Review EU-wide baseline studies: achievements and difficulties faced Tine Hald * Microbiology and Risk Assessment, National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, 2860 Søborg, Denmark (e-mail: tiha@food.dtu.dk) With the purpose of providing the scientific basis for setting targets for Salmonella in food-producing animals, several EU-wide baseline studies to determine the prevalence of Sal- monella have been organised at the European Community level. The studies in laying hens and broilers are completed and reported. The achievements and difficulties faced are the main focus of this paper. The results support that poultry prod- ucts, and table eggs in particular, are important sources of human salmonellosis in EU. However, they also illustrate that with effective surveillance and control efforts, as imple- mented in several Member States, the prevalence, and thus the associated human infections, can be reduced significantly. Introduction Salmonella is an important cause of foodborne disease in humans throughout the world and is a significant cause of morbidity, mortality and economic loss (Adak, Long, & O’Brien, 2002; Mead et al., 1999; Roberts & Sockett 1994; Schroeder et al., 2005; Voetsch et al., 2004). Illness can range from a mild to severe gastroenteritis and in some people, invasive disease, which can be fatal. Long term sequelae such as reactive arthritis can also result from Salmonella infections. In 2006, the reported number of cases and incidence of human salmonellosis in the EU were 160,649 cases corre- sponding to 34.6 cases per 100,000 inhabitants (EFSA, 2007a). Salmonellosis continues to be the second ranking zoonosis in EU after campylobacteriosis, but the incidence has decreased over the past years, and in the last three years this decrease has been statistically significant. Of the more than 2500 serovars of Salmonella enterica, S.Enteritidis is the most frequently reported serovar causing more than 50% of the reported human Salmonella infections in the EU. The second most reported serovar is Salmonella Typhi- murium being reported from around 13% of the human cases. S. Enteritidis is also the serovar most often associated with eggborne infections in human, and eggs are consid- ered the predominant source of human salmonellosis in Europe as well as many other countries worldwide (Schroeder et al., 2005; Thorns, 2000). In the EU, eggs and egg products were the most frequently reported source of foodborne outbreaks caused by Salmonella in 2006 (EFSA, 2007a). The emergence of S. Enteritidis over the past 20e25 years in both table-egg laying hens and humans has been explained by the combination of two main factors: the extraordinary epidemiology of S. Enteritidis infections in laying hens and the centralised rearing of breeding stock (Thorns, 2000). In contrast to most other zoonotic Salmo- nella serovars, S. Enteritidis has been shown to be able to cause a lifelong colonisation of the peri-reproductive tissue of the laying hens (Humphrey, 1999). This may lead to col- onisation of the egg content during the formation of the egg in the reproductive tract. Due to this ability of vertical transmission, parent stock can transmit the infection to their progeny and laying hens can infect the content of eggs pro- duced for consumption. A few other serovars (e.g. S. Typhi- murium) may also be transmitted vertically although this occurs more seldom (EFSA, 2005). For Salmonella spp. in general, the usual route of infec- tion is through horizontal transmission. Infected or contam- inated animals will carry Salmonella in the faeces or on the skin, and for slaughter animals, the contamination or cross- contamination of carcasses is basically a question of redis- tributing the Salmonella bacteria from the positive animals during slaughter and further processing. The epidemiology of Salmonella at the slaughterhouse level is, therefore, primarily due to direct or indirect faecal contamination of live animals or carcasses (D’Aoust, 1989). The EU Zoonoses Regulation (EC) No 2160/2003 requires MSs to take effective measures to detect and con- trol Salmonella of public health significance in specified * Corresponding author. 0924-2244/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.tifs.2008.06.008 Trends in Food Science & Technology 19 (2008) S40eS48