Current knowledge on foodborne bacterial zoonoses on farm

Since the 1990s, the occurrence of emerging foodborne bacterial zoonoses, represented by enterohemorrhagic Escherichia coli (EHEC) 0157 and Salmonella enterica infections, has been on the rise. Today public concern about the safety of animal products is mounting. Stock farms are composed of many elements, including animals, feedstuff, drinking water for animals, the breeding environment and managing staff. It is no easy task to totally eliminate microbiological hazards. But consumer demand for safe livestock products is Very strong and governments are working hard to establish a hygienic system at all stages from production to consumption, as well as to develop necessary technology. While it is important to develop measures for controlling carrier animals to eliminate the sources of foodborne pathogens, the fundamental step to be taken is to conduct proper hygienic management of livestock raising by taking account of the bacterial ecology on farms. EHEC 0157 is an emerging pathogen, first identified in 1982 as a causative agent of massive foodborne outbreak. Since then the cases of EHEC 0157 infection have been increasing mainly in industrial countries, raising a global issue. EHEC 0157 infection is often associated with the consumption of contaminated beef, raw milk, and other bovine products. There are also reports of direct infection of humans from cattle. Controlling EHEC infection as a foodborne zoonosis is a major public and animal health concern. In particular, cattle, and possibly swine, are important in the containment of EHEC 0157 within the farm environment. In order to reduce the risk of EHEC 0157 contamination on farms, it is essential to know the ecology of this organism in carrier animals and in the breeding environment, and then to define management factors which influence fecal shedding. Nontyphoidal Salmonellosis is one of the most commonly reported infections from all parts of the world. There are global pandemics of some serotypes of Salmonella enterica, such as Enteritidis phage type 4 and Typhimurium DT104. We have little knowledge as to the factors which have brought forth current pandemics. The recent emergence of the multidrug resistant S. Typhimurium DTI04 has reopened the debate on the agricultural use of antibacterial drugs and the use of alternative methods of control. A consequence of outbreak of these salmonellosis turned to be a public concern. In many countries regulatory laws have been enacted to control the prevalence and distribution of Salmonella infections among farm animals in order to preventfoodborne infection. Subclinical infections of farm livestock, however, may be associated with these organisms. As long as the organism is present on the farm, therefore, it is difficult to eliminate the infection, because transmission is sustained by environmental sources including manure and wild animals. We review the literature about the incidence of emerging foodborne diseases including EHEC 0157 and S. Typhimurium DT104 infections. We also discuss its ecology and preventive measures on the farm.