contaminants

• Food contamination


  Food contamination due to environmental contamination
• Transport of raw materials


  1. Food conditioning - storage of raw materials, preheating, disinfection, cleaning, and sterilization steps

  2. Heating

  3. Food packaging

  4. Transport, storage, and food distribution
• Food-Borne biological hazards


  • Cestodes (tapeworms)
  • Nematodes
  • Trematodes (flatworms or flukes)
  • Protozoa
• Cestodes


  • Taenia solium
  • T. saginata
• Nematodes


  • Some nematodes, such as Ascaris, have a simple life cycle with no intermediate host and are passed from one human to another
  • Trichinella, Anisakis, exist as cysts in muscles of meat or fish
• Toxoplasma gondii


  Toxoplasmosis, intracellular protozoan, pregnant women/immunocompromised at greatest risk, signs include fever, headache, swollen lymph nodes, severe toxoplasmosis can damage eye/brain, one of the three leading causes of death from a foodborne disease
• How can parasites be controlled?


  1. Sanitation and Hygiene - Proper disposal of human and animal wastes, control of flies, cockroaches, and other insects, thorough washing, frequent handwashing

  2. Animal Husbandry - Rodent control, infected animals may be treated with drugs to kill parasites, and vaccines are being developed

  3. Inspection systems

  4. Processing - Irradiation can destroy parasites, lower doses of irradiation (0.5–0.7 kGy) damage larvae and inhibit infectivity, 5 kGy may be necessary to completely inactivate protozoan oocysts
• Bacteria


  • Salmonella spp.
  • Campylobacter
  • Escherichia coli
  • Shigella
  • Vibrio spp.
  • Listeria monocytogenes
  • Clostridium botulinum
  • Clostridium perfringens
  • Bacillus cereus
  • Staphylococcus aureus
• Salmonella


  Salmonellosis, S. enterica subsp. typhimurium, S. enterica subsp. enteritidis, Enteric fever (typhoid/paratyphoid), S. enterica subsp. typhi, S. enterica subsp. paratyphi, Carrier - They contract only mild or asymptomatic disease, Approximately 3% of persons infected with S.typhi and 0.1% of those infected with non typhoidal salmonellae become chronic carriers, These cases serve as natural reservoir, Mary Mallon was the first famous carrier of typhoid fever
• Campylobacter


  Leading cause of bacterial diarrhea, Campylobacteriosis, Very few deaths, Microaerophilic, Spiral, curved rods, Campylobacteriosis caused by include unpasteurized milk, water, undercooked poultry, Found in the GIT of livestock, poultry and other animals including pets, Clinical signs include diarrhea, abdominal cramps, fever, nausea, Duration: 2-5 days, Can lead to Guillain-Barré Syndrome, Leading cause of acute paralysis, Develops 2-4 weeks after Campylobacter infection
• Escherichia coli


  Enterohemorrhagic E coli (EHEC), E. coli O157:H7, Signs include watery or bloody diarrhea, nausea, cramps, Onset: 2-5 days, Duration: 5-10 days, Sequel: Hemolytic Uremic Syndrome (HUS), Acute kidney failure in children, Life threatening
• Shigella


  Shigellosis /Bacillary dysentery, Shigella sonnei, S. dysenteriae, S. boydii, S. flexneri, Shiga toxin & enterotoxin, GIT of humans and higher primates, Signs: Watery or bloody diarrhea, nausea, vomiting, cramps, fever, Duration: 5-7 days
• Vibrio spp.


  Vibrio cholerae: Cholera, Infective dose: one million organisms must be ingested to cause illness, produce cholera toxin, Vibrio parahaemolyticus: unidentified toxin, Vibrio vulnificus: septicaemic invasive infection
• Listeria monocytogenes


  Listeriosis, Symptoms: influenza-like symptoms with persistent fever, Complications: septicemia, meningitis (or meningoencephalitis), encephalitis, intrauterine or cervical infections in pregnant women - spontaneous abortion or stillbirth
• Clostridium botulinum


  Neurotoxin, Botulism, Signs: Dizziness, Double vision, drooping eyelids, difficulty speaking and swallowing, Onset: 18-36 hours
• Clostridium perfringens


  Toxin mediated infection, Clostridium perfingens enterotoxin (CPE), heat-labile (74 °C), Signs: Dizziness, Double vision, drooping eyelids, difficulty speaking and swallowing, Onset: 8-22 hours
• Bacillus cereus


  Intoxication & Toxin mediated infection, Emetic toxin (ETE): 1 to 6 h, Enterotoxins: 8 to 16 h, HBL, Nhe, Signs: Diarrhea and vomiting
• Staphylococcus aureus


  Staphylococcus food poisoning/ Staphylo-enterotoxicosis/ staphylo-enterotoxemia, Infective dose--a toxin dose of less than 1.0 µg in contaminated food, This toxin level: population > 100,000 per gram, Onset time: 2-6h
• Norwalk-like Viruses


  Norovirus; Caliciviridae family, 23 million cases annually, Small infectious dose, Signs: 12-48 hours post-exposure, Nausea, vomiting, diarrhea, abdominal cramps, Headache, low-grade fever, Duration: 2-3 days
• Hepatitis A virus


  Hepatitis A (HA) or type A viral hepatitis, The infectious dose is unknown but presumably is 10-100 virus particles, Symptoms: a mild illness characterized by sudden onset of fever, malaise, nausea, anorexia, and abdominal discomfort, followed in several days by jaundice
• BSE - Bovine Spongiform Encephalopathy


  "MAD COW DISEASE", Prion proteins, Highly stable, resisting freezing, drying and heating at normal cooking temperatures, pasteurization and sterilization, No test can detect, long incubation period of up to several years (3-8), Variant Creutzfeldt-Jakob disease (vCJD), Transmissible, slowly progressive, degenerative, fatal disease, The practice of feeding cattle rendered animal parts, November 1986 UK