Salmonella in pigs, pork and people

According to the Center for Disease Control and Prevention, in the US, salmonellosis is the costliest foodborne illness in people. Its annual cost to our southern neighbours is estimated at over 4 billion US dollars. Pork is the third most frequent source of contamination for humans, behind chicken and fruits.

The monophasic Salmonella, which is a variant of Salmonella Typhimurium and is designated as serovar I 4,[5],12:i:-, is now the most frequent multidrug resistant serovar that affects humans in the US.¹ Among outbreaks related to that multidrug resistant serovar, 63% were associated with pork consumption or contact with pigs.²

In Canada, year after year salmonellosis continues to be, by far, the most frequent enteric illness in people of our country. Data from 2019 show that Salmonella was involved in 6350 cases, way in front of enteric viruses, with 2656 cases.³ Serovars Typhimurium and monophasic I 4,[5],12:i:- were second and third in importance, behind Enteritidis, which mainly involves poultry products.

In swine production, monophasic I 4,[5],12:i:- is the serovar most frequently identified. In 2021, 58% of the swine cases in Quebec were associated with it, more than all other serovars combined. Together with Typhimurium, they represented 79% of all cases (30/38) in diagnostic laboratories.⁴

Controlling Salmonella, in particular the monophasic and Typhimurium serovars, can thus be beneficial on both the human and swine sides. Plumb et al² reported that preventing carriage of the monophasic Salmonella in swine would likely avert human infections with this strain.

Enterisol Salmonella T/C^® is the only vaccine that has been shown to reduce losses associated with infection with both the monophasic and Typhimurium strains in pigs. Furthermore, it was also shown to reduce the carriage of these strains after infection.^5,6 In a recent experiment, pigs infected with the monophasic strain were less likely to remain carrier after infection, and the quantity of Salmonella found in those that remained infected was more than 10 times lower than for unvaccinated pigs.⁶

Enterisol Salmonella T/C^® is one of the tools that can be used to control salmonellosis. Another tool that has been shown to reduce the risk associated with Salmonella is Enterisol^™ Ileitis. When challenged with both Lawsonia intracellularis and Salmonella Typhimurium, pigs previously vaccinated with Enterisol^™ Ileitis showed decreased shedding of Salmonella after infection.⁷

The control of Salmonella in pigs can have a positive impact on their health, on the microbial quality of their meat and, ultimately, on the health of people.

References

1. Trachsel JM, Bearson BL, Brunelle BW, Bearson SMD. Relationship and distribution of Salmonella enterica serovar I 4,[5],12:i:- strain sequences in the NCBI Pathogen Detection database. BMC Genomics. 2022 Apr 6;23(1):268. doi: 10.1186/s12864-022-08458-z.
2. Plumb ID, Brown AC, Stokes EK, Chen JC, Carleton H, Tolar B, Sundararaman P, Saupe A, Payne DC, Shah HJ, Folster JP, Friedman CR. Increased Multidrug-Resistant Salmonella enterica I Serotype 4,[5],12:i:- Infections Associated with Pork, United States, 2009–2018. Emerg Infect Dis. 2023;29(2):314-322.
3. Public Health Agency of Canada. National Enteric Surveillance Program (NESP), Annual summary 2019; December 2020.
4. RAIZO (Réseau d’Alerte et d’Information Zoosanitaire du Québec), 2021 data.
5. Neubauer A, Roof MB. Evaluation of the Enterisol Salmonella T/C^® vaccine strains against challenge with a virulent Salmonella serovar Typhimurium isolate. Proc AASV, annual meeting, 2015;171-174.
6. Leite F, Arruda P, Jordan D, Bearson S. Evaluation of the effect of an oral vaccine on the shedding and lymph node colonization of multidrug resistant monophasic Salmonella enterica serovar I 4,[5],12:i:-. AD Leman Swine Conference, 2022, Research Abstracts; poster 41.
7. Leite FLL, Singer RS, Ward T, Gebhart CJ, Isaacson RE. Vaccination Against Lawsonia intracellularis Decreases Shedding of Salmonella enterica serovar Typhimurium in Co-Infected Pigs and Alters the Gut Microbiome. Scientif Rep. 2018;8:2857| DOI:10.1038/s41598-018-21255-7.

Enterisol Samonella T/C^® is a registered trademark of Boehringer Ingelheim Vetmedica GmbH, used under license.
Enterisol^® is a registered trademark of Boehringer Ingelheim Vetmedica GmbH, used under license.
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