Medical brain notes 38

  Factors contributing to food safety concerns   Although it is difficult to determine the global incidence of food-borne disease, the World Health Organization (WHO) estimates that in 2005 alone, 1.8 million people died from diarrheal diseases, and in industrialized countries around 30% of the population is estimated to suffer from food-borne diseases each year (WHO, 2007). In the USA, for example, an estimated 76 million cases of food-borne diseases, resulting in 325 000 hospitalizations and 5000 deaths occur each year (Mead  et al. , 1999).   Changing food supply system   The increasing incidence of food-borne diseases is due to a number of factors, including changes in food production on the farm, new systems of food process-ing, longer distribution chains, and new food prepa-ration and storage methods. Changing lifestyles have led to a far greater reliance on convenience foods that are prepared outside the home, and which may have a longer preparation to co...

  Food-borne bacteria   The major cause of food-borne diseases is the con-sumption of microbiologically contaminated foods. There are many types of food-borne pathogens, including bacteria, viruses, and parasites. The charac-teristics of food-borne bacterial intoxications and infections are summarized in Tables 14.1 and 14.2, respectively. Food-borne pathogens are covered in more detail by Doyle  et al . (2001).  

  Food-borne viruses   It is only in recent years that the role of viruses as etiological agents of food-borne illness have emerged. Difficulties in attributing viral illness to food have mainly been due to the diagnostic difficulties in detecting viruses in an implicated food and under-reporting owing to the mild nature of illness in many cases. A report from the US Centers for Disease Control (CDC) in 2000, on surveillance of food-borne disease outbreaks from 1993 to 1997, revealed that viruses accounted for 6% of all food-borne out-breaks and 8% of cases. Hepatitis A accounted for the majority of these, followed by norovirus. Data pub-lished by the European Food Safety Authority (EFSA) revealed that viruses accounted for 10.2% of all food-borne outbreaks reported during 2006. Caliciviruses (including norovirus) accounted for the majority (61.7%) of these food-borne viral outbreaks. Food-borne viruses are generally enteric, being transmitted by the fecal–oral route. However,...

  Food-borne parasites   Food-borne parasitic diseases are a major public health problem affecting millions of people, predomi-nantly in nonindustrialized countries. The incidence of parasitic disease associated with the consumption of foods of animal origin has declined in industrial-ized countries in recent years, where improvements in animal husbandry and meat inspection have led to considerable safety and quality gains. The situation in nonindustrialized countries is very different, in that these diseases are associated with poor standards of sanitation and hygiene, low educational standards, and extreme poverty.   Parasites are organisms that live off other living organisms, known as hosts. They may be transmitted from animals to humans, from humans to humans, or from humans to animals. Food-borne parasitic disease occurs when the infective stages of parasites are eaten in raw or partially cooked protein foods, or in raw vegetables and fruits that are inadequately wa...

  Transmissible spongiform encephalopathies and food   Transmissible spongiform encephalopathies (TSEs) are fatal degenerative brain diseases which include BSE in cattle; scrapie in sheep; kuru, Creutzfeldt– Jakob disease (CJD), and new variant CJD (vCJD) in humans. They are characterized by the appearance in the brain of vacuoles – clear holes that give the brain a sponge-like appearance – from which the condi-tions derive their name.   Several theories have been proposed to explain the nature of the agents that cause TSE. Prusiner was awarded the Nobel Prize in 1997 for the prion theory, which postulates that the agent is a proteinaceous infectious particle (PrP) that is capable of replication without the need of an agent-specific nucleic acid. The disease-associated prion (PrP Sc ) has been shown to have a different helical shape to normal cellular prion protein (PrP C ) found on neuronal cells and some other cells, for example lymphoid cells. However, while it is wide...

  Chemicals affecting food safety   Chemicals may be present in food owing to their natural occurrence in soil (e.g., cadmium, lead) or from fungal contamination (e.g., aflatoxins, ochra-toxin), from algal contamination [e.g., amnesic shell-fish poisoning (ASP), diarrhetic shellfish poisoning (DSP), azaspiracid shellfish poisoning (AZP), para-lytic shellfish poisoning (PSP)], from industrial or other pollution [e.g., lead, mercury, polychlorinated biphenyls (PCBs), dioxins], from agricultural and vet-erinary practices (e.g., pesticides, fertilizers, veteri-nary drugs) or from food processing and packaging techniques [e.g. acrylamide, polycyclic aromatic hydrocarbons (PAHs), 3-monochloropropane-1,2-diol (3-MCPD), bisphenol A diglycidyl ether (BADGE)]. Toxicological assessment of these substances is largely carried out on an international basis by expert groups such as the Joint Expert Committee on  Food Additives and Contaminants (JECFA) or Joint Meeting on Pesticide Resid...