Weaned piglets: another factor to be considered for the control of Salmonella infection in breeding pig farms

Abstract

Field studies on Salmonella infection in suckling piglets are scarce due to the intrinsic difficulties of collecting proper samples (i.e. tonsils or mesenteric lymph nodes), and most of them rely on the analysis of rectal swabs that limit their accuracy. We used 495 slaughtered 4-weeks-old male piglets intended for human consumption from 5 Salmonella -seropositive breeding farms to collect gastrointestinal packages and perform a thorough detection of Salmonella on mesenteric lymph nodes and intestinal content. The overall prevalence of both infection and shedding was high (≈ 36%) indicating that piglets played an active role in Salmonella maintenance in the farms. Major serotypes found in piglets included 4,[5],12:i: (35.4%), Rissen (17.1%), Derby (10.9%) and Bovismorbificans (10.3%). In most of the infected animals (72.8%) the same serotype was found in mesenteric lymph nodes and feces. Significant higher ELISA OD% values were found in meat juice samples from non-infected piglets compared to infected ones (median OD% of 12.0 and 17.3, respectively; P = 0.002) suggesting some protective effect of sow’s colostrum. Salmonella was also isolated from feces from weaned sows contemporary of the slaughtered piglets, and 89% of the serotypes identified in sows were also detected in piglets. Pulsed field gel electrophoresis analyses showed that 75% of the piglet isolates that were compared to those of sows were related to them, suggesting the circulation of Salmonella strains between sows and piglets. It appears that improving piglet colostrum intake along with the reduction of the shedding in sows may favor the control of Salmonella infection in breeding farms.

Spatial Trends in Salmonella Infection in Pigs in Spain

“…Still, due to the absence of a national control/monitoring program for Salmonella in pigs in Spain, little is known about the spatial distribution of Salmonella infection in pigs in Spain. The only available data came from specific studies with a generally limited geographical and temporal scope (10)(11)(12). The Spanish Veterinary Antimicrobial Resistance Surveillance Network program (13), starting in 1997, has performed nationwide surveillance of antimicrobial resistance originating from foodborne bacteria, such as Escherichia coli, Campylobacter spp., and Salmonella spp.…”

Salmonella Infection in Mesenteric Lymph Nodes of Breeding Sows

“…Salmonella can be present in feces after an active infection of enterocytes and lymphatic system and/or by passive transmission of the bacteria through the gut after ingestion. Sows infected asymptomatically can shed the pathogen intermittently contaminating the environment (Scherer et al, 2008) and transmitting it to humans and piglets (Casanova-Higes et al, 2019). Reliable diagnostics of Salmonella infection can only be assessed by the pathogen isolation in the gut wall or lymphatic system, being mesenteric lymph nodes (MLNs) the sample of choice (DOUE, 2003;EFSA, 2006).…”

Examining the Effect of Host Recruitment Rates on the Transmission of Streptococcus suis in Nursery Swine Populations

“…Mechanical vectors including mice and houseflies have also been implicated as vehicles of S. suis transmission; while feces, contaminated feed, water, work boots, and needles have also been shown to transmit the bacterium [1,42]. Breeding rooms may also serve as a potential source of transmission, similar to Salmonella infections in pigs [43]. While such introductions can occur, S. suis is endemic on most swine farms worldwide and the detection of S. suis on farms is likely not a good predictor for strains of clinical relevance.…”