Title: Ewen C. D. Todd
1What 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
2What Have We Learned from Investigation of
Outbreaks Where Food Workers Were Implicated?
3Impact 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)
4Definition 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
5Purpose 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
6Papers 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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8Outbreaks by Geographical Region
Geographical Region Number of Outbreaks () Number of Cases ()
USA 647 (79.3) 54,888 (68.0)
Europe 63 (7.7) 7,694 (9.5)
Canada 62 (7.6) 3,320 (4.1)
Australia/Asia 27 (3.3) 4,680 (5.8)
Latin America/Caribbean 6 (0.7) 5,408 (6.7)
Africa 4 (0.5) 2,394 (3.0)
Middle East 3 (0.4) 400 (0.5)
Multiple Countries 2 (0.2) 1,843 (2.3)
Unknown 2 (0.2) 55 (0.1)
Totals 816 (100) 80,682 (100)
9Summary 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)
10Outbreaks by Food Category
Commodity
11Foods 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)
12Outbreaks by Settings
Mainly restaurants
13Most 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
141 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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16Social 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
17Social 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
18Examples 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
19School 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
20School 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
21Frosted 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
22Frosted 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
23Giardiasis 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
24Giardiasis 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
25Hepatitis 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
26Hepatitis 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
27Norovirus 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
28Norovirus 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
29Norovirus 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
30Norovirus 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
31Norovirus 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
32Norovirus 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
33Characteristics of Pathogens
34Infectivity of Pathogens Transmitted by Infected
Food Workers
Agent Incubat-ion Period In Days (mean) Carriage (C) Rates Reported () Presymp-tomatic Shedding Time (days) Sympto-matic Period (Days) Post-sympt-omatic Shedd-ing (days) Asymp-tomatic Overall Period of Infect-ivity (days) Source of Infectious Material Carriage/ Shedding
Norovirus 0.6-3.2 GI 1.1-1.5 Control 0.2 1.5? 1-11 2 weeks 32 May be gt2 weeks IT, F, RT, V
HAV 10-50 (28) 0.01 in population 10-14 7-14 21 (180) 8 (70 in elderly) Up to 8 weeks F, U
Salmon-ella 0.25-10 GI0-16 Control 0.1-1.6 X 7-10 4-22 weeks 0.23-10 19 for FWs in DCs Up to years IT, F
Shigella 0.5-6 GI 0-0.8 X 4-7 60-150 55 - 75 Up to years IT, F
S. aureus 2-6 hours 20-36 C C C 20 - 65 Years N, S, C
Giardia lamblia 3-25 (7) GI0.4-16 X 7-60 Up to 35 (children) Months IT, F
IT Intestinal Tract, RT Respiratory Tract, F
Feces, N Nasal Secretions, S Skin/Skin
Lesions, U Urine, V Vomitus
35Foodborne 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
36Levels 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
37Fecal 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
38Survival of Enteric Pathogens on Hands and
Surfaces
Infective Agent Surfaces Log, Loss or Half Life
Salmonella Enteritidis in egg white and yolk Hands, inoculated eggs, formica surface, utensils Survived well 24 hrs.
Shigella sonnei Fecally- contaminated hands Survival for 3 hrs.
S. aureus Skin and clothing 1 log/5 hrs.
Campylobacter jejuni Hands with peptone, chicken broth, and 50 blood 3-7 log/ 2 min. 6 log/ 15 min. 6 log/ 45 min.
E. coli Skin 3 log/5 min.
E. coli in milk Fingertip 94 loss in 45 min.
Entamoeba histolytica Hands (nails in feces) Survival for 45 min.
39Survival 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
40Levels of Pathogens in Raw Meat and Poultry
Infective Agent Product Log 10 CFU
Campylobacter jejuni Chicken juices, ceca Chicken carcasses 103-109 lt101-109
E. coli O157H7 Ground beef Cattle/sheep feces 5 103-105
Salmonella Chicken juices, organ, carcasses Chicken fillets 102-106 lt10 with up to 103
41Transfer 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
42Outbreaks 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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44Handwashing 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
45Minimize Hand Contact
- Evaluate food handling procedures and modify to
reduce or eliminate hand contact for RTE food - Gloves
- Utensils
- Deli papers
46Exclusion 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
47Hygiene 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)
48What 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
49Spread 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
50Removal 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
51Some 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
52Acknowledgements
- 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
53QUESTIONS?
54Categorization 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
55Categorization 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
56Categorization 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 -
57Categorization 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
58Category 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
59Category 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
60Category 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
61Category 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
62Category 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
63Category 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
64Category 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
65Category 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
66Category 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
67Category 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
68Category 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
69Category 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
70Examples 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
71Examples 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
72Examples 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
73Examples 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
74Examples 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
75Examples 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
76Examples 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
77Data 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
78Large 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
79Cake 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
80Shigellosis 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
81Categorization 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
82Transfer 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
83Listeria 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
84Simulated Distribution of L. monocytogenes at the
Time of Consumption (N) for 3 Scenarios Perez et
al., 2006)
85Effective 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)
86Studies 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)
87Studies 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
88Food Preparation and Environmental Control
- Follow proper cooking, hot holding, chilling and
storage procedures - Environmental controls
- Disinfect surfaces often
- Clean change of work clothing
89Airflight 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
90Airflight 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