Monitoring of transmission of Salmonella enterica serovars in pigs using bacteriological and serological detection methods

Winsen, René L. van; Nes, A. van; Keuzenkamp, David; Urlings, H.A.P.; Lipman, L.J.A.; Biesterveld, Steef; Snijders, J. M. A.; Verheijden, J.H.M.; Knapen, F. van

doi:10.1016/s0378-1135(01)00313-3

Cited by 71 publications

(63 citation statements)

References 10 publications

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“…According to our results, Salmonella was isolated from the inoculated pigs in both trials early on the first day post-infection (Tables 1 and 2) which is in agreement with previous reports about rapid Salmonella shedding after experimental inoculation [7,26,27].…”

Section: Discussionsupporting

confidence: 92%

“…In the only available report about airborne transmission of S. Typhimurium in swine, no bacteria were isolated from sentinel animals exposed to airflow from a room with infected pigs and only seroconversion was observed [8]. Despite the large variation of time and frequency of Salmonella shedding that is seen in exposed pigs [26,27], S. Typhimurium can be rapidly isolated from faeces soon after they are commingled with animals shedding this pathogen [26], or when they are placed in a contaminated environment [16]. However, when infected and sentinel pigs had only nose-tonose contact, the majority of the exposed pigs shed S. Typhimurium after 5 weeks [8].…”

Section: Discussionmentioning

confidence: 99%

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Experimental airborne transmission ofSalmonellaAgona andSalmonellaTyphimurium in weaned pigs

2005

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SUMMARYThis study tested the hypothesis of airborne transmission of Salmonella Agona (Trial I) and Salmonella Typhimurium (Trial II) in weaned pigs. The trials were performed using stainlesssteel/glass isolation cabinets connected by air ducts to permit an unidirectional airflow from cabinet 1 (two control pigs) to cabinet 3 (two sentinel pigs), passing through cabinet 2 (two inoculated pigs). Air samples, pooled faecal samples from the floor and rectal swabs were collected daily and assessed by culture and PCR. A fumigation chamber and rubber gloves coupled to the cabinets allowed sampling without opening the system. Trials I and II lasted 15 and 19 days respectively. The recovery of S. Agona and S. Typhimurium and detection of seroconversion in sentinel pigs indicate that airborne Salmonella transmission in weaned pigs over short distances is possible. Further studies on the role of aerosols in the epidemiology of Salmonella in intensive pig production should be performed.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Experimental airborne transmission ofSalmonellaAgona andSalmonellaTyphimurium in weaned pigs

2005

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“…The probability of serologically detecting S. Typhimurium or S. Derby, was higher than for S. Goldcoast, S. Panama or S. Livingstone. Similar results were obtained in the study by Van Winsen et al [33] who concluded that some serovars may not be detected at all or may be detected to a lesser extent in different mix-ELISA currently used. Moreover, according to Nielsen et al [18], not all pigs do seroconvert.…”

Section: Discussionsupporting

confidence: 90%

“…being present in the intestines or the associated lymph nodes that is important with regards to contamination of the carcasses [5]. In many studies, the association between serological and bacteriological results as measured in faecal samples has been calculated at the herd level [9,11,16,25,28,33] and at the individual level 1 [10,28]. The authors agree that the serological test is suitable for screening on a herd basis in control programmes aiming to reduce Salmonella prevalence in pork.…”

Section: Introductionmentioning

confidence: 99%

Discrepancies between the isolation of Salmonella from mesenteric lymph nodes and the results of serological screening in slaughter pigs

et al. 2005

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-Most Salmonella control programmes are based on serological testing in the slaughterhouse. However, from a point of view of carcass contamination, it is rather the presence of Salmonella spp. in the animal at the time of slaughter that is important. The aim of this crosssectional study was to investigate the possible discrepancies between the isolation of Salmonella spp. in the mesenteric lymph nodes and the results of serological screening. In total, 1821 fattening pigs originating from 60 Belgian farrow-to-finish herds were sampled in the slaughterhouse. The serum samples were analysed using an indirect mix-ELISA for the presence of Salmonella antibodies and evaluated at 3 cut-off values namely 10, 20, and 40% Optical Density (OD). All mesenteric lymph node samples were submitted to qualitative Salmonella isolation and a representative number of isolates was serotyped. From each herd, 30 animals were screened both serologically and bacteriologically and the herd was considered as positive when at least one sample was positive. At the herd level, 83.6% (cut-off OD 40%) to 100.0% (cut-off OD 10%) of the herds from which Salmonella had been isolated were evaluated as seropositive. At the individual level, only 34.5% (cut-off OD 40%) to 82.8% (cut-off OD 10%) of the animals from which Salmonella had been isolated were seropositive. Overall, a weak agreement was found between bacteriology and serology for Salmonella diagnosis. If pig herds are categorised using serological tests in the slaughterhouse, one should be aware of the fact that slaughter pigs can still harbour Salmonella spp. in the mesenteric lymph nodes, without being detected in serological tests. The cut-off value used to evaluate a sample as serologically positive and the number of samples per herd are of major importance to classify herds correctly in order to protect human health.slaughter pig / Salmonella / bacteriology / serology * Corresponding author: nathalie.nollet@UGent.be Article published by EDP Sciences and available at

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“…Four mutually exclusive health states, measurable with available detection methods (bacteriology and serology [8,11]), are identified in the literature [22,33,34] and retained in this model ( Fig. 1): susceptible animals free of Salmonella (S), shedding animals (I − ), seropositive shedding animals (I + ), and seropositive carrying animals (C + ).…”

Section: Salmonella Infection States and Dynamicsmentioning

confidence: 99%

ModellingSalmonellaspread within a farrow-to-finish pig herd

et al. 2008

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-Delivery of infected pigs to the slaughterhouse is a major source of pork meat contamination by bacterial hazards to humans. We propose a model of Salmonella spread within a farrow-to-finish pig herd, assuming the prevalence in infected delivered pigs depends on the whole pig life-time and growing process. This stochastic discrete-time model represents both the population dynamics in a farrow-to-finish pig herd using batch management, and Salmonella spread. Four mutually exclusive individual health states were considered: Salmonella-free, seronegative shedder, seropositive shedder and seropositive not shedding carrier, making the distinction between seropositive animals and shedders. Since indirect transmission is the main route of transmission, the probability of infection depends on the quantity of Salmonella in the pigs' environment (Q). A dose effect function is used with two thresholds, assuming saturation in exposure for high Q vs. a minimum exposure for low Q. Salmonella is introduced in an initially Salmonella-free 150-sow herd. Prevalence of shedders and seroprevalence are calculated over time in batches of sows and pigs, and in groups of delivered pigs, composed of pigs from different batches. The model shows very variable seroprevalence over time within a herd among delivered groups, as well as among replications. The mean seroprevalence and the mean shedding prevalence are 19.3% and 13.8% respectively. A sensitivity analysis shows that the Salmonella quantity shed and the maternal protective factor are the most influential parameters on Salmonella prevalence in delivered pigs. swine / Salmonella / epidemiological model / population dynamics / environment

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Monitoring of transmission of Salmonella enterica serovars in pigs using bacteriological and serological detection methods

Cited by 71 publications

References 10 publications

Experimental airborne transmission ofSalmonellaAgona andSalmonellaTyphimurium in weaned pigs

Experimental airborne transmission ofSalmonellaAgona andSalmonellaTyphimurium in weaned pigs

Discrepancies between the isolation of Salmonella from mesenteric lymph nodes and the results of serological screening in slaughter pigs

ModellingSalmonellaspread within a farrow-to-finish pig herd

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