Transcript Are we really what we eat? Listeria and foodborne illnesses

Are we really what we eat?
Listeria and foodborne illnesses
McMaster Mini-Medical School
Dr. Cheryl Main
Objectives
• To review some common causes of food borne
illness
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Listeria
E. Coli O157:H7
Campylobacter
Salmonella
Norovirus
• To discuss prevention strategies for these
infections
• To review the protection practices in Canada
The Canadian experience
• The Public Health Agency of Canada estimates
Canadians suffer from 11-13 million cases of
foodborne illness per year
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...............
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
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)
Listeria monocytogenes
• Maternal infection – flu-like illness, fever,
malaise, diarrhea, meningitis, sepsis
• Infants – prematurity, pneumonia, sepsis
• granulomatosis infantisepticum – rash ,
disseminated granulomas
Listeria monocytogenes
• Diagnosis: bacterial culture from blood, spinal
fluid
• Treatment: ampicillin + gentamicin (10-21
days)
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
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)
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
Outbreaks
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Hamburger
Unpasteurized apple cider
Raw vegetables, spinach, tomatoes
Salami
Yogurt
Contaminated water
Prevention
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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
Treatment E.Coli O157:H7
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Do not give antibiotics!
Supportive management
May require hospitalization
HUS may require hemodialysis
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%
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
Traveler’s diarrhea-Treatment
• Supportive
• Antibiotics - septra (trimethoprimsulfamethoxazole) 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
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
Boil it, Peel it, Cook it or FORGET IT!
Fowl or Foul
Improperly cooked chicken is a common source
of food borne illness
• Campylobacter
• Salmonella
• E. Coli O157:H7
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
Campylobacter jejuni
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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
Campylobacter jejuni
Sources of outbreaks:
• Improperly cooked poultry, eggs
• Contaminated/untreated water
• Unpasteurized milk
• Contact with infected persons/animals
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
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
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)
Salmonella
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Sources of infection
Improperly cooked/handled poultry
Unpasteurized milk
Raw eggs
Contaminated water
Alfalfa sprouts, ice cream, rice, fruits and
vegetables
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 (trimethoprimsulfamethoxazole), Ceftriaxone, ciprofloxacin <18
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
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
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
Noroviruses
• Small, highly infectious virus
• Causes nausea and vomiting within 16-72
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
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
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
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
• For more information see
www.publichealth.gc.ca and look in Food
Safety, Travel Health and Infectious Diseases
sections