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Food hazard & non bacterial agents of foodborne illness

Food Microbiology

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Food hazard & non bacterial agents of foodborne illness

  1. 1. Presented by D. Mona Othman Albureikan Food Microbiology Food Hazard & Non-bacterial Agents of Foodborne Illness
  2. 2. Food Hazard - Food are complex mixtures of chemicals which contain compounds that potentially harmful as well as those that are beneficial. - A simple insufficiency will lead to so many diseases such as goiter (iodine deficiency), pellagra (nicotinic acid), beriberi (thiamine) and scurvy (ascorbic acid).
  3. 3. - Several vitamins are toxic if consumed in excessive amounts. -Green potatoes and potato sprouts contain the toxic alkaloid solanine which should be avoided. - Legumes or pulses contain a number of anti- nutritional factors such as phytate, trypsin inhibitors and lectins (haemagglutinins). - Many of these are destroyed by normal preparation producers such as soaking and cooking. Food Hazard
  4. 4. Possible causes of foodborne illness - Chemical-Intrinsic ( natural toxins). - Red kidney bean poisoning, (toxic mushrooms) -Extrinsic contamination. - Algae (paralytic shellfish poisoning). -Bacteria (infection and intoxication). - Fungi (mycotoxins). - Parasite, Protozoa,Viruses.
  5. 5. World Health Organization (WHO) -Foodborne disease has been defined by the World Health Organization (WHO) as: any disease of an infectious or toxic nature caused by food or water. -The WHO expert pointed out that foodborne disease ( microbial origin ) are the most widespread problem in the contemporary world and the cause of reduced economic productivity.
  6. 6. Risk Factors Associated With Foodborne illness Factors contributing to outbreaks of food poisoning: 1. Storage at ambient temperature. 2. Inappropriate cooling. 3. Contaminated processed food 4. Undercooking 5. Contaminated canned food 6. Inappropriate thawing 7. Cross contamination 8. Infected food handlers
  7. 7. The Site of Foodborne Illness. - The digestive tract: the pathogenic (disease producing) effect occur by giving rise to symptoms such as diarrhoea and vomiting. - In the mouth, food is mixed with saliva and broken down mechanically to increase the surface area available for attack by digestive enzyme.
  8. 8. -Saliva is an alkaline fluid containing starch-degrading (amylase) enzyme and the antimicrobial factors immunoglobulin (IgA), lyzozyme, lactoferrin and lactoperoxidase. -It provide assist chewing and swallowing and performs a cleansing function, rising the teeth and mouth to remove debris. The Site of Foodborne Illness
  9. 9. * In the stomach, food is blended with gastric juice, an acidic fluid containing hydrochloric acid that kill most of the micro-organisms but their spores survive. * In the small intestine most of the digestion and absorption of food occur. * In the healthy individual, the micro flora of the small intestine is mainly comprised of lactobacilli and streptococci, although , other bacteria have the ability to colonize the epithelium and cause illness as a consequence. The Site of Foodborne Illness
  10. 10. Non-bacterial Agents of Foodborne Illness - Helminths, nematodes, protozoa, viruses and toxic metabolites of fungi and algae.
  11. 11. Helminths & nematodes -There are number of animal parasites which can be transmitted to human via food and water. - These complex animals do not multiply in foods and they can not be detected and enumerated by cultural methods in the way that many bacteria can. - There presence is detected by direct microscopic examination often following some form of concentration and staining procedure.
  12. 12. Platyhelminths: liver flukes and tapeworms -The two most important classes of the Platyhelminths (flatworms) are the Trematoda, which includes the liver fluke Fasciola hepatica , and the cestoda which includes tapeworm s of the genus Taenia. - These organisms have complex life cycles which may includes quit unrelated hosts at different stages .
  13. 13. ROUND WORMS Perhaps the most notorious of the nematodes in the context of foodborne illness and the only one is trichinell spiralis , the agent of trichinellosis . This parasite has no free-living stage but is passed from host to host which can include a wide range of mammals including humans and pigs . Thus trichinellosis in the human population is usually acquired from the consumption of infected raw or poorly cooked pork products.
  14. 14. The control The presence of these parasite in animals usually gives rise to macroscopic changes in tissues and organs which can be recognized by meat inspection after slaughter.
  15. 15. Protozoa -Amongst the protozoa only a few genera are of special concern to the food microbiologist ; the flagellate Giardia, the amoeboid Entamoeba (histolytica) and three sporozoid genera Toxoplasma, Sarcocystis and cryptosporidium. found on salad vegetables and fruit and could occur on any foods which are washed with contaminated water or handled by persons not observing good hygienic practice.
  16. 16. TOXIGENIC ALGAE A number of planktonic algae can produce very toxic compounds which may be transported to filter-feeding shellfish such as mussels or small herbivorous fish which are food for larger carnivorous fish. These toxins pass to human by consumption which are most toxic. • PSP (paralytic shellfish poisoning) NSP (neurotoxic shellfish poisoning) . •* The toxins implicated in the various forms of shellfish poisoning are not only undetectable organoleptically but are also generally unaffected by cooking.
  17. 17. Dinoflagellate Toxins -The genus Alexandrium are the best known of a number of dinoflagellates responsible for paralytic shellfish poisoning. -The toxic metabolites of these algae, which includes saxitoxin and gonyautoxin block the nerve transmission causing symptoms such as tingling and numbness of the fingertips and lips, and respiratory paralysis.
  18. 18. Cyanobacterial toxins Several genera of freshwater cyanobacteria ,especially species of microcystis, anabaena reservoirs and may cause deaths of animals drinking the contaminated water.
  19. 19. Toxigenic fungi It is the ability of some moulds to produce toxic metabolites, known as mycotoxins, in foods and their association with a range of human diseases, from gastroenteric conditions to cancer. Mycotoxins of Aspergillus ( Aflatoxin is not only acutely toxic but, for the rat, it is amongst the most carcinogenicity compounds known). Maycotoxins of Penicillum ( Beriberi ) Mycotoxins of Fusarium ( Some species of fusarium cause economically disease of crop plants).
  20. 20. Three of the most important mycotoxins: -Aflatoxin. - Ochratoxin. - T-2 toxin. are immunosuppressive but react differently against the immuno system. Toxigenic fungi
  21. 21. Food borne viruses - As obligate intracellular parasites, viruses cannot Multiply other than in a susceptible host cell In recent years viruses have been recognized as an important cause of food borne illness.
  22. 22. Polio The only virus known to be food borne. Polio can be incubation period of 3-5 days and characterized by headache, fever and sore throat contaminated milk had been the principal source of foodborne polio but this route of infection had controlled by improvements in hygiene
  23. 23. Hepatitis A and E -Hepatitis A, the cause of infectious hepatitis. -The incubation period varies between two and six weeks. -During this period the virus multiplies in the cells of the gut epithelium before it is carried by the blood to the liver. -Hepatitis E virus, it has unusual (RNA) structure. - It is transmitted by the oral and produces illness after an incubation period of 40 days.
  24. 24. Gastroenteritis viruses -A number of different viruses have been implicated in gastroenteritis by their presence in large number in diarrhoeal stools. - Food borne viral gastroenteritis is characterized by an incubation period of 15-50h followed by diarrhoea and vomiting which persists for 24-48 h. - Enteric viruses may be introduced into foods either as primary contamination, at source where the food is produced, or as secondary contamination during handling, preparation and serving.
  25. 25. Control -An interesting approach is to use coli phage, a bacteriophage which infects the enteric bacterium e. coli, as a viral indicator. - Coliphages do not require expensive tissue culture techniques for their enumeration since they can be detected through their ability to from plaques in culture of a suitable strain of e. coli. - The problem of extraction of the coli phage from food remain .
  26. 26. Spongiform Encephalopathies -Spongiform encephalopathies are degenerative disorders of the brain that occur in a number of species. - They are recognized by the clinical appearance of the affected animal and the histological changes they produce in the brain. -Microscopic examination shows vacuoles in the neurons giving the grey matter the appearance of a section through a sponge
  27. 27. Scrapie -Scrapie,The disease of sheep and goats. -Its name is derived from one of the symptoms an itching which causes the infected animal to scrape itself against objects. • The agent of scrapie has been described as slow viruses Due to their long incubation periods. • It is now known as a prion.
  28. 28. Prion • It is contain no nucleic acid. • It is neither a bacterium nor a virus. • It is invisible in the electron microscope. • Cannot be cultured in media or cell cultures. and does not stimulate the formation of specific antibodies in infected animals.
  29. 29. References 1- James M. Jay. (2013). Modern Food Microbiology . Springer; Softcover reprint of the original 1st ed. 1996 edition (April 26, 2013) 2- Martin R. Adams and Maurice O. Moss. (2007). Food Microbiology. Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 0WF, UK. September 11, 2007. 3- Some pictures from different sits.