Emerging food-borne zoonoses

Diarrhoeal diseases, almost all of which are caused by food-borne or waterborne microbial pathogens, are leading causes of illness and death in less developed countries, killing an estimated 1.9 million people annually at the global level. Even in developed countries, it is estimated that up to one third of the population are affected by microbiological food-borne diseases each year. The majority of the pathogens causing this significant disease burden are now considered to be zoonotic. The occurrence of some of these zoonotic pathogens seems to have increased significantly over recent years. The factors involved in such increases have not been well studied, but they are generally agreed to include changes in animal production systems and in the food production chain. Both types of changes can cause corresponding changes in patterns of exposure to the pathogens and the susceptibility pattern of the human population. This paper will not attempt a more in-depth analysis of such factors. The authors briefly describe five of the most important emerging food-borne zoonotic pathogens: Salmonella spp., Campylobacter spp., enterohaemorrhagic Escherichia coli, Toxoplasma gondii and Cryptosporidium parvum. The paper does not include a full description of all important emerging food-borne pathogens but instead provides a description of the present situation, as regards these globally more important pathogens. In addition, the authors describe each pathogen according to the new framework of a Food and Agriculture Organization (FAO)/World Health Organization (WHO) microbiological risk assessment, which consists of hazard identification and characterisation, exposure assessment and risk characterisation. Moreover, the authors provide a brief account of attempts at risk mitigation, as well as suggestions for risk management for some of these pathogens, based on thorough international FAO/WHO risk assessments. The authors emphasise the importance of science-based programmes for the continued reduction of pathogens at relevant points of the 'farm-to-fork' food production chain, as this is the only sustainable basis for further reducing risks to human health in the area of preventable food-borne diseases.