1 / 93

FOODBORNE ZOONOSES

FOODBORNE ZOONOSES Over 250 diseases can be caused by contaminated food or drink most are bacterial ( Salmonella and Campylobacter) or caused by Norwalk virus most cases are single cases, not associated with a recognized food-borne outbreak

benjamin
Download Presentation

FOODBORNE ZOONOSES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. FOODBORNE ZOONOSES • Over 250 diseases can be caused by contaminated food or drink • most are bacterial (Salmonella and Campylobacter) or caused by Norwalk virus • most cases are single cases, not associated with a recognized food-borne outbreak • majority of food items are raw or undercooked products of animal origin (meat, dairy, poulty, seafood) • ~ 500 outbreaks reported each year

  2. FOODBORNE ZOONOSES • Foodborne illness a substantial problem in US • 6.5 to 33 milliion cases annually • ~9000 deaths • Since 1986, of ~3200 outbreaks reported, only 21 were associated with contaminated produce • Reporting of food- and water-borne diseases began over 50 years ago as investigations of enteric fevers

  3. FOODBORNE ZOONOSES

  4. FOODBORNE ZOONOSES • Major virulence determinants: • toxins - destroy, damage, inactivate natural defense mechanism of host • exotoxins • endotoxins • enzymes - assist bacteria in establishing infection and producing disease

  5. FOODBORNE ZOONOSES Toxins • exotoxins • secreted from cell or leak out after cell death • soluble protein, thus readily carried through body by lymphatics or blood • damage at distant site, usually specific • normally destroyed by heating to 100º C., although some are resistant to boiling (S. aureus) • non-pyrogenic • example: botulinism toxin, Staphylococcus aureus

  6. FOODBORNE ZOONOSES Toxins • endotoxins • produced only by gram negative bacteria • part of the outer cell wall (lipopolysaccharide coat) • lipid A component is toxic • side chains (O, H antigen) are immunogenic • released in large amounts at cell death • heat stable, not destroyed by autoclaving • less potent and less specific than exotoxins

  7. FOODBORNE ZOONOSES Toxins • endotoxins • pyrogenic • toxic to most animals, producing similar range of biological effects regardless of source • fever • increased WBC • DIC (disseminate intravascular coagulopathy) • hypotension • shock • death • degraded by oxidizing agents • examples: E. coli, Salmonella, Shigella

  8. FOODBORNE ZOONOSES Enzymes • spreading factors • hyaluronidase (gram +) - attacks interstitial cement of connective tissue • collagenase (Clostridium) - break down collagen, facilitating invasion of muscle and gas gangrene formation • neuraminidase (Vibrio and Shigella) - break down intercellular cement of intestinal epithelial cells • kinase (Strep and Staph) - digests fibrin, preventing clotting and allowing rapid diffusion

  9. FOODBORNE ZOONOSES Enzymes • cell lysis • hemolysins (Staph, Strep, and Clostridia) • lecithinases (C. perfringens) • phospholipases (C. perfringens) -  toxin • coagulase (Staph) - causes clotting • adenylate cyclase activity - bacterial toxins having immediate (short-range) effects that promote invasion • Ex: anthrax toxin - edema factor

  10. FOODBORNE ZOONOSES New challenges • newly identified pathogens (emerging pathogens) • newly identified vehicles of transmission • changes in food production • changes in food distribution • decline in food safety awareness

  11. FOODBORNE ZOONOSES Reasons for emergence or re-emergence • changes in pathogen • centralized and concentrated production • globalization of food supply • increase in “at risk” populations • changes in food animal practices • changes in type and volume of foods imported • now import over 30 billion tons of food annually • change in dietary preferences and exposure has led to many more types of produce being introduced

  12. FOODBORNE ZOONOSES Surveillance programs • Foodborne Disease Active Surveillance Network (FoodNet) by CDC-EIP • collaboration with USDA, FDA • to determine incidence of foodborne illness in US • established in 7 locations: • California (selected counties) • Connecticut (selected counties) • Georgia (selected counties) • Minnesota (entire state) • Oregon (entire state) • New York (selected counties) • Maryland (selected counties)

  13. FOODBORNE ZOONOSES Surveillance programs • FoodNet (continued) • to document effectiveness of Hazard Analysis and Critical Control Points Rule (HACCP) • active surveillance • population survey • physician survey • case-control study of E. coli O157:H7

  14. FOODBORNE ZOONOSES Surveillance programs • Antimicrobial resistance surveillance • PulseNet - network set up for molecular subtyping • pulsed-field gel electrophoresis method for E. coli O157:H7 now available in 24 state laboratories, along with USDA and FDA • rapid comparison of PFGE profiles with database at CDC • already been critical in outbreak investigation in Colorado associated with ground beef and multi-state investigation traced to alfalfa sprouts • Basic research at NIH • establish virulence mechanisms and develop prevention tools

  15. FOODBORNE ZOONOSES Surveillance programs • Enter-Net (formerly Salm-Net) • European Commission funded • Established for surveillance for Salmonella and E. coli infections • Includes 15 European countries • has already let to public health interventions and product recalls in Europe

  16. FOODBORNE ZOONOSES • Escherichia coli O157:H7 • Campylobacter spp. (jejuni; fetus ssp. fetus) • Listeria monocytogenes • Salmonella spp. (Enteriditis; Typhimurium) • Yersinia enterocolitica; Y pseudotuberculosis

  17. Escherichia coli • gram-negative rod-shaped bacteria • hundreds of strains • most strains are harmless, normal intestinal flora of healthy humans and animals • occurrence: ubiquitous, worldwide distribution

  18. Categories of Escherichia coli causing diarrhea • enterohemorrhagic (EHEC - hemorrhagic colitis; O157:H7) • enterotoxigenic (ETEC- traveler’s diarrhea) • enteroinvasive (EIEC - dysentery-like) • enteropathogenic (EPEC - infant diarrhea) • enteroaggregative (infant d. in underdeveloped countries) • diffuse-adherence (pediatric diarrhea)

  19. Escherichia coli O157:H7 • first recognized in 1982 outbreak of hemorrhagic diarrhea traced to hamburgers (fast food chain) • estimated 10,000 to 20,000 cases/yr in the US • outbreaks have been associated with other foods such as leaf lettuce, cider, contaminated water • more commonly isolated than Shigella

  20. Escherichia coli O157:H7 • “O” and “H” designation refer to cell surface antigen markers that are used to distinguish serotypes • Other serotypes of enterohemorrhagic strains may also be implicated (O26:H11; O111:H8; O104:H21)

  21. Escherichia coli O157:H7 • syndrome caused by potent cytotoxins: verotoxins 1 and 2 (Shiga-like toxins I and II because resemble toxins of Shigella dysenteriae) • may also produce hemolytic-uremic syndrome • although recognized and intensively studied for 15 years, still do not know best method of treatment nor how animals become infected

  22. Escherichia coli O157:H7 • Microbiological features and identification • most enterohemorrhagic (EHEC) strains of E. coli do not ferment sorbitol (MacConkey-sorbitol media used for screening O157:H7) • presence of Shiga-like toxins • serotyping (phage typing)

  23. Escherichia coli O157:H7 • Microbiological features and identification • identification of toxin genes by DNA probes • presence of virulence plasmid (plasmid allows expression of a fimbria, attachment to the intestinal mucosa) • does not grow well or at all at 44-45ºC

  24. Escherichia coli O157:H7 Epidemiological features • Reservoir: • cattle especially young dairy cattle • wild ruminants - deer (?) • humans

  25. Escherichia coli O157:H7 Epidemiological features • Transmission: • ingestion of contaminated foods • usually inadequately cooked beef (especially ground beef) • raw milk • other foods by cross-contamination--lettuce, apple cider, apple juice • person-person (families, child care facilities, institutions) • waterborne (swimming in crowded areas, drinking water)

  26. Escherichia coli O157:H7 Epidemiological features • Incubation period: • relatively long, ranging from 3-8 days • Period of communicability: • <1 week in adults • may be up to three weeks in children • prolonged carriers uncommon

  27. Escherichia coli O157:H7 Epidemiological features • Susceptibility and resistance • very low infectious dose • old-age appears to be a risk factor • children < 5 years of age are at greatest risk of developing hemolytic-uremic syndrome

  28. Escherichia coli O157:H7 Epidemiological features • Occurrence • important cause of foodborne disease in US, UK, Europe, Japan, South Africa, southern regions of South America, Australia • importance in underdeveloped regions and rest of world not established

  29. Escherichia coli O157:H7 Clinical features • diarrhea ranging from mild, non-bloody to virtually • straight bloody stool, abdominal cramping • fever is infrequent

  30. Escherichia coli O157:H7 Clinical features • Hemolytic-uremia syndrome • more common in children • may occur in up to 10% of cases • characterized by: • hemolytic anemia • thrombocytopenia • renal failure (common cause of renal failure in children)

  31. Escherichia coli O157:H7 Clinical features • Thrombotic thrombocytopenic purpura (TTP) in elderly • Case fatality rate: 3-5% (up to 50% in elderly with TTP)

  32. Escherichia coli O157:H7 Control methods • Preventive measures to reduce incidence • slaughterhouse management to minimize contamination of meat by intestinal contents • pasteurization of milk and dairy products • irradiate beef, especially ground beef

  33. Escherichia coli O157:H7 Control methods • preventive measures to reduce incidence • adequately cook meat to a temp of 155°F (68°C) • ‘pink all gone’ does not mean necessarily safe - cooking with meat thermometer is recommended • protect, purify, chlorinate public water supplies for drinking • chlorination of swimming pools • adequate hygiene in day-care facilities

  34. Escherichia coli O157:H7 Control methods • control of patient and immediate environment • report to health department (mandatory in many states) • isolation: because of extremely small infective dose, patients should not be allowed to handle food or provide child/patient care until 2 negative samples are obtained • disinfection • contacts with diarrhea should be handled as if infected (no food handling, no patient care or child contact) until two negative fecal samples are obtained

  35. Escherichia coli O157:H7 Control methods • treatment • fluid/electrolyte replacement • antibiotic treatment uncertain; TMP-SMX may lead to hemolytic-uremia syndrome

  36. Campylobacter enteritis Background • Significant cause of enteritis worldwide and of traveler’s diarrhea in U.S. • Leading cause of bacterial diarrhea in U.S. • Campylobacter 45% • Salmonella 30% • Shigella 17% • E.coli O157:H7 5% • Most common isolate: C. jejuni (C. fetus ssp. jejuni)

  37. Campylobacter enteritis Microbiology • Campylobacter jejuni; C. colio, C. fetus ssp. fetus, C. spp. • many biotypesand serotypes occur; useful in epidemiology • gram-negative, microaerophillic, motile rods • distinct shape of organism, flagella useful in identification • require special environmental conditions for optimal growth • 5% O2 • prefers relatively high concentration of CO2 • relatively fragile, sensitive to stresses such as oxygen, drying, heat, acidic conditions

  38. Campylobacter enteritis Microbiology Gram stain from culture media (Note slender, curved rods)

  39. Campylobacter enteritis Clinical features • watery diarrhea, sometimes with blood (occult) • normally self-limiting, not requiring treatment • most common in children (<5 yrs) and young adults (15-29 yrs of age) • low fatality rate--usually in immunocompromised • infective dose small (~500 organisms in some cases) • toxin production may cause diarrhea

  40. Campylobacter enteritis Epidemiology • Occurrence: estimated 2 - 4,000,000 cases/yr in US, probably more • Reservoir: • poultry and cattle primarily; also pets, swine, and other species • common contaminant of raw poultry (20-100% at retail) • can exist in intestinal tract of people and animals without causing symptoms • present in high numbers in stools of infected symptomatic individuals

  41. Campylobacter enteritis Epidemiology • Mode of transmission: • vehicles: • undercooked meat • contaminated food and water • raw milk • direct contact: pets, farm animals, infected infants • person-person uncommon

  42. Campylobacter enteritis Prevention and control • On the farm: good sanitary practices (USDA guidelines) • In the plant: HACCP1 to minimize opportunity for spread • At retail: recall policy on ready-to-eat meat and poultry products found to be contaminated enforced by USDA (similar for E. coli O157:H7) • Consumer: proper food handling procedures in kitchen 1 HACCP = Hazard Analysis and Critical Control Point

  43. Campylobacter enteritis Prevention and control • CDC report: 80% of US outbreaks due to Campylobacter could be prevented with universal pasteurization of milk and proper treatment of drinking water • improved handling of chicken important • bacteria destroyed when meat/poultry reach internal temperature of 160º F • freezing not reliable method for destroying organism but thorough cooking will render product safe

  44. Campylobacter enteritis Outbreaks • Usually outbreaks are small (< 50 individuals) • Vermont: 2,000 people ill from temporary use of non-chlorinated water supply • 1986 outbreak in school children traced back to milk which was being pasteurized for 135º F for 25 minutes rather than the required 145º F for 30 minutes (LTLT) • Note: 161º F for 15 seconds (HTST) 280º F for 2 seconds (ultra-pasteurized)

  45. SALMONELLOSIS • Causative organisms: primarily S. enteriditis, typhimurium in U.S. • numerous serotypes, many are pathogenic to both animals and man • of the ~2,000 serotypes known, only ~200 recognized in the U.S. • discovered in 1880, genus named for American scientist Salmon in honor of his extensive work

  46. SALMONELLOSIS • Microbiological features and identification • gram-negative rod-shaped bacteria • motile (non-motile forms are S. gallinarium, pullorum) • heat labile • growth prevented at <7º C for most serotypes • non-spore forming, but can survive for long periods in foods and other substrates • can survive for long periods in foods with low aw (water activity) such as chocolate, peanut butter, black pepper)

  47. SALMONELLOSIS Epidemiology - reservoir • ubiquitous • found in a wide range of animals, particularly poultry, swine, cattle, pets (iguanas, turtles, terrapins, tortoises, chicks, dogs, cats), humans • chronic carriers common in animals and birds, less so in humans • S. enteriditis infects ovaries of healthy appearing hens, thereby contaminating eggs in oviduct before shell is formed

  48. SALMONELLOSIS Epidemiology - reservoir • S. typhi, paratyphi - man only • S. typhimurium - animals, particularly food animals • S. enteriditis - animals, particularly food animals • S. dublin - cattle • S. choleraesuis - swine • S. gallinarum, pullorum - poultry • S. arizonae - animals, reptiles

  49. SALMONELLOSIS Epidemiology - mode of transmission • ingestion of raw, undercooked, or contaminated food • meat, milk, eggs, produce • fecal-oral transmission • contact with pets (especially infants) • foods contaminated by infected food handler • outbreaks usually traced to food items

  50. SALMONELLOSIS Epidemiology - disease frequency • incidence highest in infants and young children • estimated 5 million cases annually (US) • up to 80% are sporadic cases • large outbreaks in hospitals, restaurants, institutions are common • largest outbreak in US (25,000 cases) resulted from a nonchlorinated municipal water supply

More Related