We are fighting a ubiquitous noxious pathogen
Salmonella is a rod-shaped Enterobacteriacea, ubiquitous and highly resistant in the environment, especially in water and with high environmental humidity. There are more than 2500 isolated serotypes, belonging to two species: Salmonella enterica and Salmonella bongori. The infective cycle is oro-fecal and pigs can be infected directly from other animals in the pen through the ingestion of contaminated feed and water. The infection is often asymptomatic, while the clinical form shows high temperature, lower feed intake, and diarrhea (catarrhal or hemorrhagic). Clinical signs are more common in growing animals and post-partum sows, but all age groups can be infected. Frequently, after clinical recovery, the pathology goes on in the subclinical form with Salmonella shedding becoming unnoticed. These reasons and the ability of this pathogen to translocate to the intestinal lining and invade other anatomic sites makes eradication very difficult with severe consequences both in animals and humans.
The zoonosis risk
Salmonellosis is the second most widespread food-borne zoonosis worldwide, normally characterized by abdominal pain, diarrhea, vomiting and, in most severe cases, septicemia and/or hospitalization. Human salmonellosis is often linked with animal products’ consumption and eating pork is among the most important causes. In the United States (US) the number of human cases of non-typhoidal salmonellosis has been estimated to be approximately 1.4 million, with approximately 15,000 hospitalizations and 580 deaths per year. Within the European Union (EU), there are more than 90,000 confirmed human cases of salmonellosis each year and Salmonella spp. is isolated from up to 29% of pigs at slaughter. Salmonella Typhimurium and Enteritidis are the two most important and controlled serotypes, but the vast majority of the isolates can be challenging for human health.
How can we limit infection and bacterial shedding?
In case of severe infection and clinical signs in pigs, antibiotics are needed. However, Salmonella increasing resistance to therapeutic antibiotics facilitates the subclinical form of infection and the subsequent continuous persistence in the environment. Therefore, the real challenge is to prevent the infection. Biosecurity is one of the most important points to look at: geographic location of the farm, animal density in the area, the type of farm (all in/all out, monospecies vs multispecies, etc..), the handling and the introduction/replacement of animals, as well as cleaning and disinfection at the end of the rearing cycle are all points of intervention when facing a Salmonella problem. Salmonella persists in the environment despite the high standards of biosecurity and segregation. However, other strategies like vaccination, diet formulation, and feed additives can help, though the spread of this pathogen and its diffusion must be tackled by multiple preventive and containment measures.
The Vetagro solution
is a slow-release premix based on the synergy between sorbic acid and nature identical compounds with strong in vitro and in vivo antimicrobial activity. In our study, conducted in partnership with the Istituto Zooprofilattico della Lombardia ed Emilia Romagna, reduced the fecal and intestinal prevalence of S. Typhimurium in a multisite pig farm from weaning to slaughter. The results indicate that the additive at 5 g/kg was able to reduce Salmonella fecal prevalence both in controlled and in production conditions.
References
- Food Standard Agency. (2007). Available at: https://assurance.redtractor.org.uk/contentfiles/Farmers-5504.pdf
- Sistema Informativo Sistema Veterinario – Regione Lombardia. (2005). Available at: http://www.vetinweb.it/cm_siv/sites/default/files/SUINI%20-%2005%20SALALMONELLOSI%20SUINI.pdf
- (2013). IZSTO. Available at: http://www.izsto.it/images/stories/allegati_eventi/zoppi.pdf
- WHO, 2018. Available at: https://www.who.int/en/news-room/fact-sheets/detail/salmonella-(non-typhoidal)
- Andres and Davies. (2015). Compr. Rev. Food. Sci. Food Saf. 14:317-335
- Voetsch, et al. (2004). Clin. Infect. Dis. 38(3):S127–S134
- Mead et al. (1999). Emerg. Infect. Dis. 5(5):607-625
- (2019). Available at: https://www.efsa.europa.eu/it/press/news/190218
- Wales and Davies. (2017). Zoonoses Public Health. 64(1):1-13
- White, et al. (2001). N. Engl. J. Med. 345(16):1147-1154
- Ministry of Agriculture, Foresty and Fisheries. Japan. Available at: http://www.maff.go.jp/j/syouan/kijun/wto-sps/oie/pdf/ref7_pig_salmonel_e.pdf
- Grilli et al. (2015a). Foodborne Pathog. Dis. 12(10):813-819