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Salmonella infection


Only two species of the genus Salmonella exist: Salmonella enterica and Salmonella bongori. Salmonella enterica contains six subspecies, of which Salmonella entrica subsp. enterica represents the largest group with more than 1500 serotypes, including e.g. Salmonella Enteritidis and Salmonella Typhimurium.


Names of serotypes of Salmonella are assigned to determined formulas which are obtained after agglutination of a culture of Salmonella with specific antisera. The sera are directed against the somatic antigens (O Ag, lipopolysaccharides) or against the flagellar antigens (H Ag, proteins). The combination of O and H antigens corresponds to an antigenic formula that is transcribed in a serotype name (for example the profile O4: i:2 corresponds to Salmonella Typhimurium).

The full list of serotypes is described in the Kauffmann-White scheme that can be found on:

SalmonellosisSalmonella are essentially intestinal bacteria but can be found in the environment, feedstuffs, food producing and other animals, including cool blooded animals, foods, humans and their sewage. Salmonella infections in humans mainly cause diarrhoea, nausea, vomiting and fever.
In young children, in elderly and in immunocompromised people septicaemia may occur which may in rare cases lead to death.


On the other hand, Salmonella infection in humans and in animals may remain without any clinical sign but in spite of that the host may excrete Salmonella. Such carrier animals in poultry or pigs represent a risk for spreading the infection to other flocks and herds and for public health since eggs, poultry meat and pork may be contaminated with Salmonella and thus enter the food chain.


For this reason, official control programmes in poultry and pigs are set up in all European countries.


Besides zoonotic Salmonella, host-specific Salmonella also exist. In Belgium poultry is checked for Salmonella Gallinarum, which does not represent a risk to human health but induces pullorum disease in young chickens, and fowl typhoid in elder animals.


Diagnosis of Salmonella contamination of the environment or feedingstuffs and Salmonella infection in animals is based on the bacteriological identification of the bacterium in appropriate material (swabs, faeces, organs, ...).


Internationally accepted methods (norm ISO6579) are used in official control programmes. These consist of a pre-enrichment to stimulate the growth of injured Salmonella, an enrichment in specific media that suppress overgrowth of contaminating bacterial flora, and plating on agar media to recognize presumptive colonies. Salmonellosis


Final identification is done by biochemical tests and agglutination with specific antisera. Care should be taken to choose the appropriate enrichment medium since media with low concentration of agar only allow the swarming of mobile Salmonella, and therefore does not permit the detection of Salmonella that do not express flagellae e.g. Salmonella Gallinarum.


ELISA tests are routinely used in finishing pigs to estimate the infection status of the herd. Since no vaccine for pigs is registered in Belgium, this test is rather reliable. The test is based on the detection of specific O antigens and therefore is serotype dependent.

As for S. Gallinarum in poultry, serum agglutination is a test that can be done in the beginning of the production round.


Notifiable Disease :

Official control programmes exist for Salmonella infections in poultry (breeders, layers and broilers) and in finishing pigs.

In addition, each Salmonella in the primary production may present a risk for public health, and should be notified to the Federal Agency for the Safety of the Food Chain (FASFC).



As National Reference Laboratory for Salmonella, animal health (primary production), all strains from official surveillance and monitoring programmes are serotyped at CODA-CERVA. Beside the classical serotyping according to Kauffmann-White, recently a commercial, genetic typing method (Premi®Test Salmonella) is being evaluated and is used in case of non-typable strains or doubtful results.


A selection of Salmonella isolates sent to CODA-CERVA for serotyping is routinely tested for their resistance against antimicrobial agents. Based on the serotyping and sensitivity testing each year a report is published.


The laboratory is part of the CRL for Salmonella network in Bilthoven, The Netherlands.


The Belgian Reference Centre for Salmonellosis in human is the Scientific Institute of Public Health (ISP-WIV).

Current research aims at the further evaluation of the Premi®Test Salmonella for non-typable Salmonella strains. Whereas detection of somatic and flagellar antigens is depending on expression of antigens for classic serotyping, this is not the case for the genetic Premi®Test Salmonella.
In addition, in the beginning of 2010, research started on Salmonella in pigs. At CODA-CERVA an evaluation will be done of the diagnostic tests (serology and bacteriology), the sampling at the slaughterhouse and the cost-effectiveness of the current measures at the pig farm.
Scientists involved in routine diagnosis and research participate in numerous official working groups organised by the Federal Public Service, Health, Food Chain Safety and Environment, and the Federal Agency for the Safety of the Food Chain.


Vicky Jasson : Serotyping, ELISA Salmonella in pigs
Pierre Wattiau : Premi®Test Salmonella, S. Gallinarum


Please find here the Salmonella Report 2010 of CODA-CERVA

2014 : Note sur les variants monophasiques de Salmonella


C. Boland, S. Bertrand, W. Mattheus , K. Dierick and P. Wattiau. Molecular Typing of Monophasic Salmonella 4,[5]:i:- Strains Isolated in Belgium (2008-2011). Vet Microbiol 168 (2014) 447-450


- Bertrand S, Dierick K, Heylen K, De Baere T, Pochet B, Robesyn E, Lokietek S, Van Meervenne E, Imberechts H, De Zutter L, Collard JM. Lessons learned from the management of a national outbreak of Salmonella ohio linked to pork meat processing and distribution. J Food Prot. 2010 Mar;73(3):529-34.

- Bollaerts K, Messens W, Aerts M, Dewulf J, Maes D, Grijspeerdt K, Van der Stede Y. Evaluation of scenarios for reducing human salmonellosis through household consumption of fresh minced pork meat. Risk Anal. 2010 May;30(5):853-65.


- Huehn S, Helmuth R, Bunge C, Guerra B, Junker E, Davies RH, Wattiau P, van Pelt W, Malorny B. Characterization of pathogenic and resistant genome repertoire reveals two clonal lines in Salmonella enterica subsp. enterica serovar Paratyphi B (+)-tartrate positive. Foodborne Pathog Dis. 2009,6(4):431-43.

- Namata H, Welby S, Aerts M, Faes C, Abrahantes JC, Imberechts H, Vermeersch K, Hooyberghs J, Méroc E, Mintiens K. Identification of risk factors for the prevalence and persistence of Salmonella in Belgian broiler chicken flocks. Prev Vet Med. 2009,90(3-4):211-22
- Bollaerts KE, Messens W, Delhalle L, Aerts M, Van der Stede Y, Dewulf J, Quoilin S, Maes D, Mintiens K, Grijspeerdt K. Development of a quantitative microbial risk assessment for human salmonellosis through household consumption of fresh minced pork meat in Belgium. Risk Anal. 2009 ,29(6):820-40.

- Boone I;, Van der Stede Y., Bollaerts K., Vose D., Maes D., dewulf J., Messens W., Daube G., Aerts M., Mintiens K. NUSAP Method for Evaluating the Data Quality in a Quantitative Microbial Risk Assessment Model for Salmonella in the Pork Production Chain. Risk Anal. 2009, 2009, 29(4):502-17.

- Boone I., Van der Stede Y., Bollaerts K., Messens W., Vose D., Daube G., Aerts M., Mintiens K. Expert judgement in a risk assessment model for Salmonella spp. in pork: The performance of different weighting schemes. Prev vet med, 2009,92(3),224-34

- Cortiñas Abrahantes J., Bollaerts K., Aerts M., Ogunsanya V., Van der Stede Y. Salmonella serosurveillance: Different statistical methods to categorise pig herds based on serological data. Prev Vet Med. 2009, 2009,89(1-2):59-66.

- Delhalle L, Saegerman C, Messens W, Farnir F, Korsak N, Van der Stede Y, Daube G. Assessing interventions by quantitative risk assessment tools to reduce the risk of human salmonellosis from fresh minced pork meat in Belgium.

- J Food Prot. 2009 Nov;72(11):2252-63. Boone I, Van der Stede Y, Bollaerts K, Messens W, Vose D, Daube G, Aerts M, Mintiens K. Expert judgement in a risk assessment model for Salmonella spp. in pork: the performance of different weighting schemes. Prev Vet Med. 2009 Nov 15;92(3):224-34.

- Delhalle L, Saegerman C, Messens W, Farnir F, Korsak N, Van der Stede Y, Daube G. Assessing interventions by quantitative risk assessment tools to reduce the risk of human salmonellosis from fresh minced pork meat in Belgium. J Food Prot. 2009 Nov;72(11):2252-63.


- Wattiau P, Van Hessche M, Schlicker C, Vander Veken H, Imberechts H. Comparison of classical serotyping and PremiTest assay for routine identification of common Salmonella enterica serovars. J Clin Microbiol. 2008 Dec;46(12):4037-40
- Wattiau P., Weijers T., Andreoli P., Schlicker C., Vander Veken H., Maas H., Verbruggen A., Heck M., Wannet W., Imberechts H., Vos P. Evaluation of the Premi®Test Salmonella, a low-density DNA microarray system intended for routine identification and typing of Salmonella enterica. Int j food microbial, 2008,123(3), 293-98