1. FOOD-BORNE DISEASES Jutta Tebje-Kelly EpiCentre, Wool Building, Rm 2.04 116.407 Veterinary Public Health & Meat Hygiene

2. September 2005116.407 VPH & MH2 Introduction Causes of food-borne diseases/illnesses: 1.Chemical toxins (‘residues’) 2.Biotoxins – endotoxins & exotoxins 3.Infectious agents – exogenous & endogenous (‘zoonoses’)

3. September 2005116.407 VPH & MH3 Introduction contd endotoxins & exotoxins lipopolysaccharide (LPS) : protein part of bacterium : extracellular no toxoid : toxoid low potency : high potency low specificity : high specificity

4. September 2005116.407 VPH & MH4 Mode of action of some bacterial toxins S. aureus – A (alpha-toxin) E. coli – B (shiga toxin) C. botulinum – C (exo-enzyme)

5. September 2005116.407 VPH & MH5 Introduction contd Food hygiene vs food safety food hygiene – microbiological safety of food food safety – abscence of chemicals/residues Not necessary to have ‘sterile’ food

6. September 2005116.407 VPH & MH6 Prevention of food-borne diseases Organisms - characteristics 1.where from 2.types & strains 3.behaviour in food 4.survive or are killed by measures to inactivate

7. September 2005116.407 VPH & MH7 Prevention of food-borne diseases, contd Food – characteristics Water activity (a w ), pH and temperature

8. September 2005116.407 VPH & MH8 What influences occurrence of food-borne diseases/illnesses? Food source Food storage Food preparation Food handlers

9. September 2005116.407 VPH & MH9 What influences occurrence of food-borne diseases/illnesses? Time-temperature abuse Infected food handlers or inadequate hygiene during handling of food Consumption/use of unsafe food sources

10. September 2005116.407 VPH & MH10 Types of illnesses/diseases Upper GIT – nausea & vomiting Lower GIT – cramps & diarrhoea Neurological signs General symptoms

11. September 2005116.407 VPH & MH11 Types of illnesses/diseases Upper GIT signs Nausea, retching, vomiting, abdominal pain, diarrhoea & prostration S. aureus and its toxins B. cereus and its toxin

12. September 2005116.407 VPH & MH12 Types of illnesses/diseases Lower GIT signs Lower abdominal cramps & diarrhoea Clostridium perfringens, Bacillus cereus Salmonella, Shigella, ET E. coli, Yersinia enterocolitica, Campylobacter jejuni, Vibrio cholera

13. September 2005116.407 VPH & MH13 Types of illnesses/diseases Lower GIT signs, continued Lower abdominal cramps & diarrhoea Giardia intestinalis Cryptosporidium parvum

14. September 2005116.407 VPH & MH14 Types of illnesses/diseases Neurological signs Visual disturbances, vertigo, tingling sensation & paralysis Clostridium botulinum

15. September 2005116.407 VPH & MH15 Types of illnesses/diseases General symptoms Fever, chills, malaise, prostration, aches, swollen lymph nodes S. typhi, L. monocytogenes, C. jejuni Hepatitis A

16. September 2005116.407 VPH & MH16 Risks of contracting food- borne disease depend on: Host susceptibility Age General health

17. September 2005116.407 VPH & MH17 Infective dose Frequently exptrapolated Feeding studies (healthy, young adult volunteers) Estimates (data from outbreaks) ‘Worst case’ estimates

18. September 2005116.407 VPH & MH18 Risk assessment – variable infective doses Interaction – food substrate & environment pH susceptibility Type and strain

19. September 2005116.407 VPH & MH19 Control of food contamination Micro-organisms in food & water shellfish fruits & nuts beans watermelons spices & herbs vegetables

20. September 2005116.407 VPH & MH20 Control of food contamination Infection of animals – milk, eggs or meat Contaminated skins and guts - slaughter & dressing

21. September 2005116.407 VPH & MH21 Pathogenic Bacteria C. botulinum, C. perfringens - Soil, hide, faecal material Staphylococcus aureus toxin - Human (nostrils and hands) Listeria monocytogenes- Soil, hide, faecal material Campylobacter spp.- GIT (esp. poultry) E. coli O157:H7- GIT Salmonella spp.- GIT / Hide Yersinia enterocolitica- GIT

22. September 2005116.407 VPH & MH22 Control of food contamination Ideal = growing & harvesting stages But – ‘world is not sterile’ Prevent, reduce or limit by: Not allowing products from clinically ill animals to enter food chain Classical meat inspection - gross HACCP - microscopic

23. September 2005116.407 VPH & MH23 The chain of production from ‘farm to fork’ of food from animals Production Processing Final preparation and cooking Farm, Feedlot, Fishing site Slaughter Plant, Cannery, Packer, Food Factory Final Kitchen: commercial, institutional or domestic

24. September 2005116.407 VPH & MH24 The chain of production from farm to fork - prevention can occur at each step Production Processing Final preparation and cooking Feed, water, manure treatment, biosecurity, probiotics, vaccines HACCP, slaughter hygiene, pathogen reduction and elimination (pasteurization, irradiation) Cooking, preventing cross-contamination, worker education and hand washing

25. September 2005116.407 VPH & MH25 Prevention of Food Poisoning WHO ‘ten golden rules’ Food processed for safety Thoroughly cook Eat immediately Store carefully Reheat thoroughly

26. September 2005116.407 VPH & MH26 Prevention of Food Poisoning WHO ‘ten golden rules’ contd No contact between raw & cooked Wash hands Keep food preparation surfaces clean Protect from pests Use potable water

27. September 2005116.407 VPH & MH27 Food-borne disease outbreaks & food spoilage Contamination with undesirable micro-organisms Unacceptable levels of micro- organisms Treatment did not result in inactivation

28. September 2005116.407 VPH & MH28 Food-borne disease outbreaks & food spoilage Preventing/limiting contamination Preventing/limiting spread Preventing growth Preventing survival of organisms & persistence of metabolites

29. September 2005116.407 VPH & MH29 Microbiological/chemical hazards Micro-organisms – part of nature Chemicals – many are man-made Micro-organisms change numbers Uneven distribution in food Clinical symptoms – acute Variable consumer susceptibility