Longitudinal survey of the occurrence ofSalmonellain pigs and the environment of nucleus breeder and multiplier pig herds in England

Abstract

Epidemiological findings are reported from pig breeding units that were visited repeatedly and\ud sampled intensively for environmental Salmonella contamination. Eight pig breeding units\ud previously associated with Salmonella Typhimurium were visited during up to seven years. Samples\ud from voided faeces, surfaces, fomites and wildlife were cultured. Certain serovars were isolated\ud repeatedly on certain units, whilst others were detected only once or intermittently. A few serovars\ud were isolated consistently on some units but only intermittently on others. There was an association\ud between Salmonella in pens and in their immediate environment. S. Typhimurium was significantly\ud associated with growing pigs. Pens holding breeding stock for production herds were frequently\ud Salmonella-positive. Herds under common ownership showed similar serovar combinations.\ud Cleaning and disinfection was frequently ineffective. Wildlife serovars were typical of the associated\ud premises. On one unit, a low level of Salmonella was attributed to a small herd size, good cleaning\ud and disinfection and good rodent control. The study has shown that breeding herds are susceptible to\ud endemic infections with multiple Salmonella serovars and that cleaning, disinfection and vector\ud control may in many cases be inadequate. Finally, the prevalence of S. Typhimurium may be greater\ud in youngstock, which has important implications for public health

Quantifying Salmonella Population Dynamics in Water and Biofilms

“…Serovars like Newport and Give are often found in animal feces [43,44], and have been linked to several outbreaks of salmonellosis in the recent past (e.g., serovars Give [45,46], Thompson [47][48][49] and Newport [50]). Pathogenicity tests with C. elegans as host resulted in survival curves (Fig.…”

“…Isolates resembled the inoculated strains as demonstrated by identical rep-PCR patterns (data not shown). Cell numbers of strains inoculated into water at (5) 208 (44) 144 (27) 347 (58) 164 (12) 21 (4) 19 (4) nd not detected densities of about 10 6 cells ml −1 declined by up to 3 orders of magnitude to close to or below the detection limit of our qPCR protocol (i.e., 10 3 cells ml −1 ) within 2 days (Table 2). Strains were not detectable (nd, Table 2) or inconsistently detected with low numbers in replicate samples (0, Table 2) afterwards.…”

Evaluation of commonly-used farm disinfectants in wet and dry models ofSalmonellafarm contamination

“…Typically they employ yeast either as whole killed cells or an extract and/or serum albumin to simulate dirty conditions. The limitations of C&D in Salmonella-contaminated layer and pig units have been documented (Wales et al, 2006(Wales et al, , 2009Mannion et al, 2007), and in the authors' experience some disinfectants with proven performance in the standard tests do not appear to be as efficacious in field situations. There are many possible reasons for the failure of a disinfectant to perform as desired in a farm environment, and these include: unsuitable dilutions or coverage rates being used, inadequate prior cleaning (Ward et al, 2005(Ward et al, , 2006, and difficulties with access particularly in accommodation with complex equipment such as layer hen houses.…”

Evaluation of three intervention strategies to reduce the transmission of Salmonella Typhimurium in pigs

“…Although hygiene and biosecurity on-farm are of paramount importance in decreasing Salmonella seroprevalence in slaughterhouses (Hotes et al, 2011), Salmonella-free housing cannot be obtained simply by cleaning and disinfection regimens at farm level (Mannion et al, 2007;McLaren et al, 2011). Hence, such regimens should be combined with other measures as part of an overall strategy to control Salmonella on-farm (Wales et al, 2009).…”