Abstract
BackgroundSalmonella Typhimurium is an important zoonotic pathogen in pigs, that can cause clinical disease. Many sow herds and finishing herds are infected with Salmonella, and therefore pose a threat for the contamination of pork and pork products and ultimately consumers.Case presentationThis case study describes a farrow-to-finish pig herd, producing its own replacement gilts, which had experienced clinical outbreaks of salmonellosis since 2002. Outbreaks were characterised by profuse diarrhoea, dead pigs and high antimicrobial use (colistin sulphate). The aim of this study was to see whether using vaccination of sows and piglets with Salmoporc®, a live attenuated Salmonella Typhimurium vaccine, in combination with standard hygienic precautions, it was possible to reduce Salmonella Typhimurium to below the bacteriological detection limit. Monitoring of the presence of Salmonella was done using a total of 20 pooled faecal, sock and dust samples per herd visit in the period from September 2016 to October 2020. Within the first 10 months after the start of vaccination in August 2016, there was a rapid reduction in clinical symptoms, antimicrobial usage and the number of Salmonella-positive samples. During the winters of 2017/2018 and 2018/2019 the number of positive samples increased again, however with minimal need to use antimicrobials to treat the affected animals. In July 2019, only two samples from a corridor were positive. In September and November 2019 and in October 2020 all three samplings were completely negative for S. Typhimurium.ConclusionsThis case, together with other longitudinal studies, can be seen as a proof of the principle that long term vaccination with a live attenuated S. Typhimurium vaccine can reduce the level of S. Typhimurium in the herd environment to very low levels within a farrow-to-finish herd initially suffering from clinical salmonellosis. Also, clinical symptoms indicating salmonellosis were no longer observed and antimicrobials to treat clinically diseased pigs were no longer needed.
Highlights
Salmonella Typhimurium is an important zoonotic pathogen in pigs, that can cause clinical disease
Typhimurium in the herd environment to very low levels within a farrow-to-finish herd initially suffering from clinical salmonellosis
Empty compartments are cleaned by high pressure cleaner with cold water and sanitised with a disinfectant containing glutaraldehyde/ quaternary ammonium components according to the Salmonella history of the farm A chronological history of the development of the Salmonella situation on the herd is given in Table 2 in the period from 2002 to August 2016 when vaccination was started
Summary
Salmonella Typhimurium is an important zoonotic pathogen in pigs, that can cause clinical disease. Within the first 10 months after the start of vaccination in August 2016, there was a rapid reduction in clinical symptoms, antimicrobial usage and the number of Salmonella-positive samples. Salmonella Typhimurium, and it’s monophasic variant, is a pathogen in the pig industry that can infect and colonize pigs [5]. This can lead to enteritis, both acute and subclinical, accompanied by a reduction in average daily weight gain and an increase in feed conversion ratio. Relevant control factors include all-in/all-out procedures, internal and external biosecurity, rodent-, fly- and beetle control, thorough cleaning and disinfection, improved pig management practices (e.g. reduction of cross fostering of suckling piglets and mixing of piglets at weaning or at transfer to the grow/finishing units), the use of specialized feed formulations, the use of organic acids and vaccination and the control of concomitant infections like Ascaris suum, PRRSV, ileitis or dysentery [10,11,12,13,14,15,16,17]
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