Table 7.
Summary of risk factors for Salmonella enterica shedding on pig farms reported in 23 studies
| Risk factor of presence of Salmonella enterica | OR [90%CI] | Reference | ||
|---|---|---|---|---|
| Biosecurity measures and equipment | Cleaning measures and ‘empty and clean’ period Hygiene and clothes | Frequency of sow manure removal in farrowing rooms during the lacation period lower than once a day | 2.9 [1.2–6.7] | Beloeil et al., 2004a |
| Lack of emptying pits below slatted floors after removal of previous sows batches | 2.6 [1.1–6.4] | Fablet et al., 2003a; Beloeil et al., 2004a | ||
| Disinfection of rooms (without preliminary cleaning) is associated with a higher serological prevalence | 1.4* [1.1–1.9] | Van der Wolf et al., 2001 | ||
| Washing room without disinfection (risk factor concerning all enteric pathogens in swine) | 3.3* [1.1–9.7] | Pearce, 1999 | ||
| Residual Salmonella contamination of the room before loading of the batch followed | 3.1 [1.4–7.1] | Beloeil et al., 2004a | ||
| Duration of ‘empty and clean’ period lower than 6 days in farrowing room | 3.1* [1.7–5.5] | Beloeil et al., 2004a | ||
| Duration of ‘empty and clean’ period lower than 7 days in post‐weaning | 3.2 [1.3–8.2] | Fablet et al., 2003a | ||
| Duration of ‘empty and clean’ period lower than 3 days in fattening room | 2.0* [1.1–3.5] | Beloeil et al., 2004a | ||
| Detection of Salmonella on boots or environmental samples and/or lack of boot‐dip at the entrance of the facilities | NE | Letellier et al., 1999b;Rajic et al., 2005 | ||
| 2.1* [1.2–3.8] | Beloeil et al., 2004a | |||
| Lack of hand hygiene before tending to pigs; lack of toilet | 11.1* [1.8–70.2] | Funk et al., 2001b | ||
| 1.5* [1.1–2.1] | Lo Fo Wong et al., 2004 | |||
| Infection through people or equipment | More than two humans at finisher daily | 4.8* [1.4–17.1] | Funk et al., 2001b | |
| Allowing visitors with same day contact to other herds | 2.2 [1.3–3.9] | Bahnson et al., 2007 | ||
| Sharing equipment | NE† | Langvad et al., 2006 | ||
| Floors | Solid floors or straw on floors versus slatted floor | 1.5 [1.4–1.6] | Rossel et al., 2006 | |
| NE‡ | Hill et al., 2007 | |||
| Partially slatted floor versus fully slatted | 8.9* [5.0–15.9] | Nollet et al., 2004 | ||
| Pen separation | Pierced pen separation between batches or possibilities of snout contacts | 1.7 [1.1–2.6] | Lo Fo Wong et al., 2004 | |
| Feed and watering | Acidification or fermented liquid feed | No acidification of feed or water | 1.4* [1.3–1.6] | Rossel et al., 2006 |
| Use of dry or liquid feed in comparison with fermented liquid feed | 5.0* [2.8–8.9] | Van der Wolf et al., 2001 | ||
| Dry feed | Numerous studies have showed higher bacteriological or serological prevalences in pigs herds using dry feed versus herds using wet feed | 1.1* [0.2–6.8] | Kranker et al., 2001 | |
| 3.2 [1.4–7.1] | Beloeil et al., 2004a | |||
| 4.9 [1.9–12.7] | Bahnson et al., 2006b | |||
| 4.1* [1.4–12.2] | Farzan et al., 2006 | |||
| Pelleted feed | Serological prevalence is higher in pigs fed with pelleted ration versus wet or dry non‐pelleted ration | 4.2* [2.0–8.7] | Kranker et al., 2001 | |
| 12.5* [2.2–71.6] | Leontides et al., 2003 | |||
| 2.4* [1.5–3.7] | Lo Fo Wong et al., 2004 | |||
| 2.1 [1.2–3.8] | Bahnson et al., 2007 | |||
| No. feeds | Distribution of more than two kinds of feeds between post‐weaning and fattening period | NE§ | Fablet et al., 2003a | |
| Change in the feed diet during the follow‐up | 3.4 * [1.9–6.1] | Beloeil et al., 2004a | ||
| Drinker design | Bowl drinkers are associated with higher prevalence than nipple drinkers | 8.0 [3.4–19.0] | Bahnson et al., 2006b | |
| Herd management | Infection of sows | Infection of sow herds is associated with a higher serological prevalence in finishers | 3.2* [1.6–6.5] | Kranker et al., 2001 |
| Herd size | Risk of salmonella shedding seems to be associated with a higher herd size | NE | Baggesen et al., 1996; Carstensen and Christensen, 1998 | |
| 2.0 [1.3–3.0] | Bahnson et al., 2007 | |||
| 1.3* [1.0–1.7] | Kranker et al., 2001 | |||
| Herd type | Post‐weaning to fattening herds and fattening herds were more contaminated than farrow‐to‐finish herds | 1.6 [1.4–1.8] | Rossel et al., 2006 | |
| NE‡ | Clough et al., 2007 | |||
| Stocking density | Space allowance inferior to 0.75m2 per pig | 4.5* [1.3–15.7] | Funk et al., 2001b | |
| Gain of weight during fattening | Link between 10 kg gain of weight and Salmonella shedding | 1.2 [1.0–1.5] | Bahnson et al., 2007 | |
| Mixing batches | Mixing batches during the fattening period | 1.5 [1.4–1.6] | Rossel et al., 2006 | |
| Continuous production of pigs compared to all‐in/all‐out | 3.7* [2.1–6.4] | Lo Fo Wong et al., 2004 | ||
| 3.9* [1.4–10.5] | Farzan et al., 2006 | |||
| Origin of pigs | Recruitment of pigs from more than 3 different supplier herds | 3.3 [1.8–6.0] | Lo Fo Wong et al., 2004 | |
| Other breedings and contacts with domestic species or wild animals | Poultry breeding on the farm | 1.2 [1.1–1.3] | Rossel et al., 2006 | |
| Other domestic species at the site or indirect contacts with other herds | 4.7* [1.2–18.0] | Funk et al., 2001b | ||
| NE | Langvad et al., 2006 | |||
| Contact with rodents | NE | Le Moine et al., 1987; Letellier et al., 1999b | ||
| Health management | Antibiotic | Curative antibiotic treatment at the end of the fattening period | NE§ | Fablet et al., 2003b |
| Preventive antibiotic treatment during fattening enhances serological prevalence | 1.5 [1.4–1.7] | Rossel et al., 2006 | ||
| Using tylosine as growth promoter at the end of the fattening period | 1.6 [1.2–2.2] | Van der Wolf et al., 2001 | ||
| Using chlortetracycline as growth promotor during the fattening period | 6.9 [2.8–17.1] | Funk et al., 2007 | ||
| Serological prevalence is higher in pigs fed with a chlortetracycline, procaine penicillin and sulphamethazine supplemented ration versus approved growth promotor or probiotic | 4.1† [2.1–8.1] | Leontides et al., 2003 | ||
| Intercurrent diseases | Diarrhoea in growing pigs | NE | Møller et al., 1998 | |
| Infections by PRRSV (Porcine Reproductive and Respiratory Syndrome Virus) | 3.0 [1.3–6.7] | Beloeil et al., 2004a | ||
| Infections by PRCV (Porcine Respiratory Coronavirus) | 6.9 [2.2–21.6] | Fablet et al., 2003a; b | ||
| Infections by Lawsonia intracellularis | 2.1 [1.2–3.7] | Beloeil et al., 2004a | ||
| Liver infestations by Ascaris suum with high level (>16%) of liver condemnation at slaughterhouse during meat inspection | 2.1 [1.2–3.8] | Van der Wolf et al., 2001 | ||
NE, not possible to estimate.
*Calculated OR from published data.
†Epidemiological link showed by molecular strains typing methods.
‡Risk factor shown by modelisation.
§Results obtained from multiple factors analysis.