Salmonella Typhimurium environmental reduction in a farrow-to-finish pig herd using a live attenuated Salmonella Typhimurium vaccine

Abstract

Background Salmonella 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 presentation This 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. Conclusions This 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.

Nonspecific protection of heat-inactivated Mycobacterium bovis against Salmonella Choleraesuis infection in pigs

“…In these cases of low-efficient vaccines, training the innate immunity could be used to optimize the adaptive response to classical vaccines [ 4 , 5 ]. So, the use of HIMB as an immunostimulant combined with homologous vaccines against this pathogen could eventually improve serovar cross-protection [ 51 ].…”

Vaccine-enhanced competition permits rational bacterial strain replacement in the gut

“…Live-attenuated non-typhoidal Salmonella vaccines, carrying a mutation in aroA , which renders the strain auxotrophic for aromatic amino acids, are already used for broilers 30 and very similar auxotrophic strains are used in pig-farming 31 . In order to benchmark our approach to a known S .Tm vaccine we therefore compared protective efficacy and safety of the combined inactivated oral vaccine+ Ec 8178 treatment to that of S .Tm aroA vaccination.…”

“…Due to improved efficacy, the field of non-typhoidal Salmonella vaccine research has been strongly focused on live-attenuated vaccines. S .Tm vaccines are licensed only for the veterinary sector and both the poultry and swine vaccine are live, auxotrophic S .Tm strains 30,31 . These vaccine strains were originally tested in mice and showed protection against subsequent lethal infection with wildtype S .Tm 7 .…”

Evaluation of Non-Invasive Sampling Methods for Detection of Hepatitis E Virus Infected Pigs in Pens

“…BS samples were collected by treading through the faeces-covered floor and purposefully stepping into accumulated faecal material [ 21 ]. Afterwards, socks were collected individually in a plastic zipper bag [ 26 ].…”

“…Oral fluid samples can be used to detect HEV RNA or antibodies [ 18 , 19 , 20 ]. Boot socks are mainly used to detect Salmonella spp., in both poultry and pig farming [ 21 , 22 ] and have also been shown to be useful for HEV RNA detection [ 23 ]. For determination of the HEV status on the farm level, faecal dropping samples for HEV RNA detection have already proved to be accurate compared to serum sampling [ 24 ].…”