Pre-harvest risk factors for Salmonella enterica in pork production

Food Research International

Volumn 45, Issue 2, 2012, Pages 634-640

  Rostagno, Marcos H ^a   Callaway, Todd R ^a  

^a AGRICULTURAL RESEARCH SERVICE   (United States)

Author keywords

Epidemiology; Risk factors; Salmonella; Swine

Indexed keywords

BIO-SECURITY; CONTROL PROGRAM; PORK INDUSTRY; PORK PRODUCTION; POTENTIAL SOURCES; PRODUCTION STAGE; RISK FACTORS; SALMONELLA ENTERICA; SALMONELLA INFECTIONS; SCIENTIFIC KNOWLEDGE; SWINE;

DISEASES; EPIDEMIOLOGY; FARMS; HARVESTING; MAMMALS; MEATS;

SALMONELLA;

BACTERIA (MICROORGANISMS); SALMONELLA; SALMONELLA ENTERICA; SUIDAE;

EID: 84857417901     PISSN: 09639969     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.foodres.2011.04.041     Document Type: Review

References (103)

1. Abrahantes J.C., Bollaerts K., Aerts M., Ogunsanya V., Van der Stede Y. Salmonella serosurveillance: Different statistical methods to categorise pig herds based on serological data. Preventive Veterinary Medicine 2009, 89(1-2):59-66.
2. Alban, L., Baptista, F. M., Mogelmose, V., Sorensen, L. L., Christensen, H., Aabo, S., et al. (in press). Salmonella surveillance and control for finisher pigs and pork in Denmark-A case study. Food Research International, doi:10.1016/j.foodres.2011.02.050.
3. Averos X., Knowles T.G., Brown S.N., Warriss P.D., Gosalvez L.F. Factors affecting the mortality of pigs being transported to slaughter. The Veterinary Record 2008, 163(13):386-390.
4. Bahnson P.B., Fedorka-Cray P.J., Ladely S.R., Mateus-Pinilla N.E. Herd-level risk factors for Salmonella enterica subsp. enterica in U.S. market pigs. Preventive Veterinary Medicine 2006, 76:249-262.
5. Baptista F.M., Dahl J., Nielsen L.R. Factors influencing Salmonella carcass prevalence in Danish pig abattoirs. Preventive Veterinary Medicine 2010, 95:231-238.
6. Beloeil P.A., Chauvin C., Proux K., Fablet C., Madec F., Alioum A. Risk factors for Salmonella seroconversion of fattening pigs in farrow-to-finish herds. Veterinary Research 2007, 38:835-848.
7. Beloeil P.A., Chauvin C., Proux K., Madec F., Fravalo P., Alioum A. Impact of the Salmonella status of market-age pigs and the pre-slaughter process on Salmonella caecal contamination at slaughter. Veterinary Research 2004, 35:513-530.
8. Beloeil P.A., Fravalo P., Fablet C., Jolly J.P., Eveno E., Hascoet Y., et al. Risk factors for Salmonella enterica subsp. enterica shedding by market-age pigs in French farrow-to-finish herds. Preventive Veterinary Medicine 2004, 63:103-120.
9. Berends B.R., Van Knapen F., Mossel D.A.A., Burt S.A., Snijders J.M.A. Impact on human health of Salmonella spp. on pork in The Netherlands and the anticipated effects of some currently proposed control strategies. International Journal of Food Microbiology 1998, 44:219-229.
10. Berends B.R., Van Knapen F., Snijders J.M.A., Mossel D.A.A. Identification and quantification of risk factors regarding Salmonella spp. on pork carcasses. International Journal of Food Microbiology 1997, 36:199-206.
11. Botteldoorn N., Herman L., Rijpens N., Heyndrickx M. Phenotypic and molecular typing of Salmonella strains reveals different contamination sources in two commercial pig slaughterhouses. Applied and Environmental Microbiology 2004, 70(9):5305-5314.
12. Boughton C., Egan J., Kelly G., Markey B., Leonard N. Quantitative examination of Salmonella spp. in the lairage environment of a pig abattoir. Foodborne Pathogens and Disease 2007, 4(1):26-32.
13. Boughton C., Egan J., Kelly G., Markey B., Leonard N. Rapid infection of pigs following exposure to environments contaminated with different levels of Salmonella typhimurium. Foodborne Pathogens and Disease 2007, 4(1):33-40.
14. Boyen F., Haesebrouck F., Maes D., Van Immerseel F., Ducatelle R., Pasmans F. Non-typhoidal Salmonella infections in pigs: A closer look at epidemiology, pathogenesis and control. Veterinary Microbiology 2008, 130:1-19.
15. Carstensen B., Christensen J. Herd size and sero-prevalence of Salmonella enterica in Danish swine herds: A random-effects model for register data. Preventive Veterinary Medicine 1998, 34:191-203.
16. Crump J.A., Griggin P.M., Angulo F.J. Bacterial contamination of animal feed and its relationship to human foodborne illness. Clinical Infectious Diseases 2002, 35:859-865.
17. Dahl J. Cross-sectional epidemiological analysis of the relations between different herd factors and Salmonella seropositivity. Epidemiologie et Sante Animale 1997, 31-32:4.23.1-4.23.3.
18. Davies R.H., Dalziel R., Gibbens J.C., Wilesmith J.W., Ryan J.M.B., Evans S.J., et al. National survey for Salmonella in pigs, cattle and sheep at slaughter in Great Britain (1999-2000). Journal of Applied Microbiology 2004, 96(4):750-760.
19. Davies P.R., Hurd H.S., Funk J.A., Fedorka-Cray P.J., Jones F.T. The role of contaminated feed in the epidemiology and control of Salmonella enterica in pork production. Foodborne Pathogens and Disease 2004, 1(4):202-215.
20. Davies P.R., Morrow W.E.M., Jones F.T., Deen J., Fedorka-Cray P.J., Harris I.T. Prevalence of Salmonella in finishing swine raised in different production systems in North Carolina, USA. Epidemiology and Infection 1997, 119:237-244.
21. De Busser E.V., Maes D., Houf K., Dewulf J., Imberechts H., Bertrand S., et al. Detection and characterization of Salmonella in lairage, on pig carcasses and intestines in five slaughterhouses. International Journal of Food Microbiology 2011, 145(1):279-286.
22. de Jong A., Bywater R., Butty P., Deroover E., Godinho K., Klein U., et al. A pan-European survey of antimicrobial susceptibility towards human-use antimicrobial drugs among zoonotic and commensal enteric bacteria isolated from healthy food-producing animals. The Journal of Antimicrobial Chemotherapy 2009, 63(4):733-744.
23. Delhalle L., De Sadeleer L., Bollaerts K., Farnir F., Saegerman C., Korsak N., et al. Risk factors for Salmonella and hygiene indicators in the 10 largest Belgian pig slaughterhouses. Journal of Food Protection 2008, 71(7):1320-1329.
24. Dorr P.M., Tadesse D.A., Zewde B.M., Fry P., Thakur S., Gebreyes W.A. Longitudinal study of Salmonella dispersion and the role of environmental contamination in commercial swine production systems. Applied and Environmental Microbiology 2009, 75(6):1478-1486.
25. Eblen D., Barlow K.E., Naugle A.L. U.S. Food Safety and Inspection Service testing for Salmonella in selected raw meat and poultry products in the United States, 1998 through 2003: An establishment-level analysis. Journal of Food Protection 2006, 69(11):2600-2606.
26. Farzan A., Friendship R.M., Dewey C.E., Poppe C., Funk J. Evaluation of the risk factors for shedding Salmonella with or without antimicrobial resistance in swine using multinomial regression method. Zoonosis and Public Health 2010, 57(Suppl. 1):85-93.
27. Farzan A., Friendship R.M., Dewey C.E., Poppe C., Funk J., Muckle C.A. A longitudinal study of the Salmonella status on Ontario swine farms within the time period 2001-2006. Foodborne Pathogens and Disease 2008, 5(5):579-588.
28. Farzan A., Friendship R.M., Dewey C.E., Warriner K., Poppe C., Klotins K. Prevalence of Salmonella spp. on Canadian pig farms using liquid or dry feeding. Preventive Veterinary Medicine 2006, 73:241-254.
29. Fedorka-Cray P.J., Kelley L.C., Stabel T.J., Gray J.T., Laufer J.A. Alternate routes of invasion may affect pathogenesis of Salmonella typhimurium in swine. Infection and Immunity 1995, 63:2658-2664.
30. Fedorka-Cray P.J., Whipp S.C., Isaacson R.E., Nord N., Lager K. Transmission of Salmonella typhimurium to swine. Veterinary Microbiology 1994, 41(4):333-344.
31. Funk J.A., Davies P.R., Nichols M.A. The effect of fecal sample weight on detection of Salmonella enterica in swine feces. Journal of Veterinary Diagnostic Investigation 2000, 12(5):412-418.
32. Funk J.A., Davies P.R., Nichols M.A. Longitudinal study of Salmonella enterica in growing pigs reared in multiple-site swine production systems. Veterinary Microbiology 2001, 83:45-60.
33. Funk J.A., Harris I.T., Davies P.R. Comparison of fecal culture and Danish Mix-ELISA for determination of Salmonella enterica subsp. enterica prevalence in growing swine. Veterinary Microbiology 2005, 107:115-126.
34. Funk J.A., LeJeune J.T., Wittum T.E., Rajala-Schultz P.J. The effect of subtherapeutic chlortetracycline on antimicrobial resistance in the fecal flora of swine. Microbial Drug Resistance 2006, 12(3):210-218.
35. Funk J.A., Wittum T.E., LeJeune J.T., Rajala-Schultz P.J., Bowman A., Mack A. Evaluation of stocking density and subtherapeutic chlortetracycline on Salmonella enterica subsp. enterica shedding in growing swine. Veterinary Microbiology 2007, 124:202-208.
36. Garcia-Feliz C., Carvajal A., Collazos J.A., Rubio P. Herd-level risk factors for faecal shedding of Salmonella enterica in Spanish fattening pigs. Preventive Veterinary Medicine 2009, 91:130-136.
37. Garcia-Feliz C., Collazos J.A., Carvajal A., Vidal A.B., Aladuena A., Ramiro R., et al. Salmonella enterica infections in Spanish swine fattening units. Zoonoses and Public Health 2007, 54(8):294-300.
38. Gebreyes W.A., Bahnson P.B., Funk J.A., McKean J., Patchanee P. Seroprevalence of Trichinella, Toxoplasma, and Salmonella in antimicrobial-free and conventional swine production systems. Foodborne Pathogens and Disease 2008, 5(2):199-203.
39. Gebreyes W.A., Davies P.R., Turkson P.K., Morrow W.E., Funk J.A., Altier C. Salmonella enterica serovars from pigs on farms and after slaughter and validity of using bacteriologic data to define herd Salmonella status. Journal of Food Protection 2004, 67(4):691-697.
40. Gebreyes W.A., Thakur S., Morrow W.E.M. Comparison of prevalence, antimicrobial resistance, and occurrence of multidrug-resistant Salmonella in antimicrobial-free and conventional pig production. Journal of Food Protection 2006, 69(4):743-748.
41. Gray J.T., Fedorka-Cray P.J., Stabel T.J., Kramer T.T. Natural transmission of Salmonella choleraesuis in swine. Applied and Environmental Microbiology 1996, 62(1):141-146.
42. Griffith R.W., Schwartz K.J., Meyerholz D.K. Salmonella. Diseases of swine 2006, 739-754. Blackwell Publishing, Ames. 9th ed. B.E. Straw, J.J. Zimmerman, S. D'Allaire, D.J. Taylor (Eds.).
43. Guo C., Hoekstra R.M., Schroeder C.M., Pires S.M., Ong K.L., Hartnett E., et al. Application of Bayesian techniques to model the burden of human salmonellosis attributable to U.S. food commodities at the point of processing: Adaptation of a Danish model. Foodborne Pathogens and Disease 2011, 8(4):509-516.
44. Hald T., Vose D., Wegener H.C., Koupeev T. A Bayesian approach to quantify the contribution of animal-food sources to human salmonellosis. Risk Analysis 2004, 24(1):255-269.
45. Hautekiet V., Geert V., Marc V., Rony G. Development of a sanitary risk index for Salmonella seroprevalence in Belgian pig farms. Preventive Veterinary Medicine 2008, 86:75-92.
46. Hedemann M.S., Mikkelsen L.L., Naughton P.J., Jensen B.B. Effect of feed particle size and feed processing on morphological characteristics in the small and large intestine of pigs and on adhesion of Salmonella enterica serovar Typhimurium DT12 in the ileum in vitro. Journal of Animal Science 2005, 83(7):1554-1562.
47. Hotes S., Kemper N., Traulsen I., Rave G., Krieter J. Risk factors for Salmonella infection in fattening pigs-An evaluation of blood and meat juice samples. Zoonoses and Public Health 2010, 57(Suppl. 1):30-38.
48. Hurd H.S., Gailey J.K., McKean J.D., Rostagno M.H. Rapid infection in market-weight swine following exposure to a Salmonella typhimurium contaminated environment. American Journal of Veterinary Research 2001, 62(8):1194-1197.
49. Hurd H.S., McKean J.D., Griffith R.D., Rostagno M.H. Estimation of the Salmonella enterica prevalence in finishing swine. Epidemiology and Infection 2004, 132(1):127-135.
50. Hurd H.S., McKean J.D., Griffith R.W., Wesley I.V., Rostagno M.H. Salmonella enterica infections in market swine with and without transport and holding. Applied and Environmental Microbiology 2002, 68(5):2376-2381.
51. Kranker S., Alban L., Boes J., Dahl J. Longitudinal study of Salmonella enterica serotype Typhimurium infection in three Danish farrow-to-finish swine herds. Journal of Clinical Microbiology 2003, 41(6):2282-2288.
52. Kranker S., Dahl J., Wingstrand A. Bacteriological and serological examination and risk factor analysis of Salmonella occurrence in sow herds, including risk factors for high Salmonella seroprevalence in receiver finishing herds. Berliner und Münchener Tierärztliche Wochenschrift 2001, 114(9-10):350-352.
53. Leontides L.S., Grafanakis E., Genigeorgis C. Factors associated with the serological prevalence of Salmonella enterica in Greek finishing swine herds. Epidemiology and Infection 2003, 131:599-606.
54. Lo Fo Wong D.M.A., Dahl J., Stege H., van der Wolf P.J., Leontides L., von Altrock A., et al. Herd-level risk factors for subclinical Salmonella infection in European finishing-pig herds. Preventive Veterinary Medicine 2004, 62:253-266.
55. Lo Fo Wong D.M.A., Dahl J., van der Wolf P.J., Wingstrand A., Leontides L., von Altrock A. Recovery of Salmonella enterica from seropositive finishing pig herds. Veterinary Microbiology 2003, 97:201-214.
56. Loynachan A.T., Nugent J.M., Erdman M.M., Harris D.L. Acute infection of swine by various Salmonella serovars. Journal of Food Protection 2004, 67(7):1484-1488.
57. Majowicz S.E., Musto J., Scallan E., Angulo F.J., Kirk M., O'Brien S.J., et al. The global burden of nontyphoidal Salmonella gastroenteritis. Clinical Infectious Diseases 2010, 50(6):882-889.
58. Mannion C., Egan J., Lynch B.P., Fanning S., Leonard N. An investigation into the efficacy of washing trucks following the transportation of pigs-A Salmonella perspective. Foodborne Pathogens and Disease 2008, 5(3):261-271.
59. Mikkelsen L.L., Naughton P.J., Hedemann M.S., Jensen B.B. Effects of physical properties of feed on microbial ecology and survival of Salmonella enterica serovar Typhimurium in the pig gastrointestinal tract. Applied and Environmental Microbiology 2004, 70(6):3485-3492.
60. Miller G.Y., Liu X., McNamara P.E., Barber D.A. Influence of Salmonella in pigs preharvest and during pork processing on human health costs and risks from pork. Journal of Food Protection 2005, 68(9):1788-1798.
61. Molla B., Sterman A., Mathews J., Artuso-Ponte V., Abley M., Farmer W., et al. Salmonella enterica in commercial swine feed and subsequent isolation of phenotypically and genotypically related strains from fecal samples. Applied and Environmental Microbiology 2010, 76(21):7188-7193.
62. Moller K., Jensen T.K., Jorsal S.E., Leser T.D., Carstensen B. Detection of Lawsonia intracellularis, Serpulina hyodysenteriae, weakly beta-haemolytic intestinal spirochaetes, Salmonella enterica, and haemolytic Escherichia coli from swine herds with and without diarrhea among growing pigs. Veterinary Microbiology 1998, 62:59-72.
63. Mousing J., Jensen P.T., Halgaard C., Bager F., Feld N., Nielsen B., et al. Nation-wide Salmonella enterica surveillance and control in Danish slaughter swine herds. Preventive Veterinary Medicine 1997, 29:247-261.
64. Nielsen B., Baggesen D., Bager F., Haugegaard J., Lind P. The serological response to Salmonella serovars typhimurium and infantis in experimentally infected pigs. The time course followed with an indirect anti-LPS ELISA and bacteriological examinations. Veterinary Microbiology 1995, 47(3-4):205-218.
65. Nollet N., Maes D., De Zutter L., Duchateau L., Houf K., Huysmans K., et al. Risk factors for the herd-level bacteriologic prevalence of Salmonella in Belgian slaughter pigs. Preventive Veterinary Medicine 2004, 65:63-75.
66. Oliveira C.J., Carvalho L.F.O.S., Fernandes S.A., Tavechio A.T., Domingues F.J. Prevalence of pigs infected by Salmonella typhimurium at slaughter after an enterocolitis outbreak. International Journal of Food Microbiology 2005, 105:267-271.
67. Oliveira C.J., Carvalho L.F., Garcia T.B. Experimental airborne transmission of Salmonella Agona and Salmonella Typhimurium in weaned pigs. Epidemiology and Infection 2006, 134:199-209.
68. Oliveira C.J., Garcia T.B., Carvalho L.F., Givisiez P.E. Nose-to-nose transmission of Salmonella Typhimurium between weaned pigs. Veterinary Microbiology 2007, 125:355-361.
69. Osterberg J., Lewerin S.S., Wallgren P. Patterns of excretion and antibody responses of pigs inoculated with Salmonella Derby and Salmonella Cubana. The Veterinary Record 2009, 165(14):404-408.
70. Osterberg J., Wallgren P. Effects of a challenge dose of Salmonella Typhimurium or Salmonella Yoruba on the patterns of excretion and antibody responses of pigs. The Veterinary Record 2008, 162(18):580-586.
71. Poljak Z., Dewey C.E., Friendship R.M., Martin S.W., Christensen J. Multilevel analysis of risk factors for Salmonella shedding in Ontario finishing pigs. Epidemiology and Infection 2008, 136:1388-1400.
72. Proux K., Cariolet R., Fravalo P., Houdayer C., Keranflech A., Madec F. Contamination of pigs by nose-to-nose contact or airborne transmission of Salmonella Typhimurium. Veterinary Research 2001, 32:591-600.
73. Rajic A., Chow E.Y.W., Wu J.T.Y., Deckert A.E., Reid-Smith R., Manninen K., et al. Salmonella infections in ninety Alberta swine finishing farms: Serological prevalence, correlation between culture and serology, and risk factors for infection. Foodborne Pathogens and Disease 2007, 4:169-177.
74. Rajic A., O'Connor B.P., Deckert A.E., Keenliside J., McFall M.E., Reid-Smith R.J., et al. Farm-level risk factors for the presence of Salmonella in 89 Alberta swine-finishing barns. Canadian Journal of Veterinary Research 2007, 71:264-270.
75. Rajkowski K.T., Eblen S., Laubauch C. Efficacy of washing and sanitizing trailers used for swine transport in reduction of Salmonella and Escherichia coli. Journal of Food Protection 1998, 61(1):31-35.
76. Rostagno M.H. Can stress in farm animals increase food safety risk?. Foodborne Pathogens and Disease 2009, 6(7):767-776.
77. Rostagno M.H., Hurd H.S., McKean J.D. Salmonella enterica prevalence and serotype distribution in swine at slaughter. Proceedings of the 7th International Symposium on the Epidemiology & Control of Foodborne Pathogens in Pork 2007, 153-155.
78. Rostagno M.H., Hurd H.S., McKean J.D. Split marketing as a risk factor for Salmonella enterica infection in swine. Foodborne Pathogens and Disease 2009, 6(7):865-869.
79. Rostagno M.H., Hurd H.S., McKean J.D., Ziemer C.J., Gailey J.K., Leite R.C. Preslaughter holding environment in pork plants is highly contaminated with Salmonella enterica. Applied and Environmental Microbiology 2003, 69(8):4489-4494.
80. Rostagno M.H., Eicher S.D., Lay D.C. Immunological, physiological, and behavioral effects of Salmonella enterica carriage and shedding in experimentally infected finishing pigs. Foodborne Pathogens and Disease 2011, 8(5):623-630.
81. Rostagno, M. H., Hurd, H. S., & McKean, J. D. (in press). Variation of bacteriologic and serologic Salmonella enterica prevalence between cohorts within finishing swine production farms. Food Research International, doi:10.1016/j.foodres.2011.01.062.
82. Sanchez J., Dohoo I.R., Christensen J., Rajic A. Factors influencing the prevalence of Salmonella spp. in swine farms: A meta-analysis approach. Preventive Veterinary Medicine 2007, 81:148-177.
83. Scallan E., Hoekstra R.M., Angulo F.J., Tauxe R.V., Widdowson M.A., Roy S.L., et al. Foodborne illness acquired in the United States-Major pathogens. Emerging Infectious Diseases 2011, 17(1):7-15.
84. Scherer K., Szabo I., Rosler U., Appel B., Hensel A., Nockler K. Time course of infection with Salmonella Typhimurium and its influence on fecal shedding, distribution in inner organs, and antibody response in fattening pigs. Journal of Food Protection 2008, 71(4):699-705.
85. Snary E.L., Munday D.K., Arnold M.E., Cook A.J.C. Zoonoses action plan Salmonella monitoring programme: An investigation of the sampling protocol. Journal of Food Protection 2010, 73(3):488-494.
86. Srinand S., Robinson R.A., Collins J.E., Nagaraja K.V. Serologic studies of experimentally induced Salmonella Choleraesuis var kunzendorf infection in pigs. American Journal of Veterinary Research 1995, 56(9):1163-1168.
87. Steenhard N.R., Jensen T.K., Baggesen D.L., Roepstorff A., Moller K. Excretion in feces and mucosal persistence of Salmonella ser. Typhimurium in pigs subclinically infected with Oesophagostomum spp. American Journal of Veterinary Research 2002, 63(1):130-136.
88. Stege H., Christensen J., Nielsen J.P., Baggesen D.L., Enoe C., Willeberg P. Prevalence of subclinical Salmonella enterica infection in Danish finishing pig herds. Preventive Veterinary Medicine 2000, 44:175-188.
89. Swanenburg M., Urlings H.A., Keuzenkamp D.A., Snijders J.M. Salmonella in the lairage of pig slaughterhouses. Journal of Food Protection 2001, 64(1):12-16.
90. Thakur S., Tadesse D.A., Morrow M., Gebreyes W.A. Occurrence of multidrug resistant Salmonella in antimicrobial-free (ABF) swine production systems. Veterinary Microbiology 2007, 125(3-4):362-367.
91. van der Wolf P.J., Bongers J.H., Elbers A.R.W., Franssen F.M.M.C., Hunneman W.A., van Exsel A.C.A., et al. Salmonella infections in finishing pigs in The Netherlands: Bacteriological her prevalence, serogoup and antibiotic resistance of isolates and risk factors for infection. Veterinary Microbiology 1999, 67:263-275.
92. van der Wolf P.J., Wolbers W.B., Elbers A.R.W., van der Heijden H.M.J.F., Koppen J.M.C.C., Hunneman W.A., et al. Herd level husbandry factors associated with the serological Salmonella prevalence in finishing pig herds in The Netherlands. Veterinary Microbiology 2001, 78:205-219.
93. van Duijkeren E., Wannet W.J.B., Houwers D.J., van Pelt W. Serotype and phage type distribution of Salmonella strains isolated from humans, cattle, pigs, and chickens in The Netherlands from 1984 to 2001. Journal of Clinical Microbiology 2002, 40(11):3980-3985.
94. van Winsen R.L., van Nes A., Keuzenkamp D., Urlings H.A., Lipman L.J., Biesterveld S., et al. Monitoring of transmission of Salmonella enterica serovars in pigs using bacteriological and serological detection methods. Veterinary Microbiology 2001, 80(3):267-274.
95. Varga C., Rajic A., McFall M.E., Reid-Smith R.J., McEwen S.A. Associations among antimicrobial use and antimicrobial resistance of Salmonella spp. isolates from 60 Alberta finishing swine farms. Foodborne Pathogens and Disease 2009, 6(1):23-31.
96. Vieira-Pinto M., Tenreiro R., Martins C. Unveiling contamination sources and dissemination routes of Salmonella sp. in pigs at a Portuguese slaughterhouse through macrorestriction profiling by pulsed-field electrophoresis. International Journal of Food Microbiology 2006, 110(1):77-84.
97. Warriss P.D. Optimal lairage times and conditions for slaughter pigs: A review. The Veterinary Record 2003, 153(6):170-176.
98. Wegener H.C. Danish initiatives to improve the safety of meat products. Meat Science 2010, 84:276-283.
99. Wilkins W., Rajic A., Waldner C., McFall M., Chow E., Muckle A., et al. Distribution of Salmonella serovars in breeding, nursery, and grow-to-finish pigs, and risk factors for shedding in ten farrow-to-finish swine farms in Alberta and Saskatchewan. Canadian Journal of Veterinary Research 2010, 74:81-90.
100. Wills R.W., Gray J.T., Fedorka-Cray P.J., Yoon K.J., Ladely S., Zimmerman J.J. Synergism between porcine reproductive and respiratory syndrome virus (PRRSV) and Salmonella choleraesuis in swine. Veterinary Microbiology 2000, 71:177-192.
101. Wood R.L., Pospichil A., Rose R. Distribution of persistent Salmonella typhimurium infection in internal organs of swine. American Journal of Veterinary Research 1989, 50(7):1015-1021.
102. Wood R.L., Rose R., Coe N.E., Ferris K.E. Experimental establishment of persistent infection in swine with a zoonotic strain of Salmonella Newport. American Journal of Veterinary Research 1991, 52(6):813-819.
103. Zheng D.M., Bonde M., Sorensen J.T. Associations between the proportion of Salmonella seropositive slaughter pigs and the presence of herd level risk factors for introduction and transmission of Salmonella in 34 Danish organic, outdoor (non-organic) and indoor finishing-pig farms. Livestock Science 2007, 106:189-199.