2006}, pages={25–34} }
 @article{thakur_morrow_funk_bahnson_gebreyes_2006, title={Molecular epidemiologic investigation of Campylobacter coli in swine production systems, using multilocus sequence typing}, volume={72}, ISSN={["1098-5336"]}, DOI={10.1128/AEM.00658-06}, abstractNote={ABSTRACT}, number={8}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Thakur, Siddhartha and Morrow, W. E. Morgan and Funk, Julie A. and Bahnson, Peter B. and Gebreyes, Wondwossen A.}, year={2006}, month={Aug}, pages={5666–5669} }
 @article{gebreyes_thakur_morrow_2005, title={Campylobacter coli: prevalence and antimicrobial resistance in antimicrobial-free (ABF) swine production systems}, volume={56}, ISSN={["1460-2091"]}, DOI={10.1093/jac/dki305}, abstractNote={OBJECTIVES
To determine the prevalence and antimicrobial resistance of Campylobacter species in swine reared in the intensive and extensive antimicrobial-free (ABF) production systems at farm and slaughter. In the ABF system, antimicrobials are neither used for growth promotion nor therapeutic purposes.


METHODS
Swine faecal and carcass swabs were collected from 10 groups of pigs (five each from intensive and extensive ABF farms) at the finishing farm and the slaughter plant. A total of 292 pigs at farm (extensive 118; intensive 174) and 254 carcass swabs (extensive 134; intensive 120) were collected during the study. Campylobacter species were isolated under microaerobic conditions and confirmed by biochemical testing. Up to three presumptive Campylobacter colonies per positive pig/carcass were further characterized. Speciation was done by PCR, targeting ceuE and hipO genes for Campylobacter coli and Campylobacter jejuni, respectively. The isolates were tested for their antimicrobial resistance profile using the agar dilution method against six antimicrobials.


RESULTS
A total of 526 Campylobacter isolates were cultured from 292 pigs and 254 carcasses sampled. All the isolates were found to be C. coli. Overall prevalence of C. coli was 55.8% on farm (55% extensive and 56.3% intensive) and 26% at slaughter (32.8% extensive and 18.3% intensive). There was no significant difference in C. coli between the intensive and extensive systems on the finishing farms (P = 0.83). At post-chill stage, C. coli were isolated only from the extensively reared ABF pigs. Antimicrobial resistance against ciprofloxacin (MIC > 4 mg/L) was found at the farm level in both the intensive- and extensive-reared groups. The erythromycin/nalidixic acid/tetracycline resistance pattern (3%) was the most common pattern in multidrug-resistant C. coli.


CONCLUSIONS
This study highlights the high prevalence of diverse and antimicrobial-resistant C. coli in the ABF production systems of swine. This is the first study reporting the isolation of ciprofloxacin-resistant strains from ABF pigs in the USA and warrants concern.}, number={4}, journal={JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY}, author={Gebreyes, WA and Thakur, S and Morrow, WEM}, year={2005}, month={Oct}, pages={765–768} }
 @article{meyer_morrow_2005, title={Carbon dioxide for emergency on-farm euthanasia of swine}, volume={13}, number={4}, journal={Journal of Swine Health and Production}, author={Meyer, R. E. and Morrow, W. E. M.}, year={2005}, pages={210–217} }
 @article{gebreyes_davies_turkson_morgan morrow_funk_altier_thakur_2004, title={Characterization of Antimicrobial-Resistant Phenotypes and Genotypes among Salmonella enterica Recovered from Pigs on Farms, from Transport Trucks, and from Pigs after Slaughter}, volume={67}, ISSN={0362-028X}, url={http://jfoodprotection.org/doi/abs/10.4315/0362-028X-67.4.698}, DOI={10.4315/0362-028X-67.4.698}, abstractNote={The main objectives of this study were to determine antimicrobial resistance patterns among Salmonella serotypes and to evaluate the role of transport trucks in dissemination of antimicrobial-resistant strains of Salmonella. Salmonella from groups of nursery and finishing pigs on farms, from trucks, and from pigs after slaughter were compared using serotyping, patterns of antimicrobial resistance, and pulsed-field gel electrophoresis patterns. The five farms included in the study yielded 858 isolates representing 27 Salmonella serovars. The most common resistance observed (80% of all isolates) was to tetracycline; resistance to ampicillin (42%), chloramphenicol (31%), amoxicillin/clavulanic acid (30%), and piperacillin (31%) also were common. We found a correlation between serovar and antimicrobial resistance. High correlation was found between Salmonella Typhimurium var. Copenhagen and chloramphenicol resistance (Spearman rank correlation, rho = 0.7). Multidrug resistance was observed primarily in Salmonella Typhimurium var. Copenhagen (94%) and Salmonella Typhimurium (93%) and was much less common in the other common serovars, including Salmonella Derby (7%) and Salmonella Heidelberg (8%). Of the 225 isolates exhibiting the most common pentaresistance pattern in this study, amoxicillin/clavulanic acid-ampicillin-chloramphenicol-piperacillin-tetracycline, 220 (98%) were Salmonella Typhimurium var. Copenhagen, and 86% of the isolates of this serovar had this pattern. Isolates from the trucks were similar, based on pulsed-field gel electrophoresis patterns, to those from the cecum and mesenteric lymph nodes of pigs on two of the farms, suggesting the probable infection of pigs during transport. Class I integrons were also common among various serovars.}, number={4}, journal={Journal of Food Protection}, author={Gebreyes, Wondwossen A. and Davies, Peter R. and Turkson, Paa-Kobina and Morgan Morrow, W. E. and Funk, Julie A. and Altier, Craig and Thakur, Siddhartha}, year={2004}, month={Apr}, pages={698–705} }
 @article{gebreyes_davies_turkson_morrow_funk_altier_2004, title={Salmonella enterica serovars from pigs on farms and after slaughter and validity of using bacteriologic data to define herd Salmonella status}, volume={67}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028X-67.4.691}, abstractNote={The primary objective of this study was to evaluate the validity of using data obtained from slaughtered pigs for farm-level epidemiologic studies of Salmonella. The study involved groups of pigs from five farms. Salmonella isolates were obtained from on-farm samples, and a total of 370 on-farm and an additional 486 isolates from samples collected after commercial slaughter were subsequently tested. Preharvest samples included feces of individual animals from defined groups of nursery and finishing pigs on commercial farms and swabs from trucks. Postslaughter samples were cecal contents and mesenteric lymph node samples. The concordance between Salmonella serovars isolated from on-farm samples and those serovars isolated after slaughter varied widely among farms. Results of paired lymph node and cecal cultures were strongly associated (odds ratio, 7.0), but the agreement between on-farm and postslaughter results at the pig level was poor (kappa = 0.34). The results support recent findings that risk of exposure to Salmonella during transport and lairage remains a concern under contemporary industry conditions. The findings further imply that slaughter plant studies based on phenotyping of Salmonella alone (such as serovars) may not reliably indicate the Salmonella status of commercial swine farms.}, number={4}, journal={JOURNAL OF FOOD PROTECTION}, author={Gebreyes, WA and Davies, PR and Turkson, PK and Morrow, WEM and Funk, JA and Altier, C}, year={2004}, month={Apr}, pages={691–697} }
 @article{moeser_see_heugten_morrow_kempen_2003, title={Diet and evaluators affect perception of swine waste odor: An educational demonstration}, volume={81}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-2142759654&partnerID=MN8TOARS}, DOI={10.2527/2003.81123211x}, abstractNote={An educational program was developed for extension agents, faculty, and graduate students to illustrate the effect of diet composition on odor from swine manure. Participants in this program first received a 2-h detailed review on odorous compounds in manure and the effect of diet on odor. For the second portion of the training, nine manure samples were used from pigs fed diets formulated with feed ingredients predicted to have different effects on odor emission or a nutritionally adequate corn-soybean meal diet. Participants were instructed to rate the odor from these samples for pleasantness, irritation, and intensity on a scale of 0 (best) to 8 (worst), using manure from the corn-soybean meal fed pig as the reference with a score defined as 4 for each variable. Results obtained were summarized and discussed before concluding the program. Participants were Cooperative Extension Agents (n = 13) with swine responsibilities and graduate students and faculty (n = 8). The manure from the diet with the worst odor scores (1% garlic) was rated at 70% more odorous across the three odor variables (P < 0.05) than the diet with the least odorous manure (purified diet). Even though a reference sample was used, individual participants differed in their perception of irritation across samples (P < 0.05), ranging in average score across diets from 2.4 (moderately better than reference) to 5.0 (slightly worse than reference). With extension agents, a 1 to 7 scale (very interesting to not at all interesting) was used for evaluation of the training session. Participants found the material to be interesting (mean = 1.7, SD = 0.7) and the training exercise to be well organized and coherent in its presentation (mean = 1.8, SD = 0.7). Participants enjoyed this training and learned that differences in odor are achievable through altering diet composition, and that the response to swine odor depends on individual odor perception.}, number={12}, journal={Journal of Animal Science}, author={Moeser, A. J. and See, M. T. and Heugten, Eric and Morrow, W. E. M. and Kempen, T. Van}, year={2003}, pages={3211–3215} }
 @article{withers_correa_morrow_stebbins_seriwatana_webster_boak_vaughn_2002, title={Antibody levels to hepatitis E virus in North Carolina swine workers, non-swine workers, swine, and murids}, volume={66}, ISSN={["0002-9637"]}, DOI={10.4269/ajtmh.2002.66.384}, abstractNote={In a cross-sectional serosurvey, eastern North Carolina swine workers (n = 165) were compared with non-swine workers (127) for the presence of antibodies to hepatitis E virus as measured by a quantitative immunoglobulin enzyme-linked immunosorbent assay. Using a cutoff of 20 Walter Reed U/ml, swine-exposed subjects had a 4.5-fold higher antibody prevalence (10.9%) than unexposed subjects (2.4%). No evidence of past clinical hepatitis E or unexplained jaundice could be elicited. Swine (84) and mice (61), from farm sites in the same region as exposed subjects, were also tested. Antibody prevalence in swine (overall = 34.5%) varied widely (10.0-91.7%) according to site, but no antibody was detected in mice. Our data contribute to the accumulating evidence that hepatitis E may be a zoonosis and specifically to the concept of it as an occupational infection of livestock workers.}, number={4}, journal={AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE}, author={Withers, MR and Correa, MT and Morrow, M and Stebbins, ME and Seriwatana, J and Webster, WD and Boak, MB and Vaughn, DW}, year={2002}, month={Apr}, pages={384–388} }
 @article{eisemann_morrow_see_davies_zering_2002, title={Effect of feed withdrawal prior to slaughter on prevalence of gastric ulcers in pigs}, volume={220}, ISSN={["0003-1488"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0037085335&partnerID=MN8TOARS}, DOI={10.2460/javma.2002.220.503}, abstractNote={Abstract}, number={4}, journal={JOURNAL OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION}, author={Eisemann, JH and Morrow, WEM and See, MT and Davies, PR and Zering, K}, year={2002}, month={Feb}, pages={503–506} }
 @article{morrow_see_eisemann_davies_zering_2002, title={Effect of withdrawing feed from swine on meat quality and prevalence of Salmonella colonization at slaughter}, volume={220}, ISSN={["0003-1488"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0037085491&partnerID=MN8TOARS}, DOI={10.2460/javma.2002.220.497}, abstractNote={Abstract}, number={4}, journal={JOURNAL OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION}, author={Morrow, WEM and See, MT and Eisemann, JH and Davies, PR and Zering, K}, year={2002}, month={Feb}, pages={497–502} }
 @article{kihlstrom_morrow_davies_luginbuhl_2001, title={Assessing the progressive decontamination of farrowing crate floors by measuring the decrease in aerobic bacteria}, volume={9}, number={2}, journal={Journal of Swine Health and Production}, author={Kihlstrom, S. L. and Morrow, M. and Davies, P. R. and Luginbuhl, G. H.}, year={2001}, pages={65–69} }
 @article{morrow_ferket_middleton_2000, title={Alternative methods of carcass disposal}, volume={46}, ISBN={1352-9749}, journal={Pig Journal}, author={Morrow, W. E. M. and Ferket, P. R. and Middleton, T.}, year={2000}, pages={104} }
 @article{gebreyes_davies_morrow_funk_altier_2000, title={Antimicrobial resistance of Salmonella isolates from swine}, volume={38}, number={12}, journal={Journal of Clinical Microbiology}, author={Gebreyes, W. A. and Davies, P. R. and Morrow, W. E. M. and Funk, J. A. and Altier, C.}, year={2000}, pages={4633–4636} }
 @article{davies_funk_morrow_2000, title={Fecal shedding of Salmonella by gilts before and after introduction to a swine breeding farm}, volume={8}, number={1}, journal={Swine Health and Production}, author={Davies, P. R. and Funk, J. A. and Morrow, W. E. M.}, year={2000}, pages={25–29} }
 @article{funk_davies_morrow_nichols_2000, title={Temporal patterns of Salmonella enterica prevalence and serotypes in breeding and growing swine populations}, journal={Proceedings of the 9th symposium of the International Society for Veterinary Epidemiology and Economics, Breckenridge, Colorado, USA, August 6-11 2000}, publisher={International Society for Veterinary Epidemiology and Economics (ISVEE)}, author={Funk, J. A. and Davies, P. R. and Morrow, W. E. M. and Nichols, M. A.}, year={2000}, pages={203} }
 @article{morrow_1999, title={Euthanasia hazards}, volume={14}, number={2}, journal={Occupational Medicine. State of the Art Reviews in Occupational Medicine}, author={Morrow, W. E. M.}, year={1999}, pages={235–246} }
 @article{davies_funk_morrow_1999, title={Fecal shedding of Salmonella by a cohort of finishing pigs in North Carolina}, volume={7}, number={5}, journal={Swine Health and Production}, author={Davies, P. and Funk, J. and Morrow, W. E. M.}, year={1999}, pages={231–234} }
 @article{morrow_1999, title={Swine-L, AASP Message Board, and members@aasp.org: Three systems to help you communicate}, volume={7}, number={1}, journal={Swine Health and Production}, author={Morrow, M.}, year={1999}, pages={44–45} }
 @article{davies_bovee_funk_morrow_jones_deen_1998, title={Isolation of Salmonella serotypes from feces of pigs raised in a multiple-site production system}, volume={212}, number={12}, journal={Journal of the American Veterinary Medical Association}, author={Davies, P. R. and Bovee, F. G. E. M. and Funk, J. A. and Morrow, W. E. M. and Jones, F. T. and Deen, J.}, year={1998}, pages={1925–1929} }
 @article{hill_langley_morrow_1998, title={Occupational injuries and illnesses reported by zoo veterinarians in the United States}, volume={29}, number={4}, journal={Journal of Zoo and Wildlife Medicine}, author={Hill, D. J. and Langley, R. L. and Morrow, W. M.}, year={1998}, pages={371–385} }
 @article{davies_morrow_deen_gamble_patton_1998, title={Seroprevalence of Toxoplasma gondii and Trichinella spiralis in finishing swine raised in different production systems in North Carolina, USA}, volume={36}, ISSN={["1873-1716"]}, DOI={10.1016/S0167-5877(98)00072-5}, abstractNote={We compared the seroprevalence of both Toxoplasma gondii and Trichinella spiralis in finishing pigs raised in different production systems in North Carolina, USA. Farms were either finishing sites using all-in/all-out management of buildings in multiple-site systems (14 farms) or farrow-to-finish systems using continuous-flow management of finishing barns or outdoor accommodation 14 farms). The two groups of herds differed with respect to several management variables. A total of 13 of 2238 samples (0.58%) were positive for antibodies to Toxoplasma gondii using the modified agglutination test. Of these, 12 were from 63 pigs sampled on a farm where finishing pigs were kept on pasture. Only one of 1752 (0.057%) samples from pigs kept in total confinement systems was seropositive. Only one pig of 2183 (0.046%) tested positive by ELISA for antibodies against T. spiralis. In this region, management practices in modern production systems appear to be adequate to virtually eliminate the risk of infection of finishing pigs with both T. gondii and T. spiralis.}, number={1}, journal={PREVENTIVE VETERINARY MEDICINE}, author={Davies, PR and Morrow, WEM and Deen, J and Gamble, HR and Patton, S}, year={1998}, month={Jul}, pages={67–76} }
 @article{langley_morrow_1997, title={Deaths resulting from animal attacks in the United States}, volume={8}, ISSN={["1545-1534"]}, DOI={10.1580/1080-6032(1997)008[0008:DRFAAI]2.3.CO;2}, abstractNote={The objective of this study was to elucidate the etiology and frequency of deaths in the United States from encounters with animals. The number of deaths from venomous and nonvenomous animals is reported annually to the US Department of Health and Human Services and published in Vital Statistics of the United States. This study is a survey of all animal-related fatalities listed as E-codes 905–906 reported in the Vital Statistics of the United States from 1979 through 1990. Data were extracted uniformly from the annual reports and analyzed using descriptive statistics. From 1979 through 1990, there were 1882 animal-related deaths in the United States. Venomous animals caused 718 deaths; nonvenomous animals caused 1164 deaths. Most deaths occurred among white males. The home site was the location of injury for the majority of deaths. The majority of venomous animal-related deaths were from hymenoptera; “other specified animal” caused the majority of nonvenomous deaths. An annual average of 157 deaths from animal attacks occurred in the United States between 1979 and 1990. Both fatal and nonfatal animal-related injuries are under-recognized public health hazards. Health care providers should educate their patients on exercising caution around animals, seeking medical care after an animal injury, carrying epinephrine kits if they have a history of systemic reactions to insect stings, and wearing helmets and other protective equipment when riding or working around large animals.}, number={1}, journal={WILDERNESS & ENVIRONMENTAL MEDICINE}, author={Langley, RL and Morrow, WE}, year={1997}, month={Feb}, pages={8–16} }
 @article{davies_morrow_rountree_miller_1997, title={Epidemiologic evaluation of decubital ulcers in farrowing sows}, volume={210}, number={8}, journal={Journal of the American Veterinary Medical Association}, author={Davies, P. R. and Morrow, W. E. and Rountree, W. G. and Miller, D. C.}, year={1997}, pages={1173–1178} }
 @article{davies_morrow_jones_deen_fedorka cray_harris_1997, title={Prevalence of salmonella in finishing swine raised in different 

production systems in North Carolina, USA}, volume={119}, ISSN={0950-2688 1469-4409}, url={http://dx.doi.org/10.1017/s095026889700784x}, DOI={10.1017/S095026889700784X}, abstractNote={We compared the prevalence of salmonella in faecal samples from
 

finishing pigs and in feed 

samples from swine herds in North Carolina, USA. Farms were either 

finishing sites using all-in/all-out management of buildings in 

multiple-site systems (14 farms) or farrow-to-finish 

systems using continuous flow management of finishing barns (15 

farms). The two groups of 

herds differed with respect to several management variables. Salmonella
 were 

isolated from 565 

of 2288 (24·6%) faecal samples and from at least 1 faecal sample
 

on 24 of 29 (83%) farms. 

Predominant serotypes were S. derby, S. typhimurium 

(including copenhagen), S. heidelberg, S. 

worthington and S. mbandaka. Fewer farrow-to-finish farms
 

were detected as positive compared 

with all-in/all-out farms. Prevalence was lower for pigs raised on
 

slotted floors compared with 

all other floor types, and was highest for pigs raised on dirt 

lots. Modern methods of raising 

pigs in multiple-site production systems, using all-in/all-out 

management of finishing pigs, 

appear to have no benefit in reducing the prevalence of salmonella 

compared with conventional farrow-to-finish systems.}, number={2}, journal={Epidemiology and Infection}, publisher={Cambridge University Press (CUP)}, author={Davies, P. R. and Morrow, W. E. M. and Jones, F. T. and Deen, J. and Fedorka Cray, P. J. and Harris, I. T.}, year={1997}, month={Oct}, pages={237–244} }
 @article{davies_morrow_jones_deen_fedorkacray_gray_1997, title={Risk of shedding salmonella organisms by market age hogs in a barn with open flush gutters}, volume={210}, number={3}, journal={Journal of the American Veterinary Medical Association}, author={Davies, P. R. and Morrow, W. E. and Jones, F. T. and Deen, J. and Fedorkacray, P. J. and Gray, J. T.}, year={1997}, pages={386–389} }
 @article{nespeca_vaillancourt_morrow_1997, title={Validation of a poultry biosecurity survey}, volume={31}, ISSN={["0167-5877"]}, DOI={10.1016/S0167-5877(96)01122-1}, abstractNote={A questionnaire for farm managers was designed, to obtain information regarding biosecurity on Ontario commercial broiler chicken and turkey operations, and then pre-tested. The questions that could be validated were verifiable by seeing the facility, by using farm records or by interviewing technical personnel other than the survey respondent. The survey was validated using a convenience sample of 24 farms from two companies. For 15 questions with dichotomous responses, the sensitivity ranged from 16.7 to 100%; the specificity ranged from 0 to 100%. For example, fences and gates seen during the farm visit were not accurately reported on the survey (poor sensitivity). Chance-corrected agreement was low (κ < 0.4) for 34 questions, fair to good (0.4 < κ < 0.8) for 25 questions, and excellent (κ ⪢ 0.8) for seven questions. The percent agreement for questions where only one of the possible options was observed on validation ranged from 60.9 to 100%. Five questions with continuous numeric variables were analysed. A difference was observed (P < 0.1) between the survey and validation data for three questions regarding the number of birds, the bird sources and the downtime between flocks. In spite of pre-testing, the lack of clear wording and the absence of definitions for technical terms appeared to reduce validity. Response bias seems to be an issue with biosecurity surveys. The value of validating questionnaires before their use in epidemiologic research is confirmed.}, number={1-2}, journal={PREVENTIVE VETERINARY MEDICINE}, author={Nespeca, R and Vaillancourt, JP and Morrow, WEM}, year={1997}, month={Jul}, pages={73–86} }
 @article{morrow_o'quinn_barker_erickson_post_mccaw_1995, title={Composting as a suitable technique for managing swine mortalities}, volume={3}, number={6}, journal={Swine Health and Production}, author={Morrow, W. E. M. and O'Quinn, P. and Barker, J. and Erickson, G. and Post, K. and McCaw, M.}, year={1995}, pages={236} }
 @article{morrow_hansen_o'quinn_nelson_1995, title={Effect of the water acidifier BIO SAVORTM on postweaning pig performance}, volume={3}, number={4}, journal={Swine Health and Production}, author={Morrow, W. E. M. and Hansen, J. A. and O'Quinn, P. and Nelson, C.}, year={1995}, pages={151} }
 @article{morrow_iglesias_stanislaw_stephenson_erickson_1994, title={Effect of a mycoplasma vaccine on average daily weight gain in swine}, volume={2}, number={6}, journal={Swine Health and Production}, author={Morrow, W. E. M. and Iglesias, G. and Stanislaw, C. and Stephenson, A. and Erickson, G.}, year={1994}, pages={13} }
 @article{morrow_ferket_1993, title={The disposal of dead pigs: A review}, volume={1}, number={3}, journal={Swine Health and Production}, author={Morrow, W. M. and Ferket, P. R.}, year={1993}, pages={7} }