Prevalence and level of Listeria monocytogenes in ready-to-eat foods in Sweden 2010.

An increasing trend in human listeriosis cases over the past five years (2005-2009) in Sweden encouraged the authorities to examine the prevalence and levels of Listeria monocytogenes in ready-to-eat (RTE) foods in 2010. The combined results of two surveys are presented: the Swedish part of an EU-wide survey and a national survey. A total of 1590 samples covering three categories of RTE food able to support growth of L. monocytogenes: (i) soft and semi-soft cheeses (mould- and smear-ripened); (ii) heat-treated meat products; and (iii) smoked and gravad fish, were collected at retail outlets and analysed at the end of shelf life. L. monocytogenes was detected in 0.4% of 525 cheese samples, 1.2% of 507 meat-product samples and 12% of 558 fish samples. In the latter category, L. monocytogenes was found in 14% of both gravad and cold-smoked fish samples and in approximately 2% of hot-smoked fish samples. The percentage of cold-smoked or gravad fish testing positive for L. monocytogenes was significantly lower in samples processed in Sweden (8%) than in samples processed in other countries (45%). Levels of L. monocytogenes exceeding 100 cfu/g were found in one (0.2%) of the cheese samples and in three (0.5%) of the fish samples. The high prevalence of contaminated cold-smoked and gravad fish samples suggests that these products constitute the main problem. This has induced the development of a national strategy plan with the aim to halve the prevalence of L. monocytogenes in cold-smoked and gravad fish at retail in Sweden by the end of year 2015.