Prevalence and serovars of Salmonella enterica on pig carcasses, slaughtered pigs and the environment of four Spanish slaughterhouses Héctor Arguello ⁎, Ana Carvajal, Jesús A. Collazos, Carina García-Feliz, Pedro Rubio Infectious Diseases and Epidemiology Unit, Department of Animal Health, Faculty of Veterinary Science, University of León, León, Spain abstract article info Article history: Received 15 February 2011 Accepted 13 April 2011 Keywords: Salmonella Slaughterhouse Pig carcass Contamination source Serotyping The purpose of this study was to investigate the prevalence of Salmonella contamination and main serovars in pig slaughterhouses in Spain including carcasses, live animals and the environment. A total of 896 pig carcasses were randomly selected and swabbed before chilling in 3–5 visits to four pig slaughterhouses (A, B, C and D). Salmonella contamination was detected in 39.7% of the carcasses. The prevalence of positive carcasses was similar amongst slaughterhouses but significant differences were observed when taking sampling day into consideration within each of the slaughterhouses. Furthermore, a significant reduction in the prevalence of Salmonella contaminated carcasses (10.8%) was demonstrated in slaughterhouses C and D after chilling and cooling procedures. Sixteen batches of 10 animals were tracked from farm-to-slaughterhouse in slaughterhouses A and B to investigate the relationship between carcass contamination and contamination in live animals entering the slaughterhouse. No difference was found between infected and uninfected animals with respect to Salmonella contamination of the carcass although an increase in Salmonella contamination during the processing of live pigs into pork carcasses was evident. Regarding contamination in the slaughterhouse environment, Salmonella was isolated from most of the evaluated points in the slaughter line of the four studied slaughterhouses. Holding pens were identified as highly contaminated and what is more the ineffectiveness of the routinely cleaning protocols at this level was demonstrated in slaughterhouses C and D. The predominant Salmonella serovars found in carcasses, live pigs entering the slaughterhouse and the environment of the slaughterhouse were S. Typhimurium, S. Rissen, S. Derby and S. 4,[5],12:i:-. The same serovars were found in all the stages supporting the hypothesis that infected pigs are the main source of Salmonella contamination within slaughterhouses. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Salmonella is the most common cause of food-borne outbreaks and the second most reported zoonotic disease in the EU (EFSA, 2010a). Although eggs (or products thereof) and poultry meat are the biggest contributors to these outbreaks, pig meat has also been recognised as an important source of human salmonellosis since the early 90s (Baggesen & Wegener, 1994; Mousing et al., 1997; Wegener, Baggesen, & Gaarslev, 1994). Due to this, many European countries have already implemented Salmonella control programmes for pigs and pork (Nielsen & Wegener, 1997; Rowe et al., 2003; Small et al., 2006). Such programmes should ensure that proper and effective measures to detect and control Salmonella are taken at all relevant stages of production, processing and distribution, particularly at the level of primary production, and they will soon be compulsory in the EU (Regulation EC no, 2160/2003). Pigs are susceptible to a wide variety of serovars of Salmonella, and infected pigs usually remain healthy carriers. These sub-clinically infected pigs may excrete Salmonella spp. in their faeces or keep the bacteria in their digestive tract, the closely associated lymph nodes or the tonsils (Fedorka-Cray et al., 1999). Salmonella-carrier pigs are not identified during ante and post-mortem veterinary inspections, and they theoretically will not contain the bacteria on their carcass if the slaughtering process is carried out properly. However, it has been reported that these animals are the major contamination source for the slaughterhouse and the processing environment (Berends, Van Knapen, Snijders, & Mossel, 1997). Handling and hygiene practices are essential to prevent cross contamination during the slaughtering process, and several interventions at this level have been proposed in order to reduce the hazard to consumers (Alban & Stärk, 2005; Baptista, Halasa, Alban, & Nielsen, 2010; Goldbach & Alban, 2006; Lawson, Jensen, Christiansen, & Lund, 2009). Spain is currently the second largest pig producer in the EU and pig meat exports have reached 1.25 t in 2008 (data from the Spanish Ministry of Agriculture and Livestock). Previous studies have reported a high prevalence of Salmonella infection in Spanish pigs (EFSA, 2008b, Food Research International 45 (2012) 905–912 ⁎ Corresponding author at: Facultad de Veterinaria (Enfermedades Infecciosas), Campus de Vegazana, 24071 León, Spain. Tel.: + 34 987 291306; fax: + 34 987 291304. E-mail address: hector.arguello@unileon.es (H. Arguello). 0963-9969/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2011.04.017 Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres