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Are we really what we eat? Listeria and foodborne illnesses McMaster Mini-Medical School Dr. Cheryl Main.

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Presentation on theme: "Are we really what we eat? Listeria and foodborne illnesses McMaster Mini-Medical School Dr. Cheryl Main."— Presentation transcript:

1 Are we really what we eat? Listeria and foodborne illnesses McMaster Mini-Medical School Dr. Cheryl Main

2 Objectives To review some common causes of food borne illness – Listeria – E. Coli O157:H7 – Campylobacter – Salmonella – Norovirus To discuss prevention strategies for these infections To review the protection practices in Canada

3 The Canadian experience The Public Health Agency of Canada estimates Canadians suffer from million cases of foodborne illness per year

4 How can foods make us sick? Preformed toxins (1-6 hrs) – Staphylococcus aureus – Bacillus cereus Bacterial/viral infection(12-24hrs or longer) – Salmonella – Shigella – Campylobacter – Norovirus and many others

5 Listeria monocytogenes Bacteria found in the environment Can contaminate prepared meats, unpasteurized milk and soft cheeses Patients who are immunocompromised, pregnant women and young children are at highest risk of infection

6 Listeria monocytogenes Outbreaks have been associated with: – Cold meats, soft cheeses – Hot dogs – Smoked salmon – Undercooked meats – Raw alfalfa sprouts – Raw fish, shellfish – Unpasteurized juice – Foods made with uncooked eggs (Caesar salad, egg nog)

7 Listeria monocytogenes Maternal infection – flu-like illness, fever, malaise, diarrhea, meningitis, sepsis Infants – prematurity, pneumonia, sepsis granulomatosis infantisepticum – rash, disseminated granulomas

8 Listeria monocytogenes Diagnosis: bacterial culture from blood, spinal fluid Treatment: ampicillin + gentamicin (10-21 days)

9 Listeria monocytogenes Prevention: Persons at risk for Listeria should avoid eating Soft cheeses (feta, brie, Camembert, blue) Leftover ready to eat foods or reheat until steaming before eating Avoid cold cuts or reheat before eating thoroughly cook all food from animal sources wash raw vegetables keep uncooked meat separate from vegetables

10 E. Coli O157:H7 Bacteria normally in the colons of cows and deer Named for it’s somatic (O) and flagellar (H) antibodies Highly pathogenic in humans Produces a toxin (shiga-like toxin) Patients develop bloody diarrhea, abdominal pain Self-limited (5-10 d)

11 E. Coli O157:H7 The infectious dose is low (100 bacteria) Person-to-person spread occurs in outbreaks Incubation period 10hr-6 days, usually 3-4 days The bacteria can be isolated from stool Public Health is notified of all cases

12 Outbreaks Hamburger Unpasteurized apple cider Raw vegetables, spinach, tomatoes Salami Yogurt Contaminated water

13 Prevention Cook ground beef fully – juices run clear Do not drink unpasteurized milk or apple cider Good handwashing Keep meats separate from vegetables Watch for food recalls

14 Treatment E.Coli O157:H7 Do not give antibiotics! Supportive management May require hospitalization HUS may require hemodialysis

15 Traveler’s diarrhea PHAC reports up to 50% of travelers to an endemic area for 2 weeks or longer will get this Up to 20% will spend one or more days in bed Caribbean and in Eastern and Southern Europerisk varies from 15% to 20% Africa, Southeast Asia, and Latin America risk ranges from 20% to 50%

16 Traveler’s diarrhea Most cases are due to other E. Coli strains (ETEC) Transmitted through food and water with fecal contamination Produces watery diarrhea Self-limited lasts 3days-1 week Incubation period is 1-3days

17 Traveler’s diarrhea-Treatment Supportive Antibiotics - septra (trimethoprim- sulfamethoxazole) or fluoroquinolones (ciprofloxacin, levofloxacin, ofloxacin) reduce symptom duration by 1-3 days May be taken as a single dose or 3-5 day course Peptobismol

18 Traveler’s diarrhea-Prevention Drink only bottled water and carbonated beverages Boil or peel all foods Avoid ice in drinks, salads, unpeeled fruits Vaccine – reduces risk of E. Coli travelers’s diarrhea by 50%, traveler’s diarrhea by <25% Indications for vaccine are immunocompromise, GI abnormalities or those unable to tolerate the self-limited diarrhea

19 Boil it, Peel it, Cook it or FORGET IT!

20 Fowl or Foul Improperly cooked chicken is a common source of food borne illness Campylobacter Salmonella E. Coli O157:H7

21 Campylobacter jejuni The most common foodborne infection in North America A comma shaped bacteria Causes abdominal pain, malaise, fever Diarrhea may contain blood Can mimic appendicitis Usually self-limited, with more people improving within one week Occasionally illness is severe or prolonged

22 Campylobacter jejuni Normally found in the intestines of birds Can be found in a wide assortment of meats Farm animals and pets can be carriers The incubation period is 1-7 days Diagnosed on routine bacterial culture of stool

23 Campylobacter jejuni Sources of outbreaks: Improperly cooked poultry, eggs Contaminated/untreated water Unpasteurized milk Contact with infected persons/animals

24 Campylobacter jejuni Treatment: Rehydration Antibiotics for 5-7 days: – Erythromycin – Azithromycin – Tetracycline – only use in children >8 years old – Fluoroquinolone (ciprofloxacin, levofloxacin, ofloxacin) if > 18 years old

25 Campylobacter jejuni-Prevention Handwashing – esp. after handling raw poultry Avoid contact of meat/eggs with raw fruits and vegetables Pasteurize milk Proper water treatment Fully cook raw poultry and proper handling before cooking Food handlers should not work while ill

26 Salmonella A bacteria which can cause diarrhea, abdominal pain, cramps, bloodstream infection or asymptomatic carriage Reservoirs are poultry, livestock, reptiles (pet turtles, iguanas) Incubation period is 6-72 hours Infection is usually self-limited (5-7 days)

27 Salmonella Sources of infection Improperly cooked/handled poultry Unpasteurized milk Raw eggs Contaminated water Alfalfa sprouts, ice cream, rice, fruits and vegetables

28 Salmonella - Treatment Rehydration Antibiotics not used in those at low risk for complications If bacteremia or infant < 3 months old, immunocompromised patient treat with: – Ampicillin, Septra (trimethoprim- sulfamethoxazole), Ceftriaxone, ciprofloxacin <18

29 Salmonella - Prevention Good handwashing especially if in contact with raw poultry or reptiles Fully cook poultry and eggs Pasteurize milk Proper water treatment Food handlers cannot work when ill

30 Salmonella typhi Causes “typhoid fever” Gastroenteritis, bacteremia, abdomenal pain, hepatosplenomegaly Only found in humans Usually acquired during foreign travel from consumption of contaminated food or water

31 Noroviruses Several people who attended a funeral all become ill with vomiting and diarrhea They notify public health of their illness The funeral was catered by an external catering company Food consisted of cut fruit and sandwiches Further investigation revealed the same caterer provided food for 2 other funerals and reports of similar illness from those in attendance

32 Noroviruses Small, highly infectious virus Causes nausea and vomiting within hours of ingestion Very low infectious dose (10 virus particles) Patients continue to shed virus for up to 2 weeks after recovering from the illness Stable at cold temperatures, buffet cold foods are a common source of infection Causes 50% of food borne outbreaks No treatment available – rehydrate and rest

33 Norovirus - Prevention Good handwashing Avoid common sources – shellfish, salads, ice cookies, water, sandwiches, fruit Wash fruits and vegetables thoroughly before eating Eat food that is cooked and still hot Thoroughly clean all contaminated surfaces well

34 What is Canada doing to protect us In Canada the responsibility for foodborne illnesses falls to – Local public health departments – Hospitals – Infection Control – Regional Health Authorities – Provincial Government – Federal government – Public Health Agency of Canada

35 What is Canada doing to protect us Programs in place in Canada to monitor food borne infections: – Center for Infectious Disease Prevention and control within PHAC – Canadian Field Epidemiology Program – PulseNet Canada – National Enteric Surveillance Program – Canadian Food Inspection Agency

36 For more information see and look in Food Safety, Travel Health and Infectious Diseases sections


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