Herd-level risk factors for subclinical Salmonella infection in European finishing-pig herds

Wong, Danilo Lo Fo; Dahl, Jan; Stege, Helle; Wolf, P.J. van der; Leontides, Leonidas; Altrock, Alexandra von; Thorberg, B.-M.

doi:10.1016/j.prevetmed.2004.01.001

Cited by 132 publications

(143 citation statements)

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“…The previous analytical studies carried out to determine risk factors for Salmonella infection of market-age pigs were cross-sectional [26] or case-control studies [6,14,18,28]. Such studies are very efficient, inexpensive and quick [27] but time sequence between the risk factors and the outcome is in such study design often difficult to assess, especially when exposure factors are not time-invariant [8].…”

Section: Discussionmentioning

confidence: 99%

“…Serological response to Salmonella serotypes in pigs is assessed by Calibrated Optical Density (COD) results of indirect anti-lipopolysaccharide ELISA tests [21,22]. The sero-epidemiologic studies were case-control [26] or retrospective crosssectional [6,14,16,18,28] studies. The aims of those studies were to identify, mainly at the herd level, risk factors associated with the detection of antibodies against Salmonella in finishing pigs.…”

Section: Introductionmentioning

confidence: 99%

“…The main factors influencing Salmonella contamination of finishing pigs reported in those studies are related to (1) hygiene: washing hands [18]; (2) herd management: size of the herd [28], batch production system [18], and housing (type of pen partitions and wall separation) [18]; (3) feeding practices: groundness and pH of feed [18,28] and type of feeding (wet versus dry) [7,14]; (4) health disorders: parasite infestation [28], use of antibiotics [9,16,28] and health status of the herd [7]. Hypotheses of factors raised in the literature concern concurrent infections that might favour Salmonella infection, such as Lawsonia intracellularis [20] or porcine reproductive and respiratory syndrome virus (PRRSV) [31].…”

Section: Introductionmentioning

confidence: 99%

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Risk factors forSalmonellaseroconversion of fattening pigs in farrow-to-finish herds

et al. 2007

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-We did a prospective observational 9-month long study to quantify risk factors of managerial and hygiene practices, and pig-health status for Salmonella seroconversion of fattening pigs reared in subclinically infected French farrow-to-finish farms. During the fattening phase, 2 649 pigs belonging to the same batch of contemporary pigs, from 89 conventional farrow-to-finish farms were individually followed and regularly blood sampled on a monthly basis. Farm recruitment was based on the farmer's willingness to cooperate. Pig status was assessed using an indirect ELISA test. Evolution of the serological status was studied by means of survival analysis. A Cox proportionalhazards model, taking into account the clustering of animals at the farm level, was used to examine the effects of explanatory variables on the time to Salmonella seroconversion of pigs. Applying group level antibiotic treatment to the pigs during the fattening period (Hazard Ratio (HR) = 2.4; 95% CI: 1.7, 3.4) was identified as a risk factor for Salmonella seroconversion, as the presence of residual Salmonella contamination in the fattening pen before placing the pigs into the pens (HR = 1.9; 95% CI: 1.2, 2.9). Porcine reproductive and respiratory syndrome virus (PRRSV) seropositivity during the fattening period also indicated an increased hazard for seroconversion (HR = 1.6; 95% CI: 1.1, 2.5). The batch size was identified as a risk factor for Salmonella seroconversion: the higher the number of pigs was in the fattening room followed, the higher was the risk (HR +10pigs = 1.05 for a 10-pig increment; 95% CI: 1.03, 1.06). The biosecurity measures of wearing specific clothes before entering the facilities (HR = 0.5; 95% CI: 0.3, 0.9) and enclosing the pig farm facilities were protective (HR = 0.4; 95% CI: 0.2, 0.8).Salmonella / pigs / seroconversion / risk factors / survival analysis

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Risk factors forSalmonellaseroconversion of fattening pigs in farrow-to-finish herds

et al. 2007

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“…(Nordjylland and Sonderjylland) have large pig populations and generally larger farms. The association between herd size and Salmonella risk is complex: some studies report a positive association [9,21] negative [28] or no association [19,26]. Larger herds may have facilities that, in themselves, are sparing on Salmonella risk, e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Larger herds may have facilities that, in themselves, are sparing on Salmonella risk, e.g. feeding of fermented liquid feed [4,28] and improved biosecurity [13,19].…”

Section: Discussionmentioning

confidence: 99%

Descriptive spatial epidemiology of subclinicalSalmonellainfection in finisher pig herds: application of a novel method of spatially adaptive smoothing

Benschop

Hazelton²,

Stevenson³

et al. 2007

Vet. Res.

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-We describe the spatial epidemiological features of the 6.8 million meat-juice serological tests that were conducted between 1995 and 2004 as part of the Danish swine Salmonella control programme. We investigated pig and farm density using edge-corrected kernel estimations. Pigs were aggregated at the county level to assess county-level risk, and then we investigated farm-level risk by giving farms a case or non-case label using a cut-off of 40% of pigs positive. Conditional probability surfaces, correcting for the underlying population at risk, were produced for each year of the study period using a novel kernel estimator with a spatially adaptive smoothing bandwidth. This approach improves on previous methods by allowing focussed estimation of risk in areas of high population density while maintaining stable estimates in regions where the data are sparse. Two spatial trends in the conditional probability of a farm being a case were evident: (1) over the whole country, with the highest risk in the west compared to the east; and (2) on the Jutland peninsula with the highest risk in the north and south. At the farm-level a consistent area of risk was the south-west of Jutland. Case farms tended to aggregate indicating spatial dependency in the data. We found no association between pig or farm density and Salmonella risk. We generated hypotheses for this spatial pattern of risk and we conclude that this spatial pattern should be considered in the development of surveillance strategies and as a basis for further, more detailed analyses of the data.pigs / Salmonella / spatial epidemiology / Denmark / kernel smoothing

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2005

EFSA Journal

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The welfare of weaners and rearing pigs: effects of different space allowances and floor types _____________________________________________________ Opinion of the Scientific Panel on Animal Health and Welfare on a request from the Commission related to welfare of weaners and rearing pigs: effects of different space allowances and floor types _____________________________________________________ (Question N°EFSA-Q-2004-077) Adopted by the AHAW Panel on 13 th September 2005 Conclusions and recommendations on hygiene and public health aspects as indicated in relevant sections were adopted by the BIOHAZ panel of 8/9 June 2005 SUMMARY OF OPINION Council Directive 91/630/EEC laying down minimum standards for the protection of pigs has been amended by Council Directive 2001/88/EC, which foresees that the Commission will consider "appropriate legislative proposals on the effects of different space allowances and floor types applicable to the welfare of weaners and rearing pigs." In order to base these proposals on recent updated scientific knowledge, EFSA was invited by the European Commission to draw up an opinion on the welfare of weaners and rearing pigs, taking into account the effects of different space allowances and floor types. In addition to the animal health and welfare aspects the impact on the carcass should be assessed. The opinion was adopted by the Scientific Panel on animal Health and Welfare (AHAW) on 13 September 2005. The chapter on hygiene and public health aspects was jointly adopted by the Scientific Panel on Biological Hazards (BIOHAZ) Panel at its Plenary meeting held on 8/9 June 2005. According to the mandate of EFSA, ethical, socioeconomic , cultural and religious aspects are outside the scope of this Opinion. Evidence concerning pig behaviour and the extent of disease are important when the effects of space and flooring on pig welfare are considered. The behavioural repertoire of a pig includes standing, lying in various positions, walking to 7.

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Herd-level risk factors for subclinical Salmonella infection in European finishing-pig herds

Cited by 132 publications

References 25 publications

Risk factors forSalmonellaseroconversion of fattening pigs in farrow-to-finish herds

Risk factors forSalmonellaseroconversion of fattening pigs in farrow-to-finish herds

Descriptive spatial epidemiology of subclinicalSalmonellainfection in finisher pig herds: application of a novel method of spatially adaptive smoothing

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