Ewen C. D. Todd

1
What We Can Learn from the Role of the Food
Worker in Outbreaks

• Ewen C. D. Todd
• Advertising, Public Relations and Retailing
• Michigan State University
• Train the Trainer Workshop at the International
  Food Safety Conference
• Dubai, February 2009

2
What Have We Learned from Investigation of
Outbreaks Where Food Workers Were Implicated?
3
Impact of the Infected Food Worker

• CDC estimates 76 million cases of foodborne
  illness each year in the United States
• Estimated that between 18-20 of foodborne
  illness associated with an infected food worker
  in the US, and 7 of salmonellosis in the UK
• Thus, there may be up to 13-15 million cases in
  the US associated with an infected food worker
  (18-20 of 76 million)

4
Definition of Food Worker

• The term food worker is used in this context to
  describe individuals, who harvest, process,
  prepare and serve food
• It is broader in context than food handler
  although the two terms are used interchangeably
  in the literature and investigative reports

5
Purpose of Study of Infected Food Workers
Implicated in Outbreaks

• Project of the Committee on Control of Foodborne
  Illness (CCFI) of the International Association
  for Food Protection (IAFP)
• Goal to develop an understanding of the dynamics
  of transmission of infectious agents to and from
  the food worker in a variety of settings
• The CCFI approached the task with the premise
  that all foodborne illness is fundamentally
  preventable and that by influencing human
  behavior there will be fewer opportunities for
  spread of infectious disease agents by workers
  and others

6
Papers Prepared on Outbreaks Where Food Workers
Have Been Implicated in the Spread of Foodborne
Disease in the Journal of Food Protection
(2007-2009)

• Part 1 Description of the problem, methods and
  agents involved
• Part 2 Description of outbreaks by size,
  severity, and settings
• Part 3 Factors contributing to outbreaks and
  description of outbreak categories
• Part 4 Infective doses and pathogen carriage
• Part 5 Sources of contamination and pathogen
  excretion from infected persons
• Part 6 Transmission and survival of pathogens in
  the food processing and preparation environment
• Part 7 Barriers and sanitizers in reducing
  contamination
• Part 8 Hand hygiene

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8
Outbreaks by Geographical Region
9
Summary of Data on Pathogens

• 816 outbreak reports with 80,682 cases
• Pathogens in order of frequency
• norovirus/probable norovirus (338)
• Salmonella enterica (151)
• hepatitis A virus (84)
• Staphylococcus aureus (53)
• Shigella spp (33)
• Streptococcus pyogenes Group A (17)
• Parasites Cyclospora, Giardia, and
  Cryptosporidium (23)

10
Outbreaks by Food Category
Commodity
11
Foods Associated with Outbreaks Where Food
Workers Were Implicated

• Multiple foods and multi-ingredient foods were
  noted most frequently
• Salads, including potato, pasta and coleslaw (92)
• Sandwiches (74)
• Chinese, Mexican type food, and pizza (19)
• Hors doeuvres and other RTE cold snacks with
  sauces and glazes (8)

12
Outbreaks by Settings

Mainly restaurants
13
Most Extreme Outbreaks

• Largest outbreak
• 6350 cases 1987, North Carolina S. sonnei
• Largest number hospitalized
• 396 1998, Brazil S. aureus
• Largest number of deaths
• 68 1990, Mozambican refugees in Malawi V.
  cholerae

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1 Single worker causes an outbreak that affects
patrons
2b Offsite food worker(s) infects other workers
at a different location
6 Food contaminated by offsite workers
2a, 4a, 4b, 5 Multiple workers cause outbreak at
the same location (2a), through contamination of
food (4a), no clear source (4b), or workers may
be the victims (5)
3a, 3b Foods contaminated by infected worker are
temperature abused leading to outbreak
8 Worker(s) are infected but deny illness and
outbreaks not reported as caused by infected
worker(s)
7 Infected consumers (patrons, families,
institutional residents, etc) likely source of
infectious agent
Ill Consumers (Patrons, Families, Institutional
Residents, etc)
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Social Gathering and Staphylococcus aureus

• 8,000 people gathered in a community to celebrate
  a Catholic priests ordination in 1998 in Brazil
• After eating food provided, 4,000 were acutely
  ill and 2,000 hospitalized, 16 died
• Eight food workers began preparing the chicken,
  roast beef, rice, and beans over 48 h on the
  Friday before the event, and stored in aluminum
  containers at room temperature until Sunday
  morning
• These food workers had positive fingernail swabs
  for Staphylococcus aureus, and five of them had
  the same strain isolated from their nasopharynxes
• Leftover food was also found to contain S. aureus
  at 2.0 x 108 CFU/g, which produced 6 µg of
  enterotoxin A/g

17
Social Gathering and Staphylococcus aureus

• 8,000 people gathered in a community to celebrate
  a Catholic priests ordination in 1998 in Brazil
• After eating food provided, 4,000 were acutely
  ill and 2,000 hospitalized, 16 died
• Eight food workers began preparing the chicken,
  roast beef, rice, and beans over 48 h on the
  Friday before the event, and stored in aluminum
  containers at room temperature until Sunday
  morning
• These food workers had positive fingernail swabs
  for Staphylococcus aureus, and five of them had
  the same strain isolated from their nasopharynxes
• Leftover food was also found to contain S. aureus
  at 2.0 x 108 CFU/g, which produced 6 µg of
  enterotoxin A/g

18
Examples of S. aureus Outbreaks

• 2 handlers sores on hands, 5 handlers same strain
  in nose
• S. aureus isolated from infected cut on hand of
  person who baked cake
• 11 hospitalized S. aureus isolated from stool,
  vomitus, sandwich and infected finger of food
  handler, sandwiches stored 8-10 hours without
  refrigeration
• S. aureus in food and on food handler, inadequate
  storage temperature for 5 hours
• S. aureus phage 6 patients and 6 food handlers,
  infected cut on hand of one food worker who mixed
  food ingredients with bare hands
• Cook handled and cooked ham with open cuts, sores
  and finger lesion
• Contamination from hand of a symptomatic food
  worker, stored at inappropriate temperature

19
School Children and Norovirus

• 3,236 (41.5) of 7,801 schoolchildren and 117
  (39.4) of 297 teachers were ill in Japan in 1989
  after eating catered food
• Food had been provided by a catering company to
  nine elementary schools
• Workers had bare-hand contact with the food, and
  a worker reported symptoms of gastrointestinal
  illness on the day the food was prepared

20
School Children and Norovirus

• 3,236 (41.5) of 7,801 schoolchildren and 117
  (39.4) of 297 teachers were ill in Japan in 1989
  after eating catered food
• Food had been provided by a catering company to
  nine elementary schools
• Workers had bare-hand contact with the food, and
  a worker reported symptoms of gastrointestinal
  illness on the day the food was prepared

21
Frosted Cakes Leading to Norovirus Infections

• A bakery worker in Minnesota in 1982 prepared 76
  litres of frosting using his arm up to the elbow
  to break sugar lumps and scrape the sides of the
  vat
• There were subsequently 3,000 cases of norovirus
  infection
• He had five episodes of diarrhea and two of
  vomiting during his 6-h shift when he frosted the
  cakes
• Also he had sick children at home

22
Frosted Cakes Leading to Norovirus Infections

• A bakery worker in Minnesota in 1982 prepared 76
  litres of frosting using his arm up to the elbow
  to break sugar lumps and scrape the sides of the
  vat
• There were subsequently 3,000 cases of norovirus
  infection
• He had five episodes of diarrhea and two of
  vomiting during his 6-h shift when he frosted the
  cakes
• Also he had sick children at home

23
Giardiasis from Salad

• In 1990, a food worker in the cafeteria of a
  large Connecticut insurance company was infected
  with Giardia lamblia and used her bare hands
  while slicing raw vegetables, causing 27 cases of
  giardiasis
• She tested positive and had used gloves for most
  food preparation activities but not for salad bar
  items
• The investigators noted that the outbreak was
  probably only detected because the affected
  individuals were insurance company employees
  whose medical care was administered by a single
  health management team

24
Giardiasis from Salad

• In 1990, a food worker in the cafeteria of a
  large Connecticut insurance company was infected
  with Giardia lamblia and used her bare hands
  while slicing raw vegetables, causing 27 cases of
  giardiasis
• She tested positive and had used gloves for most
  food preparation activities but not for salad bar
  items
• The investigators noted that the outbreak was
  probably only detected because the affected
  individuals were insurance company employees
  whose medical care was administered by a single
  health management team

25
Hepatitis at a Resort

• In 2004, a large outbreak with 351 hepatitis A
  cases occurred involving tourists at a specific
  hotel in the Egyptian resort city of Hurghada
• Guests who developed HAV infection after their
  vacation were 2.6 times more likely to have
  ingested orange juice than were healthy controls
• None of the hotel staff in Egypt was positive
• The juice was not pasteurized and came from a
  site where hygiene problems were identified
• Although an infected worker at the juice
  production company was the most likely source,
  none of the company staff was IgM positive, but
  staff members often changed and were not
  available for testing

26
Hepatitis at a Resort

• In 2004, a large outbreak with 351 hepatitis A
  cases occurred involving tourists at a specific
  hotel in the Egyptian resort city of Hurghada
• Guests who developed HAV infection after their
  vacation were 2.6 times more likely to have
  ingested orange juice than were healthy controls
• None of the hotel staff in Egypt was positive
• The juice was not pasteurized and came from a
  site where hygiene problems were identified
• Although an infected worker at the juice
  production company was the most likely source,
  none of the company staff was IgM positive, but
  staff members often changed and were not
  available for testing

27
Norovirus in a Restaurant (1)

• In Michigan in 2006, 364 restaurant patrons
  became ill with norovirus GI illness after dining
  at a restaurant where employees had reported to
  work while ill
• On Jan 28, a line cook vomited at home before
  reporting to work at 1100 a.m. and then vomited
  again into a waste bin beside the frontline
  workstation at approximately 200 p.m. while
  preparing antipasti platters, pizzas, and salads
• After vomiting, he remained on site (but off the
  cooking line) and left work at 415 p.m.
• This cook also reported to work on Jan 29 from
  1100 a.m. to 430 p.m. while still experiencing
  loose stools
• Because of the open physical layout of the
  restaurant, no barrier impeded airborne spread of
  the virus from the kitchen to the main dining area

28
Norovirus in a Restaurant (2)

• There was a significant association between the
  platter and the ill persons
• Patron attack rates increased after the cook
  vomited and among employees, particularly cooks
  vs. servers, who worked on Jan 28
• The investigation revealed deficiencies in
  employee hand washing practices, cleaning and
  sanitizing of food and nonfood contact surfaces,
  temperature monitoring and maintenance of
  potentially hazardous food, and maintenance of
  hand-sink stations for easy accessibility and
  proper use
• A quaternary ammonium based sanitizer normally
  used to clean the restaurant was ineffective
  against the norovirus
• Then, a bleach solution used to disinfect the
  restrooms and all surface areas within at least a
  25-ft radius of the vomiting site was effective
  for preventing further illnesses

29
Norovirus in a Restaurant (1)

• In Michigan in 2006, 364 restaurant patrons
  became ill with norovirus GI illness after dining
  at a restaurant where employees had reported to
  work while ill
• On Jan 28, a line cook vomited at home before
  reporting to work at 1100 a.m. and then vomited
  again into a waste bin beside the frontline
  workstation at approximately 200 p.m. while
  preparing antipasti platters, pizzas, and salads
• After vomiting, he remained on site (but off the
  cooking line) and left work at 415 p.m.
• This cook also reported to work on Jan 29 from
  1100 a.m. to 430 p.m. while still experiencing
  loose stools
• Because of the open physical layout of the
  restaurant, no barrier impeded airborne spread of
  the virus from the kitchen to the main dining area

30
Norovirus in a Restaurant (2)

• There was a significant association between the
  platter and the ill persons
• Patron attack rates increased after the cook
  vomited and among employees, particularly cooks
  vs. servers, who worked on Jan 28
• The investigation revealed deficiencies in
  employee hand washing practices, cleaning and
  sanitizing of food and nonfood contact surfaces,
  temperature monitoring and maintenance of
  potentially hazardous food, and maintenance of
  hand-sink stations for easy accessibility and
  proper use
• A quaternary ammonium based sanitizer normally
  used to clean the restaurant was ineffective
  against the norovirus
• Then, a bleach solution used to disinfect the
  restrooms and all surface areas within at least a
  25-ft radius of the vomiting site was effective
  for preventing further illnesses

31
Norovirus from Salad

• In 2000, a catered meal and distributed to 52 car
  dealerships in the US as a reward for high car
  sales was responsible for multiple
  gastroenteritis outbreaks in 13 states, resulting
  in at least 333 cases
• Pasta salads from one caterer was strongly
  associated with illness
• Pasta was placed in large plastic bins, other
  ingredients were added, and food workers mixed
  the salad by immersing their ungloved arms up to
  the elbow
• Although the workers denied any history of
  illness in the preceding week, 2 of 15 employees
  had elevated IgA antibody titres to norovirus
• This caterer had been cited by health inspectors
  for multiple sanitary code violations and was
  temporarily closed pending sanitary improvements

32
Norovirus from Salad

• In 2000, a catered meal and distributed to 52 car
  dealerships in the US as a reward for high car
  sales was responsible for multiple
  gastroenteritis outbreaks in 13 states, resulting
  in at least 333 cases
• Pasta salads from one caterer was strongly
  associated with illness
• Pasta was placed in large plastic bins, other
  ingredients were added, and food workers mixed
  the salad by immersing their ungloved arms up to
  the elbow
• Although the workers denied any history of
  illness in the preceding week, 2 of 15 employees
  had elevated IgA antibody titres to norovirus
• This caterer had been cited by health inspectors
  for multiple sanitary code violations and was
  temporarily closed pending sanitary improvements

33
Characteristics of Pathogens
34
Infectivity of Pathogens Transmitted by Infected
Food Workers
IT Intestinal Tract, RT Respiratory Tract, F
Feces, N Nasal Secretions, S Skin/Skin
Lesions, U Urine, V Vomitus
35
Foodborne Pathogens Transmitted by Infected Food
Worker and Periods of Infectivity
Time After Exposure (Days)
0
50
100
150
200
250
300
Norovirus (SRSV/NLV)
Hepatitis A
Salmonella spp.
S. Typhi/Paratyphi
Shigella spp.
Staphylococcus aureus
Streptococcus pyogenes
Giardia lamblia
Campylobacter jejuni
Cryptosporidium parvum
Vibrio cholerae
E. coli O157H7
Yersinia enterocolitica
Incubation
Incubation/ Pre-symptomatic
Pre-symptomatic Shedding Phase
Extended Symptomatic
Symptomatic Period
Post-symptomatic Phase
Extended Post-symptomatic Phase
Carrier State
36
Levels of Pathogens in Body Excretions

• Salmonella in feces
• Ill or early convalescence 105-107 CFU/g
• Late excretion (infants excrete longer) 100-103
  CFU/g
• 10-19 days after illness 100-106 CFU/g
• 69-102 days after illness 100-104 CFU/g
• Sneeze with Streptococcus pyogenes
• up to 106 CFU/sneeze
• up to 500 CFU/154 cm2 1.5 9.5 feet from sneeze
  source
• HAV in feces just before hepatitis symptoms begin
• 108 infectious particles/g
• Norovirus in feces while ill
• 105 1010 copies/g
• Cryptosporidium in one bowel movement 108 109
  oocysts

37
Fecal Contamination of Hands During Toilet Use
With and Without Toilet Paper

• Mean fecal weight/hand (g) after cleansing
• Without toilet paper 8.5 x 10-6 - 9.8 x 10-7
• With toilet paper 5.0 x 10-9
• Pathogens can be present in feces at levels of
  from 105 to 1011 per g. A tenth of a milligram
  of fecal material (10-4 g), an amount barely
  perceptible, might contain up to a million
  infectious bacterial cells or viral particles
• At 10-7 g fecal matter of contamination per hand
  and a pathogen that present at 1011 per g, if
  hands were washed and/or sanitized, a 2 to 3 log
  reduction (99-99.9) could still allow a worker
  to transmit a few cells
• Add to the fact that those ill may be more
  careless with fecal cleanliness (continual
  cleanup from diarrhea, fecal accidents, and not
  focused on the job and hygienic practices), and
  the risk increases greatly

38
Survival of Enteric Pathogens on Hands and
Surfaces
39
Survival of Pathogens

• Norovirus survived in carpets and toilet
  facilities for more than one day after an
  individual vomited on seats and washroom
  infected clean-up crew and subsequent concert
  hall attendees infected by aerosols
• Illnesses from carpet removers in a hospital ward
  12 days after vomiting outbreak occurred
• Pathogens tend to survive longer on surfaces such
  as ceramic tile, steel, dust, glass and plastic
  than on hands

40
Levels of Pathogens in Raw Meat and Poultry
41
Transfer of Organisms from Hands

• The transfer efficiency between hands and lettuce
  was found to be 0.3 and from hands to spigots
  was 1
• The transfer rate of HAV from fingerpads of adult
  volunteers to pieces of fresh lettuce was
  determined to be 9 of the infectious load on the
  fingers
• Lettuce touched by a washed hand may be
  contaminated with as many as 3.8 log10 CFU
  indicator bacteria
• A 10 transfer rate of bacteria from food to
  hands or bare hand to food and by using gloves,
  this rate was reduced to 0.01

42
Outbreaks Associated with Lack of Adequate
Hygienic Facilities

• Inadequate toilet facilities (Yersinia,
  Shigella,Vibrio, Salmonella)
• Non functional toilet (Shigella)
• Lack of handwashing facilities (Shigella,Vibrio,
  HAV)
• Inadequate handwash facilities (Shigella,
  norovirus)
• Difficult to use faucets (HAV)
• Lack of running water (Yersinia, Shigella,Vibrio)
• Lack of fingernail brush (Giardia)
• Lack of soap (Shigella,Vibrio, Giardia)
• No paper towels for hand drying (Shigella,
  Salmonella, norovirus)

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Handwashing Occasions

• Wash hands thoroughly with disinfectant soap and
  water at appropriate times for the job
  description
• Also after the following
• handing raw foods
• after going to the toilet
• after contact with persons suffering from acute
  GI symptoms
• after being in contact with infants and
  incontinent individuals

45
Minimize Hand Contact

• Evaluate food handling procedures and modify to
  reduce or eliminate hand contact for RTE food
• Gloves
• Utensils
• Deli papers

46
Exclusion and Work Restrictions

•  Exclude infected symptomatic persons (GI) from
  preparing and serving food during communicable
  periods of illness
• Exclude infected persons known to be asymptomatic
  carriers based on screening
• Restrict food workers from preparing or serving
  food
• Infected skin lesions
• Sore throat
• Acute respiratory infections
• Food workers should be kept on sick leave for 48
  h following disease cessation

47
Hygiene Education, Training and Supervision

• Train food workers and supervisors
• in proper food handling practices and procedures
• to report personal and family illness
• Provide supervision of workers
• Surveillance of workers and correction of
  handling errors
• Screen food workers (nasal and stool)
• at start of employment
• routine testing
• upon return from travel in area having high
  endemic disease rates
• Immunize workers when feasible (HAV, etc)

48
What Have Investigations of Outbreaks Where Food
Workers Were Implicated Taught Us - Sources?

• There are many sources where food workers have
  become infected
• Ill family members, homosexual partners or
  diapering a sick child
• Intravenous drug use
• Eating contaminated food
• Environmental sources, e.g., water, animals
• Travel abroad
• Contact with other infected workers

49
Spread in the Food Worker Environment

• Once a worker has brought an agent into a food
  operation, it can easily be transferred from
  person to person, person to food contact surfaces
  and to food
• Lack of adequate handwashing facilities and
  improper handwashing and drying
• Long and artificial nails are too difficult to
  clean effectively
• Lesions and wounds harboring pathogens are not
  properly covered
• Workers continuing to work when infected and ill
  (diarrhea and vomiting) management or worker
  decision
• Transmission between workers in food preparation
  area
• Lack of use of gloves/bare hand contact

50
Removal of Contaminants

• Fecal contamination can be extensive even after
  washing use of toilet paper doesnt prevent all
  fecal organisms from going on finger tips and
  from there to contact surfaces
• Vomiting can spread viral particles over long
  distances despite any clean up afterwards and
  particles can persist for days or weeks
• Thorough and frequent handwashing and use of
  gloves keeps contamination in food environment to
  a minimum

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Some Problems To Be Resolved

• Having incentives for workers to stay home when
  they are ill or diagnosed with a likely infection
• Identifying workers who are asymptomatic and need
  to be away from handling food and any physical
  contact with other workers
• Effective communication with low-paid workers,
  often speaking other languages than English, may
  not read well and will move on for a continual
  turnover, issues of trust and motivation
• Putting more resources into effective local
  investigation of outbreaks
• More priorities for handwashing in industry/home

52
Acknowledgements

• Bert Bartelson, Judy Greig, and Barry Michaels,
  members of the Committee for the Control of
  Foodborne Illness, International Association for
  Food Protection (IAFP), and IAFP Board

53
QUESTIONS?
54
Categorization of Outbreaks Where Food Workers
Were Implicated

• 3. After food worker(s) contaminates food via
• 3a) fecal contamination (e.g., by Salmonella,
  Shigella, Yersinia) or
• 3b) through skin, nose and throat contamination
  (e.g., Streptococcus pyogenes, Staphylococus
  aureus)
• Temperature abuse results in bacterial
  multiplication resulting in high enough numbers
  to cause illness

55
Categorization of Outbreaks Where Food Workers
Were Implicated

• 4. Multiple food workers are
• 4a) unequivocally the cause of the outbreak
  though contamination of food or food contact
  surfaces, or
• 4b) linked to an outbreak but there is no clear
  initiating source
• 5. Food worker(s) becomes infected but uncertain
  whether they are victims or causes of outbreak

56
Categorization of Outbreaks Where Food Workers
Were Implicated

• 6. Food contaminated with pathogens by offsite
  workers and delivered to the location where the
  outbreak occurs by directly infecting
  consumers/patrons
• Details of the worker contribution to the
  contamination are usually not known

57
Categorization of Outbreaks Where Food Workers
Were Implicated

• 7. Patrons (those being served), not workers, are
  the probable source of the infectious agent
  though contamination of food or food contact
  surfaces
• 8. Outbreaks where workers are implicated
  epidemiologically and likely are infected or
  colonized but deny illness

58
Category 1Single Worker Causes an Outbreak

• 37 cases associated with cold salad bar items
  from the cafeteria of a Minnesota college, 2000
• Index case a symptomatic food worker
• Called in sick but symptoms resolved later that
  day
• Returned to work the next day and worked the
  remainder of the week in salad bar section, with
  extensive bare-hand contact of salad items
• Noroviral agent based on epidemiological
  information
• Call-in ill log useful to determine dates that
  employees were ill and to ascertain the
  responsible employee

59
Category 2aMultiple Workers Cause Outbreak

• Multi-state outbreak of Salmonella Thompson 78
  cases at fast food restaurants and catered events
• Full-time employee did not wear gloves and
  handled every individual bread item at least
  twice
• Worked with symptoms for 4 days until overnight
  hospitalization
• Resumed work after discharge and continued
  working until termination of employment
• She infected brother who also worked with dough
  and bread
• No formal training on safe food-handling
  practices
• Many employees spoke only Spanish but had English
  procedure manuals

60
Category 2b Offsite Food Worker(s) Infects
Workers at a Different Location

• HAV affected 40 university students, 11
  employees of two restaurants, and 11 other
  residents in Arizona, 1973
• Two distinct epidemic waves at the 2 restaurants
• Index case of first restaurant prepared salads
• Index case of the second restaurant had eaten at
  the first restaurant
• Implicated vehicles at the second restaurant
  included guacamole, green salad, spaghetti, and
  hamburger

61
Category 3a Foods Fecally Contaminated by
Infected Worker are Temperature Abused Leading to
Outbreak

• July 1981 New York Y. enterocolitica O8
  isolated from 37 persons including head cook and
  kitchen staff
• Five hospitalized for appendicitis
• Powdered milk and dispenser contaminated when
  food workers cleaned and repaired a broken spigot
• Same strain isolated from chow mein indicating
  multiple contamination scenarios
• Reconstituted milk held 24 hours under cool
  conditions but allowed growth of Yersinia

62
Category 3bFoods Nasally Contaminated by
Infected Worker are Temperature Abused Leading to
Outbreak

• Convention in Florida 1979 outbreak of
  pharyngitis, 72/231 ill, including waiters and
  cooks
• Streptococcus pyogenes Group G isolated from 10
  of 16 with pharyngitis and 1 of 41 who did not
• Illness associated with chicken salad
• Cook prepared chicken salad a day prior to her
  symptoms
• Cooked chicken refrigerated overnight in a deep
  container
• No indication she wore gloves or washed hands
  frequently
• Opportunity for growth of the Streptococcus

63
Category 3b Foods Contaminated by Lesion of
Infected Worker and are Temperature Abused
Leading to Outbreak Commercial Travel

• Flight attendant and 196 passengers rapidly
  developed vomiting and diarrhea following
  ingestion of ham and cheese omelets served during
  a chartered flight for a tour group from Tokyo to
  Paris, stopping en route in Alaska and Denmark
• Cook who prepared ham had infected finger
• Ham left at room temperature for six hours
• S. aureus isolated from food samples

64
Category 4a Multiple Food Workers are
Unequivocally the Cause of the Outbreak

• 2000 multi-state outbreak, 333 cases, catered
  meal prepared in Ohio and distributed to 52 car
  dealerships nationwide
• Consumption of any of four side salads strongly
  associated with illness
• Ingredients were placed in large plastic bins and
  mixed by food workers who immersed ungloved arms
  up to the elbow
• 2 of 15 employees had elevated norovirus titers
• Three food handlers were symptomatic before
  outbreak

65
Category 4b Multiple Food Workers are Linked to
Outbreak But There is No Clear Initiating Source

• July 1992, 46 patrons at 21 restaurants in
  Michigan and one in Ohio infected with Shigella
  flexneri
• Associated with consumption of pre-prepared
  salads from a central commissary
• 15 infected workers ill during the same time
  period and four prepared salad during the
  outbreak period
• Salad was mixed with bare hands, bagged by
  machine, and employees added or subtracted from
  the bags to meet the weight standard
• Investigation failed to identify the infected
  employees

66
Category 5 Food Worker(s) Become Infected but
Uncertain Whether They Are Victims or Cause of
Outbreak

• Large outbreak of shigellosis associated with a
  mass gathering in a national forest area, North
  Carolina, 1987
• Over 50 of 12,700 attendees infected
• Transmission assumed to be by food and water,
  followed by person-to-person contact
• Food prepared in 47 communal kitchens with
  limited sanitation
• Food from at least one kitchen implicated and
  unboiled water drunk by attendees

67
Category 6Food Contaminated With Pathogens by
Offsite Workers and Delivered to the Location
Where the Outbreak Occurs
.

• Six norovirus outbreaks (1,143 cases) in
  institutions or commercial catering settings,
  June to Sept. 2005 in Denmark, linked to frozen
  raspberries imported from Poland
• Unheated frozen raspberries served one day before
  start of each outbreak
• Estimated 400 elderly people affected and at
  least 23 hospitalized
• Three different norovirus serotypes isolated
• Several independent contamination events likely
  occurred
• Infected workers in the harvesting or processing
  of the raspberries in Poland were a likely but
  not proven source

68
Category 7 Patrons Are the Source of the
Infectious Agent Though Contamination of Food or
Food Contact Surfaces.

• Mediterranean-style restaurant in Melbourne,
  Australia, three successive norovirus outbreaks,
  May 1998 - June 1999
• Food served on platters and patrons ate with
  fingers, moving from table to table
• Different norovirus strains isolated in the three
  outbreaks indicating no reservoir but recurring
  contamination of food
• Demonstrates how norovirus can be transmitted
  where many people are in close contact and touch
  and eat food

69
Category 8 Outbreaks Where Workers Are
Implicated but They Deny Illness

• Minnesota 2004 six relatives complained of GI
  illness after dining at a restaurant
• 1 of 6 positive for norovirus
• None of the workers were obviously symptomatic
• Most of the staff were Spanish speaking and the
  manager acted as translator
• Conclusion outbreak could not be adequately
  characterized even though the likely source of
  the norovirus was one or more employees

70
Examples of Streptococcus Outbreaks

• Military base 3 food handlers of boiled egg
  salad were asymptomatic carriers of Streptococcus
  hand contamination or sneezing
• Military base an egg salad preparer tested
  positive, he shelled boiled eggs with bare hands
  for the salad
• School food preparer had open hand lesion that
  came in direct contact with the macaroni and
  cheese
• Catered event preparer of egg salad had extreme
  cellulitis on hands he tasted the salad, workers
  coughed or sneezed

71
Examples of Hepatitis A Outbreaks

• Salads
• Restaurant two asymptomatic pantry workers
  contaminating food by hand shredding lettuce and
  dipping fingers into dressing to taste them
• Caterer Salad boy with apparent good hygiene
  hand-tore moist lettuce and soon developed fever
  and malaise
• Drinks
• Employee, who was HAV positive but asymptomatic,
  was a suspected IV drug user, and had helped
  prepare fountain drinks and sandwiches
• Bar tender had chronic diarrhea and contaminated
  the glasses when served beverages
• Asymptomatic carrier did not wash his hands after
  using the toilet and contaminated the punch at a
  catered event 

72
Examples of Hepatitis A Outbreaks

• Fast food restaurant food worker, who was a drug
  user and family described him as having poor
  hygiene, had diarrhea and tested positive for HAV
• Caterer Asymptomatic sandwich maker had prior
  nausea and vomiting, most likely contamination
  through hand contact with foods
• Caterer Pastry-cook had jaundice prior to
  preparing pastries by bare hand for meals
• Bakery bakers assistant with hepatitis was
  directly involved in handling and dipping cooked
  pastries

73
Examples of Shigella Outbreaks

• University Shigella infections after eating
  shrimp deveined in India contamination source
  uncertain but has to be human fecal
• Restaurant employees ill with Shigella flexneri
  prepared tossed salad by reaching into chopped
  salad ingredients with bare hands
• Restaurant worker infected with Shigella after a
  trip to Mexico washed lettuce with bare hands
• Restaurant worker infected with Shigella
  flexneri in restaurant with hygiene violations,
  including a lack of hand washing between tasks
  and inadequate handwashing facilities

74
Examples of Salmonella Outbreaks

• Salmonella enteritidis on curly fried potatoes
  and ice handled bare-handed by employee who had
  onset of illness 1 day prior, no paper towels
• Prison Inmate who deboned turkey had multiple
  excoriated lesions on both forearms that had a
  positive S. aureus culture, Salmonella infantis
  isolated from turkey eaters

75
Examples of Norovirus Oubreaks

• Salad asymptomatic noroviral shedding by one or
  more of the workers who handled lettuce with bare
  hands
• RTE food hand preparation by untrained staff and
  patients
• Catered function food worker excreted the virus
  and touched RTE foods including melon
• Cruise ship ice machine did not have proper
  air-gap device to prevent sewage backup, and the
  ice was contaminated by hands of those scooping
  it out
• Bakery A cake decorator, ill with GI, was
  wearing long artificial nails with which she
  contaminated the icing
• Restaurant bad management forced employee to
  work, who was sick and wanted to stay home, used
  bare hands on hamburgers

76
Examples of Outbreaks Associated with Bare Hand
Contact

• Restaurants
• Bare hands serving pineapple slices, not ill at
  the time, but ill 3 hours after handling
• Asymptomatic worker with no gloves sliced meats,
  cheese and vegetables, no adequate washing area
• Symptomatic worker prepared guacamole and salsa
  with bare hands, good hand washing facilities
• Employee excreting virus while using bare hands
  to remove tissues from steamed bovine heads
• Bakeries
• Soiled hands not washed due to painful skin
  lesions
• Contaminated baked goods when applying sugar
  glaze with bare hands
• Deli shop
• 76 year old grandmother typhoid carrier handled
  cannelloni without gloves after they were cooked
  once a week

77
Data Sources

• Outbreak data from 1927 to 2004 from
• Michigan (2000-2003) State line listings
• Minnesota (1999-2004) State line listings and
  outbreak reports
• New York (1985-2000) State line listings
• Washington (1990-2003) State line listings and
  outbreak reports
• Health Canada (1976-1996) Line listings from
  annual reports of foodborne and waterborne
  disease outbreaks
• Outbreak reports from other countries
• Published peer-reviewed literature including
  reviews

78
Large Gathering and Shigellosis

• For 2 weeks, food was prepared in 47 communal
  kitchens in a national forest area for a Rainbow
  gathering in North Carolina in 1987
• There were no toilets, hand washing facilities,
  safe drinking water sources, or refrigeration
• The outbreak began on July 4 1987, and rapidly
  spread throughout the gathering until it was
  closed on July 15 with a total of 6350 cases
• Transmission was assumed to be by food, water,
  and person-to-person contact.
• Secondary infections occurred after ill persons
  returned to home communities in other parts of
  the US

79
Cake and Norovirus

• A cake requiring direct hand contact during its
  preparation was associated with the majority of
  illnesses in an outbreak of 2700 persons in 2002
  in Massachusetts
• At least two bakery employees experienced
  norovirus-compatible illness during the week
  preceding the weddings. Two wedding guests, a
  wedding hall employee, and one of the bakery
  employees were ill identical sequence types were
  detected in the stool specimens submitted

80
Shigellosis from Hamburgers in a Resort

• A butcher who prepared hamburger patties at a
  resort in Haiti in 1984 had a Shigella flexneri
  infection and continued working while ill during
  the 3-week period in which 1,136 guests reported
  illness
• Illnesses were linked only to those who consumed
  raw or rare hamburger this was followed by
  secondary person-to-person spread between
  roommates

81
Categorization of Outbreaks Where Food Workers
Were Implicated

• 1. Single food worker causes an outbreak though
  contamination of food or food contact surfaces
• 2. Single food worker infects other workers
  (victims) who in turn infect consumers/patrons
  though contamination of food or food contact
  surfaces
• a) in the same establishment or
• b) in a separate location

82
Transfer of Organisms from Hands

• Study using Nalidixic acid-resistant Enterobacter
  aerogenes as a surrogate for an enteric pathogen
  to follow cross-contamination demonstrated that
  after handling chicken, contaminated hands
  transferred 2.4 to 5.7 log10 of bacteria to a
  spigot used to wash hands after washing 1.9 to
  6.5 log10 still remained on hands (Chen et al.
  2001)
• Perez et al. (2006) showed that there was a high
  risk with the use of the same gloves to handle
  contaminated chicken meat and then slice ham
  compared to the safer use of different gloves to
  handle each product

83
Listeria monocytogenes in Different
Cross-contamination Scenarios (Perez et al., 2006)

• A series of cross contamination scenarios at
  retail were ranked according to their risk level
• The highest risk corresponded to the use of the
  same gloves to handle contaminated chicken meat
  and then sliced ham compared to the safer use of
  different gloves to handle each product
• The lowest risk corresponded to use of gloved
  hands but washed between handling the chicken and
  slicing the ham (only 250/100,000 slices would be
  contaminated)
• All scenarios were capable of ham reaching levels
  above 108 cfu/g after storage when growth can
  occur
• Lack of knowledge of transfer rates provided the
  model with an important uncertainty component

84
Simulated Distribution of L. monocytogenes at the
Time of Consumption (N) for 3 Scenarios Perez et
al., 2006)
85
Effective Handwashing                

• Wash, rinse, dry
• Fingernail brush
• Instant hand sanitizer
• Frequent (Task appropriate)
• Minimize cross-contamination-use handsfree
  devices, e.g., turn on tap/faucet
• Paper towel dispensers/hot air drying/doorless
  entry or automatic doors
• Handwash process monitored, documented and
  verified (MDV)

86
Studies on Handwashing

• Thumbs, palms, spaces between fingers, and
  fingertips including the fingernail area, are
  areas in which contamination is most likely to
  remain. Hand drying may help make up for
  deficiencies in the washing process
• E. coli and Pseudomonas fluorescens mixed with
  ground beef and rubbed onto hands were 95
  removed with a single handwashing using an E1
  soap
• a 75 reduction was subsequently shown with a tap
  water wash only
• Giardia was removed form the hands with soap and
  handwashing. When 10,000 cysts were placed in
  the palm of the hand, handwashing eliminated 99
  (100 cysts)

87
Studies on Handwashing

• Based on laboratory testing using artificial
  contaminants, the effectiveness of handwashing,
  including washing, rinsing and drying, ranged
  from 2 to 3 log10 reduction (99-99.9)
• Compliance rates for handwashing are estimated at
  50 but no surveys have been done

88
Food Preparation and Environmental Control

• Follow proper cooking, hot holding, chilling and
  storage procedures
• Environmental controls
• Disinfect surfaces often
• Clean change of work clothing

89
Airflight Illnesses

• 1. British Airways flights in 1984 with a total
  of 866 cases 631 passengers, 135 aircrew, and
  100 catering personnel and loaders, with 2
  passenger deaths
• An ill chef prepared the aspic glaze, which was
  then left at ambient temperatures
• Also, it was reported that a party given by a
  senior catering manager at the catering center
  resulted in all guests becoming ill, with two
  hospitalized
• 2. Charter flights to and from Canary Islands to
  Finland in 1976 resulted in 1,800 salmonellosis
  cases
• Salmonella Typhimurium phage type 96 was isolated
  from passengers, mayonnaise, and one food worker
  in the Las Palmas catering establishment

90
Airflight Illnesses

• 1. British Airways flights in 1984 with a total
  of 866 cases 631 passengers, 135 aircrew, and
  100 catering personnel and loaders, with 2
  passenger deaths
• An ill chef prepared the aspic glaze, which was
  then left at ambient temperatures
• Also, it was reported that a party given by a
  senior catering manager at the catering center
  resulted in all guests becoming ill, with two
  hospitalized
• 2. Charter flights to and from Canary Islands to
  Finland in 1976 resulted in 1,800 salmonellosis
  cases
• Salmonella Typhimurium phage type 96 was isolated
  from passengers, mayonnaise, and one food worker
  in the Las Palmas catering establishment