Hostname: page-component-848d4c4894-ndmmz Total loading time: 0 Render date: 2024-05-01T12:41:11.268Z Has data issue: false hasContentIssue false
  • English
  • Français

Empirical and theoretical evidence for herd size as a risk factor for swine diseases

Published online by Cambridge University Press:  09 March 2007

Ian A. Gardner ,
Preben Willeberg  and
Jan Mousing
Ian A. Gardner*
Affiliation:
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
Preben Willeberg
Affiliation:
Danish Veterinary and Food Administration, Mørkhøj Bygade 19, DK-2760 Søborg, Denmark Danish Bacon and Meat Council, Axelborg, Axeltorv 3, DK-1609 Copenhagen V, Denmark
Jan Mousing
Affiliation:
Danish Bacon and Meat Council, Axelborg, Axeltorv 3, DK-1609 Copenhagen V, Denmark
*
*Corresponding author E-mail: iagardner@ucdavis.edu
Get access Rights & Permissions [Opens in a new window]

Abstract

Herd size is frequently studied as a risk factor for swine diseases, yet the biological rationale for a reported association with herd size (whether positive or negative) is rarely adequately discussed in published epidemiological studies. Biologically plausible reasons for a positive association between herd size and disease include a greater risk of introduction of pathogens from outside the herd, greater risk of transmission of pathogens within and among herds when the herd is large, and effects of management and environmental factors that are related to herd size. However, compared with owners of small herds, owners of large herds might more frequently adopt management and housing practices that mitigate this theoretically increased risk. We used studies of pleuritis, pneumonia and pseudorabies to describe the epidemiological issues involved in evaluations of the relationship between management factors, herd size and disease. In future studies, we recommend that (i) herd size be measured in a way that best characterizes the true population at risk; (ii) studies that evaluate management-related risk factors should account for herd size wherever possible; (iii) population-based studies of the interrelationships among management factors and between management factors, herd size, herd density and pig density be done; (iv) likely biological reasons for any herd-size effect be postulated; and (v) the distribution of herd sizes in the source population and the study sample be described.

Type
Research Article
Information
Animal Health Research Reviews , Volume 3 , Issue 1 , June 2002 , pp. 43 - 55
Copyright
Copyright © CAB International 2002

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Aalund, O, Willeberg, P, Mandrup, M and Riemann, HP (1976) Lung lesions at slaughter: associations to factors in the pig herd. Nordisk Veterinaermedicin 28, 487–495.Google ScholarPubMed
Abiver, N, Seegers, H, Beaudeau, F, Laval, A and Fourichon, C (1998) Risk factors for high sow mortality in French swine herds. Preventive Veterinary Medicine 33, 109–119.CrossRefGoogle Scholar
Andersen, H (1981) Studies of the relationships between herd-size, the percentage of pigs culled during the finishing period and the prevalence rate at slaughter of pigs with lesions. Nordisk Veterinaermedicin 33, 413–416.Google ScholarPubMed
Anderson, RM and May, RM (1982) Directly transmitted infectious diseases: control by vaccination. Science 215, 1053–1060.CrossRefGoogle ScholarPubMed
Anderson, PL, Morrison, RB, Molitor, TW and Thawley, DG (1990) Factors associated with circulation of pseudorabies virus within swine herds. Journal of the American Veterinary Medical Association 196, 877–880.CrossRefGoogle ScholarPubMed
Assadi-Rad, AM, New, JC and Patton, S (1995) Risk factors associated with the transmission of Toxoplasma gondii to sows kept in different management systems in Tennessee. Veterinary Parasitology 57, 289–297.CrossRefGoogle ScholarPubMed
Austin, CC, Weigel, RM, Hungerford, LL and Biehl, LG (1993) Factors affecting the risk of infection with pseudorabies virus in Illinois swine herds. Preventive Veterinary Medicine 17, 161–173.CrossRefGoogle Scholar
Bäckström, L (1973) Environment and animal health in piglet production. A field study of incidences and correlations Acta Veterinaria Scandinavica (upplementum) 41: 1–240.Google Scholar
Bäckström, L and Bremer, H (1978) The relationship between disease incidences of fatteners registered at slaughter and environmental factors in herds. Nordisk Veterinaermedicin 30, 526–533.Google ScholarPubMed
Bäckström, L, Morkoc, AC, Connor, J, Larson, R and Price, W (1984) Clinical study of mastitis-metritis-agalactia in sows in Illinois. Journal of the American Veterinary Medical Association 185, 70–73.Google ScholarPubMed
Benard, HJ, Stärk, KD, Morris, RS, Pfeiffer, DJ and Moser, H (1999) The 1997–1998 classical swine fever epidemic in The Netherlands—a survival analysis. Preventive Veterinary Medicine 42, 235–248.CrossRefGoogle ScholarPubMed
Boelaert, F, Deluyker, H, Maes, D, Godfroid, J, Raskin, A, Varewijck, H, Pensaert, M, Nauwynck, H, Castryck, F, Miry, C, Robijns, JM, Hoet, B, Segers, E, Van Vlaenderen, I, Robert, A and Koenen, F (1999) Prevalence of herds with young sows seropositive to pseudorabies (Aujeszky's disease) in Northern Belgium. Preventive Veterinary Medicine 41, 239–255.CrossRefGoogle ScholarPubMed
Bouma, A, de Jong, MCM and Kimman, TG (1995) Transmission of pseudorabies virus within pig populations is independent of the size of the population. Preventive Veterinary Medicine 23, 163–172.CrossRefGoogle Scholar
Buddle, JR, Mercy, AR, Skirrow, SZ, Madec, F and Nicholls, RR (1997) Epidemiological studies of pig diseases: 1. Use of French protocols for risk factor assessment to predict the health status of Australian herds. Australian Veterinary Journal 75: 274–281.CrossRefGoogle ScholarPubMed
Carstensen, B and Christensen, J (1998) Herd size and sero-prevalence of Salmonella enterica in Danish swine herds: a random-effects model for register data. Preventive Veterinary Medicine 34, 191–203.CrossRefGoogle ScholarPubMed
Christensen, G and Mousing, J (1992) Respiratory system. In: Leman, et al. (editors). In Diseases of Swine. pp Ames (IA): Iowa State University Press: pp. 138–162.Google Scholar
Christensen, G, Vraa-Andersen, L and Mousing, J (1995) Causes of mortality among sows in Danish pig herds. Veterinary Record 137, 395–399.CrossRefGoogle ScholarPubMed
Christensen, J (1996) The influence of selected litter and herd factors on treatments for lameness in suckling piglets from 35 Danish herds. Preventive Veterinary Medicine 26, 107–118.CrossRefGoogle Scholar
Christensen, J and Gardner, IA (2000) Herd-level interpretation of test results for epidemiologic studies of animal diseases. Preventive Veterinary Medicine 45, 83–106.CrossRefGoogle ScholarPubMed
Christensen, LS, Mousing, J, Mortensen, S, Sørensen, KJ, Standbygaard, SB, Henriksen, CA and Andersen, JB (1990) Evidence of long distance airborne transmission of Aujeszky's disease (pseudorabies) virus. Veterinary Record 127, 471–474.Google ScholarPubMed
Cutler, RS, Molitor, TW, Leman, AD and Werdin, RE (1983) Farm studies of porcine parvovirus infection. Journal of the American Veterinary Medical Association 182, 592–594.Google ScholarPubMed
Dangolla, A, Willeberg, P, Bjørn, H and Roepstorff, A (1996) Associations of Ascaris suum and Oesophagostomum spp. infections of sows with management factors in 83 Danish sow herds. Preventive Veterinary Medicine 27, 197–209.CrossRefGoogle Scholar
De Jong, MCM (1995) Mathematical modelling in veterinary epidemiology: why model building is important. Preventive Veterinary Medicine 25, 183–193.CrossRefGoogle Scholar
Dewey, CE, Wittum, TE, Hurd, HS, Dargatz, DA and Hill, GW (1995) Herd- and litter-level factors associated with the incidence of diarrhea morbidity and mortality in piglets 4–14 days of age. Journal of Swine Health and Production 3, 105–112.Google Scholar
Dohoo, IR, Ducrot, C, Fourichon, C, Donald, A and Hurnik, D (1997) An overview of techniques for dealing with large numbers of independent variables in epidemiologic studies. Preventive Veterinary Medicine 29, 221–239.CrossRefGoogle ScholarPubMed
Done, SH (1991) Environmental factors affecting the severity of pneumonia in pigs. The Veterinary Record 128, 582–586.CrossRefGoogle ScholarPubMed
Duffy, SJ, Morrison, RB and Thawley, DG (1991) Spread of pseudorabies virus among breeding swine in quarantined herds. Journal of the American Veterinary Medical Association 199, 61–65.CrossRefGoogle ScholarPubMed
Duffy, SJ, Morrison, RB and Thawley, DG (1991) Factors associated with spread of pseudorabies virus among breeding swine in quarantined herds. Journal of the American Veterinary Medical Association 199, 66–70.CrossRefGoogle ScholarPubMed
Elbers, AR (1991). The use of slaughterhouse information in monitoring systems for herd health control in pigs. PhD thesis, University of Utrecht, The Netherlands, 152 pp.Google Scholar
Elbers, AR, Stegeman, JA and de Jong, MCM (2001) Factors associated with the introduction of classical swine fever virus into pig herds in the central area of the 1997/98 epidemic in the Netherlands. Veterinary Record 149, 377–382.CrossRefGoogle ScholarPubMed
Flesjå, KI and Solberg, I (1981) Pathological lesions in swine at slaughter. IV. Pathological lesions in relation to rearing system and herd-size. Acta Veterinaria Scandinavica 22, 272–282.Google ScholarPubMed
Flesjå, KI, Forus, IB and Solberg, I (1982) Pathological lesions in swine at slaughter. V. Pathological lesions in relation to some environmental factors in the herds. Acta Veterinaria Scandinavica 23, 169–183.CrossRefGoogle Scholar
Flori, J, Mousing, J, Gardner, I, Willeberg, P and Have, P (1995) Risk factors associated with seropositivity to porcine respiratory coronavirus in Danish swine herds. Preventive Veterinary Medicine 25, 51–62.CrossRefGoogle Scholar
Fox, JP, Elveback, L, Scott, W, Gatewood, L and Ackerman, E (1971) Herd immunity: basic concept and relevance to public health immunization practices. American Journal of Epidemiology 94, 179–189.CrossRefGoogle ScholarPubMed
Frost, WH (1976) Some conceptions of epidemics in general. American Journal of Epidemiology 103, 141–151.CrossRefGoogle ScholarPubMed
Greenland, S (1989) Modeling and variable selection in epidemiologic analysis. American Journal of Public Health 79, 340–349.CrossRefGoogle ScholarPubMed
Greenland, S and Neutra, R (1980) Control of confounding in the assessment of medical technology. International Journal of Epidemiology 9, 361–367.CrossRefGoogle ScholarPubMed
Henningsen, D, Mousing, J and Aalund, O (1988) Porcine corona virus (PCV) in Denmark: an epidemiological study based on questionnaire data from screening districts. Dansk Veterinaertidsskrift 71, 1168–1177.Google Scholar
Hurnik, D, Dohoo, IR and Bate, LA (1994) Types of farm management as risk factors for swine respiratory disease. Preventive Veterinary Medicine 20, 147–157.CrossRefGoogle Scholar
Hunneman, WA (1986) Incidence, economic effects and control of Haemophilus pleuropneumoniae infections in pigs. Veterinary Quarterly 8, 83–87.CrossRefGoogle ScholarPubMed
Koketsu, Y (2000) Retrospective analysis of trends and production factors associated with sow mortality on swine-breeding farms in USA. Preventive Veterinary Medicine 46, 249–256.CrossRefGoogle ScholarPubMed
Koopman, JS and Longini, IM (1994) The ecological effects of individual exposure and non-linear disease dynamics in populations. American Journal of Public Health 84, 836–842.CrossRefGoogle Scholar
Leontides, L, Ewald, C, Mortensen, S and Willeberg, P (1994) Factors associated with the circulation of Aujeszky's disease virus in fattening herds of an intensively vaccinated area of Northern Germany. Preventive Veterinary Medicine 20, 63–78.CrossRefGoogle Scholar
Leontides, L, Ewald, C and Willeberg, P (1994) Herd risk factors for serological evidence of Aujeszky's disease virus infection of breeding sows in Northern Germany (1990–1991). Journal of Veterinary Medicine Series B 41, 554–560.CrossRefGoogle ScholarPubMed
Leontides, L, Ewald, C, Mortensen, S and Willeberg, P (1995) Factors associated with the seroprevalence of Aujeszky's disease virus in seropositive breeding herds of Northern Germany during area-wide compulsory vaccination. Preventive Veterinary Medicine 23, 73–85.CrossRefGoogle Scholar
Lindqvist, J (1974) Animal health and environment in the production of fattening pigs. Acta Veterinaria Scandinavica 51, 1–78.Google Scholar
Lingaas, F (1991) Epidemiological and genetical studies in Norwegian pig herds. III. Herd effects. Acta Veterinaria Scandinavica 32, 97–105.CrossRefGoogle ScholarPubMed
Maes, D, Deluyker, H, Verdonck, M, Castryck, F, Miry, C, Vrijens, B and de Kruif, A (1999) Risk indicators for the seroprevalence of Mycoplasma hyopneumoniae, porcine influenza viruses and Aujeszky's disease virus in slaughter pigs from fattening pig herds. Journal of Veterinary Medicine Series B 46, 341–352.CrossRefGoogle ScholarPubMed
Maes, D, Deluyker, H, Verdonck, M, Castryck, F, Miry, C, Vrijens, B and de Kruif, A (2000) Herd factors associated with the seroprevalences of four major respiratory pathogens in slaughter pigs from farrow-to-finish pig herds. Veterinary Research 31, 313–327.CrossRefGoogle ScholarPubMed
Maes, DG, Deluyker, H, Verdonck, M, Castryck, F, Miry, C, Vrijens, B, Ducatelle, R and de Kruif, A (2001) Non-infectious factors associated with macroscopic and microscopic lung lesions in slaughter pigs from farrow-to-finish herds. Veterinary Record 148, 41–46.CrossRefGoogle ScholarPubMed
Manuel-León, A and Casal, J (2001) Application of a probabilistic approach to the risk assessment of virus airborne transmission. Veterinary Record 148, 574–575.CrossRefGoogle Scholar
Marchevsky, N, Held, JR and Garcia-Carrillo, C (1989) Probability of introducing diseases because of false negative test results. American Journal of Epidemiology 130, 611–614.CrossRefGoogle ScholarPubMed
Martin, SW, Shoukri, M and Thorburn, MA (1992) Evaluating the health status of herds based on tests applied to individuals. Preventive Veterinary Medicine 14, 33–43.CrossRefGoogle Scholar
Martinsson, K and Lundeheim, N (1988) Inspection findings in slaughter pigs. The effects of the type of operation and the size of the herd and the barn. Svensk Veterinartidning 40, 313–319.Google Scholar
Morrison, RB, Marsh, WE, Anderson, PL and Thawley, DG (1991) Factors associated with the seroprevalence of pseudorabies virus in breeding swine from quarantined herds. Journal of the American Veterinary Medical Association 199, 580–583.CrossRefGoogle ScholarPubMed
Mousing, J, Lybye, H, Barfod, K, Meyling, A, Rønsholt, L and Willeberg, P (1990) Chronic pleuritis in pigs for slaughter: an epidemiological study of infectious and rearing system-related risk factors. Preventive Veterinary Medicine 9, 107–119.CrossRefGoogle Scholar
Mousing, J, Mortensen, S, Ewald, C and Christensen, LS (1991) Epidemiological and meteorological aspects of Aujeszky's disease in Denmark and Northern Germany. In: Thrusfield, M (editor). Proceedings, Society for Veterinary Epidemiology and Preventive Medicine,London, pp. 18–26.Google Scholar
Mousing, J, Permin, A, Mortensen, S, Bøtner, A and Willeberg, P (1997) A case–control questionnaire survey of risk factors for porcine reproductive and respiratory syndrome (PRRS) seropositivity in Danish swine herds. Veterinary Microbiology 55, 323–328.CrossRefGoogle ScholarPubMed
Pointon, AM, Heap, P and McCloud, P (1985) Enzootic pneumonia of pigs in South Australia—factors relating to incidence of disease. Australian Veterinary Journal 62, 98–101.CrossRefGoogle ScholarPubMed
Pritchard, GC (1982) Observations on clinical aspects of transmissible gastroenteritis of pigs in Norfolk and Suffolk, 1980–81. Veterinary Record 110, 465–469.CrossRefGoogle ScholarPubMed
Pritchard, GC (1987) Transmissible gastroenteritis in endemically infected breeding herds of pigs in East Anglia, 1981–1985. Veterinary Record 120, 226–230.CrossRefGoogle Scholar
Roepstorff, A and Jorsal, SE (1990) Relationship of the prevalence of swine helminths to management practices and anthelmintic treatment in Danish sow herds. Veterinary Parasitology 36, 245–257.CrossRefGoogle ScholarPubMed
Savitz, DA (1992) Measurements, estimates, and inferences in reporting epidemiologic study results. American Journal of Epidemiology 135, 223–224.CrossRefGoogle ScholarPubMed
Siegel, AM and Weigel, RM (1999) Herd factors affecting the selection and success of intervention strategies in the program for eradication of pseudorabies (Aujeszky's disease) virus from Illinois swine farms. Preventive Veterinary Medicine 40, 243–259.CrossRefGoogle ScholarPubMed
Siegel, AM, Weigel, RM and Taft, AC (1993) Factors associated with time under quarantine for swine herds in the voluntary phase of the Illinois pseudorabies eradication program. Preventive Veterinary Medicine 16, 295–310.CrossRefGoogle Scholar
Smith, G and Grenfell, BT (1990) Population biology of pseudorabies in swine. American Journal of Veterinary Research 51, 148–155.CrossRefGoogle ScholarPubMed
Stärk, KDC, Pfeiffer, DU and Morris, RS (1998) Risk factors for respiratory diseases in New Zealand pig herds. New Zealand Veterinary Journal 46, 3–10.CrossRefGoogle ScholarPubMed
Stege, H, Christensen, J, Nielsen, JP and Willeberg, P (2001) Data-quality issues and alternative variable-screening methods in a questionnaire-based study on subclinical Salmonella enterica infection in Danish pig herds. Preventive Veterinary Medicine 48, 35–54.CrossRefGoogle Scholar
Stegeman, A, Elbers, ARW, Smak, J and de Jong, MCM (1999) Quantification of the transmission of classical swine fever virus between herds during the 1997–1998 epidemic in The Netherlands. Preventive Veterinary Medicine 42, 219–234.CrossRefGoogle ScholarPubMed
Strom, JS (1978). Heat loss from swine and poultry as basis for design of environmental control systems in livestock buildings. Statens Byggeforskningsinstitut, pp. 46–47.Google Scholar
Svensmark, B, Jorsal, SE, Nielsen, K and Willeberg, P (1989) Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. I. Pre-weaning diarrhoea. Acta Veterinaria Scandinavica 30, 43–53.CrossRefGoogle ScholarPubMed
Svensmark, B, Nielsen, K, Willeberg, P and Jorsal, SE (1989) Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. II. Post-weaning diarrhoea. Acta Veterinaria Scandinavica 30, 55–62.CrossRefGoogle ScholarPubMed
Thorburn, MA, McDermott, JJ and Martin, SW (1991) Letter to the editor: re. Probability of introducing diseases because of false negative test results. American Journal of Epidemiology 133, 321–322.CrossRefGoogle Scholar
Tuovinen, VK, Gröhn, YT, Straw, BE and Boyd, RD (1992) Feeder unit environmental factors associated with partial condemnations in market swine. Preventive Veterinary Medicine 12, 175–195.CrossRefGoogle Scholar
United States Department of Agriculture: Animal and Plant Health Inspection Service: Veterinary Services (1992). National Swine Survey. Data Collection 1990. Technical Report. Fort Collins (CO): United States Department of Agriculture.Google Scholar
United States Department of Agriculture: Animal and Plant Health Inspection Service: Veterinary Services (1995). Swine ‘95. Part 1: Reference of 1995 swine management practices. Fort Collins (CO), p. 12.Google Scholar
van der Wolf, PJ, Wolbers, WB, Elbers, AR, van der Heijden, HM, Koppen, JM, Hunneman, WA, van Schie, FW and Tielen, MJ (2001) Herd level husbandry factors associated with the serological Salmonella prevalence in finishing pig herds in The Netherlands. Veterinary Microbiology 78, 205–219.CrossRefGoogle ScholarPubMed
Weigel, RM, Austin, CC, Siegel, AM, Biehl, LG and Taft, AC (1992) Risk factors associated with the seroprevalence of pseudorabies virus in Illinois swine herds. Preventive Veterinary Medicine 12, 1–13.CrossRefGoogle Scholar
Weigel, RM, Dubey, JP, Siegel, AM, Kitron, UD, Mannelli, A, Mitchell, MA, Mateus-Pinilla, NE, Thulliez, P, Shen, SK, Kwok, OC and Todd, KS (1995) Risk factors for transmission of Toxoplasma gondii on swine farms in Illinois. Journal of Parasitology 81, 736–741.CrossRefGoogle ScholarPubMed
Willeberg, P (1979) The Danish Swine Slaughter Inspection Data Bank and some epidemiologic applications. Proceedings of International Symposium on Animal Health and Disease Data Banks.Washington (DC):USDA. Miscellaneous publication 1381, pp. 133–145.Google Scholar
Willeberg, P, Gardner, IA, Mortensen, S and Mousing, J (1994) Models of herd-size effects in swine diseases. Kenya Veterinarian 18, 189–191.Google Scholar
Wilson, MR, Friendship, RM, McMillan, I, Hacker, RR, Pieper, R and Swaminathan, S (1986) A survey of productivity and its component interrelationships in Canadian swine herds. Journal of Animal Science 62, 576–582.CrossRefGoogle Scholar
Wittum, TE, Dewey, CE, Hurd, HS, Dargatz, DA and Hill, GW (1995) Herd- and litter-level factors associated with the incidence of diarrhea morbidity and mortality in piglets 1 to 3 days of age. Journal of Swine Health and Production 3, 99–104.Google Scholar
Yanga, ST, Gardner, IA, Hurd, HS, Eernisse, KA and Willeberg, P (1995) Management and demographic factors associated with seropositivity to transmissible gastroenteritis virus in US swine herds, 1989–1990. Preventive Veterinary Medicine 24, 213–228.CrossRefGoogle Scholar
Yorke, JA, Nathanson, N, Pianigiani, G, and Martin, J (1979) Seasonality and the requirements for perpetuation and eradication of viruses in populations. American Journal of Epidemiology 109, 103–123.CrossRefGoogle ScholarPubMed
Zimmerman, JJ, Dreesen, DW, Owen, WJ and Beran, GW (1990) Prevalence of toxoplasmosis in swine from Iowa. Journal of the American Veterinary Medical Association 196, 266–270.CrossRefGoogle ScholarPubMed
Zimmerman, JJ, Owen, WJ, Hill, HT and Beran, GW (1991) Seroprevalence of antibodies against encephalomyocarditis virus in swine of Iowa. Journal of the American Veterinary Medical Association 199, 1737–1741.CrossRefGoogle ScholarPubMed