Suitability of a Salmonella control programme based on serology in slaughter heavy pigs

Gradassi, Matteo; Caminiti, Antonino; Galletti, Giorgio; Santi, Annalisa; Paternoster, Giulia; Tamba, Marco; Zanoni, Mariagrazia; Tagliabue, Silvia; Alborali, G. L.; Trevisani, Marcello

doi:10.1016/j.rvsc.2015.06.015

Cited by 7 publications

(8 citation statements)

References 36 publications

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“…The variability associated with the use of different ELISAs or matrices (serum or meat juice) has been also reported (Farzan et al., ; Mainar‐Jaime, Atashparvar, Chirino‐Trejo, & Blasco, ; Mejía, Casal, Mateu, & Martin, ; Vico & Mainar‐Jaime, ). Thus, the bias assumed when these ELISAs are used on individuals should be translated to the herd level as well, which probably make them unsuitable for proper herd risk characterization (Gradassi et al., ; Sørensen, Alban, Nielsen, & Dahl, ; Vico et al., ). The small sample size usually considered (between 36 and 100 pigs/year) for an infection whose presentation varies among batches and years, and the lack of representativeness of the on‐farm animal distribution, as pigs are usually sampled at slaughter, are factors that also may have contributed to increase that bias.…”

Section: Introductionmentioning

confidence: 99%

Looking for new approaches for the use of serology in the context of control programmes against pig salmonellosis

Jaime

Casanova-Higes

Andrés-Barranco

et al. 2017

Zoonoses and Public Health

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SummaryMost swine Salmonella national control programmes in Europe have been based on the categorization of herds according to risk levels based on serological results. However, none of the non-Scandinavian countries have reported of any significant success on Salmonella infection reduction in fattening pigs or the number of human cases attributable to pigs or pork. The limited accuracy of the tests used, the small number of animals sampled and the likely lack of herd representativeness of the samples used could be major factors affecting the suitability of these programmes. Focusing on minimizing Salmonella shedding at slaughter appears more important to prevent human infections than focusing on detection of seropositive pigs/herds at this stage. This study assessed whether performing on-farm serology may help to predict shedding at slaughter. Between 2010 and 2016, pigs from six cohorts from a Salmonella-positive herd were bled at 30, 60 and 90 days on fattening and before slaughter, and faecal samples collected at slaughter. Serology on days 60, 90 and before slaughter predicted somewhat shedding at slaughter with no significant differences among them. Pigs with higher OD% values at these point times would have higher risk of shedding when arriving to slaughter. The probability of shedding for a pig sampled on day 90 and showing an OD% value of 10 was 43%, and the risk increased up to 65% if the OD% was 40. Concluding, on-farm serology may help to determine to some extent the risk of Salmonella shedding at slaughter from seropositive fattening units, which would allow for prompt on-farm and slaughter interventions to reduce the likelihood of slaughter contamination with Salmonella.

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Section: Introductionmentioning

confidence: 99%

Looking for new approaches for the use of serology in the context of control programmes against pig salmonellosis

Jaime

Casanova-Higes

Andrés-Barranco

et al. 2017

Zoonoses and Public Health

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“…Seventeen MS submitted reports on Salmonella from pig meat, but the overall number of reports is significantly lower compared to the number of isolates obtained from pigs. This may be due to the fact that it is not compulsory to serotype isolates that are obtained from carcase swabs taken to fulfil the requirements of the EU Process Hygiene and Microbiological Criteria testing programmes (Gradassi et al, 2015).…”

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confidence: 99%

The European Union summary report on trends and sources of zoonoses, zoonotic agents and food‐borne outbreaks in 2014

2015

EFS2

231

118

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VTEC was reported from food and animals. A total of 5,251 food-borne outbreaks, including waterborne outbreaks, were reported. Most food-borne outbreaks were caused by viruses, followed by Salmonella, bacterial toxins and Campylobacter and with unknown causative agent in 29.1% of all outbreaks. Important food vehicles in strong-evidence food-borne outbreaks were 'eggs and egg products', followed by 'mixed food' and 'crustaceans, shellfish, molluscs and products thereof'. The report further summarises trends and sources along the food chain of tuberculosis due to Mycobacterium bovis, Brucella, Trichinella, Echinococcus, Toxoplasma, rabies, Coxiella burnetii

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“…Serologically positive pigs that are bacteriologically negative in MLN have been reported elsewhere (Kranker et al., ; Methner et al., ; Gradassi et al., ). Self‐cure has been suggested for some authors as a possible explanation for this situation (Kranker et al., ), while others simply assume that this health status is biologically possible because pigs can have an antibody response even when not infected (Gradassi et al., ). In this study, the majority of the pigs within this group showed very high OD% values (i.e.…”

Section: Discussionmentioning

confidence: 83%

“…The shedding of Salmonella in this group could be either the consequence of the exposure of non‐infected pigs to Salmonella‐ contaminated environments during transport or lairage, and the likely transient passage of the ingested salmonellae through the intestine (Gradassi et al., ), or a very recent Salmonella infection that has not reached the MLN. The invasion of gut‐associated lymph nodes (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…A large proportion (40%) of the sampled pigs within this group shed Salmonella while at farm, but in none of these pigs, Salmonella could be isolated from MLN, despite the fact that bacteriological analysis was performed twice on MLN samples to increase culture sensitivity. Serologically positive pigs that are bacteriologically negative in MLN have been reported elsewhere (Kranker et al, 2003;Methner et al, 2011;Gradassi et al, 2015). Self-cure has been suggested for some authors as a possible explanation for this situation (Kranker et al, 2003), while others simply assume that this health status is biologically possible because pigs can have an antibody response even when not infected (Gradassi et al, 2015).…”

Section: Odds Ratiomentioning

confidence: 99%

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Influence of On‐farm pig Salmonella status on Salmonella Shedding at Slaughter

Casanova-Higes

Andrés-Barranco

Jaime

2016

Zoonoses and Public Health

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The risk of Salmonella shedding among pigs at slaughter with regard to their previous on-farm Salmonella status was assessed in a group of pigs from a farm from NE of Spain. A total of 202 pigs that had been serologically monitored monthly during the fattening period and from which mesenteric lymph nodes (MLN) and faecal (SFEC) samples were collected at slaughter for Salmonella isolation were included. A repeated-measures anova was used to assess the relationship between mean OD% values during the fattening period and sampling time and bacteriology on MLN and SFEC. Pigs were also grouped into four groups, that is pigs seronegative during the fattening period and Salmonella negative in MLN (group A; n = 69); pigs seronegative during the fattening period but Salmonella positive in MLN (B; n = 36); pigs seropositive at least once and Salmonella positive in MLN (C; n = 50); and pigs seropositive at least once but Salmonella negative in (D; n = 47). Pigs shedding at slaughter seroconverted much earlier and showed much higher mean OD% values than non-shedders pigs. The proportion of Salmonella shedders in groups A and D was high and similar (26.1% and 29.8%, respectively), but significantly lower than that for groups B and C. The odds of shedding Salmonella for groups B and C were 4.8 (95% CI = 1.5-15.5) and 20.9 (3.7-118) times higher, respectively, when compared to A. It was concluded that a large proportion of Salmonella seronegative pigs may shed Salmonella at slaughter, which would be likely associated to previous exposure with contaminated environments (i.e. transport and lairage). For pigs already infected at farm, the likelihood of shedding Salmonella was much higher and may depend on whether the bacterium has colonized the MLN or not. The odds of shedding Salmonella spp. were always much higher for pigs in which Salmonella was isolated from MLN.

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Suitability of a Salmonella control programme based on serology in slaughter heavy pigs

Cited by 7 publications

References 36 publications

Looking for new approaches for the use of serology in the context of control programmes against pig salmonellosis

Looking for new approaches for the use of serology in the context of control programmes against pig salmonellosis

The European Union summary report on trends and sources of zoonoses, zoonotic agents and food‐borne outbreaks in 2014

Influence of On‐farm pig Salmonella status on Salmonella Shedding at Slaughter

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