IDENTIFICATION AND QUANTIFICATION OF RISK-FACTORS REGARDING SALMONELLA SPP ON PORK CARCASSES

The main elements of a descriptive epidemiological model for Salmonell a spp. in Dutch pig slaughterlines, and the subsequent quantification of risk factors regarding the contamination of carcasses, are describe d. There is a strong correlation between the number of live animals th at carry Salmonella spp. in their faeces and the number of contaminate d carcasses at the end of the slaughter-line. Live animals that carry Salmonella spp. are 3-4 times more likely to end up as a positive carc ass than Salmonella-free animals. Currently, about 50% of all carcass contamination results from the animals themselves being carriers, and 30% because other animals were carriers (i.e, cross contamination). Fu rthermore, it is estimated that in general between 5-30% of the carcas ses produced may contain Salmonella spp. With respect to carcass conta mination with Enterobacteriaceae and Salmonella spp., inadequately cle aned polishing machines (odds ratio, OR, 6) and 'inapt procedures duri ng evisceration' (OR 11), i.e, faulty evisceration and hygiene practic es, are the most important risk factors. An estimated 5-15% of all car cass contamination with Salmonella spp, occurs during polishing after singeing. The remainder is the result of current evisceration practice s (55-90%) and, to a lesser extent, further processing (5-35%), i.e dr essing, splitting and meat inspection. Less likely Salmonella spp. alr eady present on the skin of the live animals survive scalding and sing eing. However, because pigs are the only important source for the Salm onella contamination of the line and the carcasses produced, it can al so be concluded that if Salmonella-free pigs were produced, consumers could be provided with virtually Salmonella-free pork. As long as Salm onella-positive animals enter abattoirs, there will always be transmis sion of Salmonella spp. to consumers, even if the process is carried o ut according to stringent codes of good manufacturing practices (GMP). EU regulations should, therefore, allow for the decontamination of ca racasses with a safe substance, e.g. lactic acid, on the condition tha t the slaughterhouse strictly adhers to GMP principles. (C) 1997 Elsev ier Science B.V.