Download 3. Foodborne and suspected foodborne disease

Enhancing Foodborne Disease
Surveillance Across Australia
Government of Western Australia
Department of Health
Public Health and Clinical Services
Communicable Disease Control Directorate
OzFoodNet
Foodborne Disease Surveillance and
Outbreak Investigations in Western
Australia, Second Quarter 2013
Acknowledgments
Acknowledgement is given to the following people for their assistance with the activities
described in this report: Mr Brian MacKenzie, Ms Lyn O’Reilly, Ms Jenny Green, Mr Ray
Mogyorosy and the staff from the enteric, PCR and food laboratories at PathWest
Laboratory Medicine WA; Mr Stan Goodchild, Mrs Anna Anagno and other staff from the
Food Unit of the Department of Health, Western Australia; Public Health Nurses from
metropolitan and regional Public Health Units; and Local Government Environmental
Health Officers.
Contributors/Editors
Nevada Pingault, Barry Combs and Robyn Gibbs
Communicable Disease Control Directorate
Department of Health, Western Australia
PO Box 8172
Perth Business Centre
Western Australia 6849
Email: [email protected]
Telephone: (08) 9388 4999
Facsimile:
(08) 9388 4877
Web:
OzFoodNet WA Health
www.public.health.wa.gov.au/3/605/2/ozfoodnet_enteric_infections_reports.pm
OzFoodNet Department of Health and Ageing
www.ozfoodnet.gov.au/
Disclaimer:
Every endeavour has been made to ensure that the information provided in this document
was accurate at the time of writing. However, infectious disease notification data are
continuously updated and subject to change.
This publication has been produced by the Department of Health, Western Australia.
1
Executive summary
During the second quarter 2013, the Western Australian (WA) OzFoodNet team conducted
surveillance of enteric diseases, undertook investigations into outbreaks and was involved
with ongoing enteric disease research projects. Campylobacter notifications were 21%
lower compared to the five year average for this quarter; while notifications of Salmonella
and Cryptosporidium were 28% and 142% higher, respectively. Investigations were
conducted into three foodborne disease outbreaks, with 12 identified cases of illness.
OzFoodNet also conducted surveillance of 21 non-foodborne outbreaks. Of these, 18
outbreaks were attributed to person-to-person transmission, with most caused by
norovirus infection, and involving a total of 433 people ill. There were also three outbreaks
with an unknown mode of transmission. The WA OzFoodNet team participated in
numerous national OzFoodNet working groups and/or investigations.
2
Table of contents
Executive summary ...........................................................................................................2
1.
Introduction .................................................................................................................4
2.
Incidence of notifiable enteric infections .................................................................5
3.
Foodborne and suspected foodborne disease outbreaks ......................................7
4.
Cluster investigations ................................................................................................9
5. Non-foodborne disease outbreaks and outbreaks with an unknown mode of
transmission ....................................................................................................................11
5.1. Person-to-person outbreaks .................................................................................11
5.2. Outbreaks with unknown mode of transmission....................................................11
6.
Site activities .............................................................................................................12
7.
References ................................................................................................................13
List of Tables
Table 1. Enteric disease notifications for the 2nd quarter of 2013, and comparison to
the mean number for the 2nd quarter for the years 2008 to 2012 .................................6
Table 2. Foodborne outbreaks, 2nd quarter 2013 ...........................................................9
Table 3. Cluster investigations in WA, 2nd quarter 2013 .............................................11
Table 4. Outbreaks of non-foodborne transmission in WA, 2nd quarter 2013 ...........12
3
1. Introduction
It has been estimated that there are 5.4 million cases of foodborne illness in Australia
each year and that the cost of this illness is estimated at $1.2 billion per year1. This is
likely to be an underestimate of the cost of enteric illness in Australia as not all enteric
infections are caused by foodborne transmission. Other important modes of transmission
include person-to-person, animal-to-person and waterborne transmission. Importantly,
most of these infections are preventable through interventions at the level of primary
production, commercial food handling, households and institutional infection control.
This report describes enteric disease surveillance and investigations carried out in the
second quarter of 2013 by OzFoodNet WA and other WA Department of Health (WA
Health) units. Most of the data are derived from notifications to WA Health of 16 enteric
diseases by doctors and laboratories. In addition, outbreaks caused by non-notifiable
enteric infections are also documented in this report, including norovirus, which causes a
large burden of illness in residential care facilities (RCF) and the general community.
OzFoodNet WA is part of the Communicable Disease Control Directorate (CDCD) within
WA Health, and is also part of the National OzFoodNet network funded by the
Commonwealth Department of Health and Ageing 2. The mission of OzFoodNet is to
enhance surveillance of foodborne illness, including investigating and determining the
cause of outbreaks. OzFoodNet also conducts applied research into associated risk
factors and develops policies and guidelines related to enteric disease surveillance,
investigation and control. The OzFoodNet site based in Perth is responsible for enteric
disease surveillance for the whole of WA.
OzFoodNet WA regularly liaises with staff from Public Health Units (PHUs), the Food Unit
in the Environmental Health Directorate of WA Health; and the Food Hygiene, Diagnostic
and Molecular Epidemiology laboratories at PathWest Laboratory Medicine WA.
PHUs are responsible for public health activities, including communicable disease control,
within their respective administrative regions. The PHUs monitor RCF gastroenteritis
outbreaks and provide infection control advice. The PHUs also conduct follow up of single
cases of important enteric diseases including typhoid, paratyphoid and hepatitis A.
4
The Food Unit liaises with Local Government (LG) Environmental Health Officers (EHO)
during the investigation of outbreaks, particularly those involving food businesses. The
Food Hygiene, Diagnostic and Molecular Epidemiology laboratories at PathWest
Laboratory Medicine WA provide public health laboratory services for the surveillance and
investigation of enteric disease.
2. Incidence of notifiable enteric infections
Enteric disease notifications were extracted from the Western Australian Notifiable
Infectious Diseases Database (WANIDD) by optimal date of onset (ODOO) for the time
period 1 April 2008 to 30 June 2013. The ODOO is a composite of the ‘true’ date of onset
provided by the notifying doctor or obtained during case follow-up, the date of specimen
collection for laboratory notified cases, and when neither of these dates is available, the
date of notification by the doctor or laboratory, or the date of receipt of notification,
whichever is earliest.
In the second quarter of 2013, Campylobacter infection was the most commonly notified
enteric disease in WA, with 361 notifications, 21% lower than the second quarter mean for
the previous five years (n=454) (Table 1). This was due to a 29% decrease in both locally
acquired (n=166) and overseas acquired (n=39) cases, compared with the mean for the
previous five years (234 and 55 cases, respectively).
The second most commonly notified enteric infection in the second quarter of 2013 was
Salmonella, with 328 notifications, which was 28% higher than the mean number of
notifications for this quarter for the previous five years (n=256) (Table 1). This was
attributed to an increase in both locally acquired and overseas acquired cases. The most
commonly reported Salmonella serotypes were S. Typhimurium (n=90), with 86% of cases
for whom relevant information was available acquiring their infection in WA. Pulsed-field
gel electrophoresis (PFGE) is used in WA for the subtyping of S. Typhimurium (STM) and
the most common PFGE types were type 39 (n=22), PFGE type 3 (n=7) and PFGE type
121 (n=7, see section 4). S. Enteritidis (n=48) was the second most common Salmonella
serotype, which was mostly (94%) acquired overseas, in particular following travel to
Indonesia (76% of cases). The third most common Salmonella serotypes were S. Infantis
(n=17), which was the subject of an ongoing cluster investigation (see section 4); and S.
5
Paratyphi B var Java (n=17). Of the 11 S. Paratyphi B var Java cases with known travel
history, 9 (81%) acquired their infection overseas.
Table 1. Enteric disease notifications for the 2nd quarter of 2013, and comparison to
the mean number for the 2nd quarter for the years 2008 to 2012
Pathogen
Campylobacter
Salmonella
Cryptosporidium
Rotavirus
2013 2nd
Quarter
361
328
125
58
Number of Notifications
Range for
2nd
Quarters
Mean of 2nd
from 2008 to Quarters from
2012
2008 to 2012
338-631
454
175-331
256
26-108
52
51-110
87
2nd Quarter %
Change*
-21%
28%
140%
-34%
*Percentage change in the number of notifications in the current quarter compared to the historical five-year mean for the
same quarter. Positive values indicate an increase when compared to the historical five-year mean of the same quarter.
Negative values indicate a decrease when compared to the historical five-year mean of the same quarter.
The number of Cryptosporidium notifications (n=125) for this quarter represented a
140% increase on the mean number for the previous five years (n=52). Historically,
Cryptosporidium notifications follow a seasonal pattern, with the highest number of
notifications seen in the first quarter of the year followed by a marked decrease in the
second quarter. However, in 2013 Cryptosporidium notifications did not follow this trend,
with only a modest decrease compared to the first quarter. The North Metropolitan region
of Perth accounted for the highest proportion of cases (38%). Amongst cases for whom
relevant information was available, 22% of cases were thought to have acquired their
infection overseas and 77% to have acquired it in WA.
The number of rotavirus notifications (n=58) was 34% lower than the mean for the
previous five years for this quarter (n=87). This decrease is thought to be at least partially
due to changes in laboratory practices, with specimens positive by antigen tests now
requiring confirmation by nucleic acid testing.
In addition, during the second quarter of 2013 enteric disease notifications included:

Shigella: 9 cases compared to the five year mean for this quarter of 29 cases. This
decrease was mainly due to a fall in the number of notifications in Aboriginal
people, from a five year mean of 15 cases to two cases for this quarter in 2013.
6

Hepatitis A: six cases (four male, two female) ranging in age from 12 to 55 years.
Four cases acquired their infection overseas (United Kingdom, Ethiopia, Iraq and
Fiji), while two cases were secondary transmissions from an overseas-acquired
case (see section 3).

Paratyphoid fever: four cases (three female, one male) ranging in age from 20-43
years. All acquired their infection overseas, with travel to Pakistan (n=1), India (n=1)
and Indonesia (n=2).

Typhoid fever: one female case aged 2 years. Case acquired the infection in India.

Listeria monocytogenes infection: two cases (one male, one female) aged 91 and
93 years, respectively. These cases were part of an outbreak which included one
case from the previous quarter (see section 3).

Vibrio parahaemolyticus infection: four cases (three male, one female) ranging in
age from 23-63 years. Cases acquired their infection in Thailand (n=2) and
Indonesia (n=2).

Shiga toxin producing E. coli infection: one male case aged 9 years. Specimen
culture positive for E. coli O157. Case had contact with sheep and lambs and their
manure on a farm during the incubation period.
There were no notifications for hepatitis E, botulism, cholera or Yersinia in this quarter.
3. Foodborne and suspected foodborne disease
outbreaks
There were three foodborne disease outbreaks investigated in this quarter.
3.1 Meal delivery service, Listeria (outbreak code: 021-2013-001)
Three cases of Listeria monocytogenes infection in elderly people (aged 91-93 years), with
onset dates of 7/2/2013, 24/4/2013 and 21/5/2013. All cases purchased frozen meals from
the same home delivery service. Purchase records for the three cases were not available,
so it is unknown what meals were in common. Two cases had the same Listeria PFGE
type, which was indistinguishable from that of a 2011 food isolate from the implicated
company. The third case had a different PFGE type. A roast beef meal sample collected
during an assessment of the food business on 27/5/13 was positive for Listeria
7
monocytogenes of a different PFGE type to that of the cases. No significant food safety
issues were identified during the assessment.
3.2. Lunch bar outbreak, Salmonella Infantis (outbreak code: 042-2013-003)
There were six cases of Salmonella Infantis (confirmed cases) with onsets of illness from
26/2/2013 to 3/5/2013 who prior to illness had eaten a range of foods (Asian stir fry and
sandwiches) purchased from the same lunch bar. There was an additional S. Infantis case
(probable case) who had eaten at the lunch bar, albeit at least three weeks prior to illness.
Six food samples collected during an environmental investigation of the food business on
the 22/4/13 (egg salad, Thai beef salad and seafood salad) and 21/5/13 (fried rice,
coleslaw, rice and salad) were positive for S. Infantis. Due to poor compliance with the WA
Food Act, 2008, the lunch bar was closed until the food business improved food and hand
hygiene standards. There was also an increase in S. Infantis cases with no link to the
lunch bar and these cases had frequently eaten eggs (see section 4.3). The eggs used at
the lunch bar were not produced in WA. The isolates from all confirmed cases and food
samples had an indistinguishable PFGE pattern, while the probable case had a different
PFGE pattern. Stool samples from staff were negative for S. Infantis. The source of S.
Infantis contamination was not identified.
3.3. Kava session, Hepatitis A (outbreak code: 019-2013-001)
Four cases of hepatitis A were notified in the Goldfields region in a short period, which was
unusual given the last notification from this region was in 2006. Investigation by the
Goldfields PHU determined the index case travelled to Fiji during the incubation period,
with onset of illness 26/5/13. While infectious, the index case prepared kava for a group of
friends, two of whom subsequently developed hepatitis A, with onset dates of 20/6/13 and
22/6/13. No other common exposure was identified. The child of one of the cases also
developed hepatitis A, with onset of illness 22/7/13, despite receiving a hepatitis A
vaccination on 5/7/13. All four cases were typed at the Victorian Infectious Diseases
Reference Laboratory as hepatitis A genotype IA, with 100% homology.
8
Table 2. Foodborne outbreaks, 2nd quarter 2013
Suspected
mode of
transmission
foodborne
foodborne
foodborne
Outbreak
number
042-2013003
021-2013001
019-2013001
Month of outbreak
Apr
May
May
Where food
prepared
takeaway
commercial
manufactured
food
private
residence
Where food
eaten
community
private
residence
private
residence
Agent
responsible
Number Hospit Died Evidence Responsible
affected alised
vehicles
Salmonella
Infantis
6
1
0
D, M
multiple
contaminated
foods
identified
Listeria
monocytogenes
3
3
0
D
unknown
Hepatitis A
4
4
0
D
kava
M=microbiological evidence. D=Descriptive evidence obtained from interviewing cases.
4. Cluster investigations
There were three cluster investigations during the second quarter of 2013, including one
ongoing investigation from the first quarter.
4.1. Salmonella Typhimurium PFGE 121
There were seven cases of STM PFGE 121 (phage type 22) with onsets from April to
June, compared to the five year average of one case. Six of the seven cases were aged 3
years or younger. Of the six young children, five cases had dogs that were fed raw
kangaroo meat and the seventh case was a 53 year old male who had contact with a dog
that was fed raw chicken necks and beef bones. Four retail samples of kangaroo meat for
dogs and cats were sampled, all were positive for a variety of Salmonella serotypes,
including S. Muenchen (in one sample), S. Orion (in two samples), S. Infantis (in one
sample), S. Typhimurium (in one sample) and S. Newport (in one sample).
4.2. Salmonella Potsdam
Seven cases were notified between 9/4/13 and 9/5/13. Cases ranged in age from 2-57
years, with two male and five female cases. Five cases were from the Perth metropolitan
area, with one case each from the Southwest and Kimberley regions. Four cases were
interviewed, with no common venues or exposures identified.
4.3. Salmonella Infantis
There was an ongoing cluster investigation of S. Infantis from March to June 2013. Within
this period, seven cases (one in 1st quarter, six in 2nd quarter) were part of an identified
outbreak associated with a lunch bar (see section 3.2). Of the remaining unattributed
9
cases, 12 were notified in the 1st quarter (see Foodborne Disease Surveillance and
Outbreak Investigations in Western Australia, First Quarter 2013) and 16 were notified in
the 2nd quarter. Descriptive analysis was conducted on the 28 cases and details include:

36% male and 64% female, median age 31 years (range <1 to 77 years) with 68%
resident in the Perth metropolitan area.

There were 11 different PFGE types, including type 3 (n=11), type 2 (n=4), type 4 (n=3)
and type 5 (n=3).

Of the 28 cases, 16 had complete interviews and foods frequently eaten by these
cases included eggs at home (88%), cucumber (75%), pasteurised milk (69%) and
bananas (69%).

Of 11 cases with PFGE type 3, eight had complete interviews and foods frequently
eaten included eggs at home (88%), beef (75%), canned fish (75%) and cucumber
(75%).

From 24/2/2013 to 6/6/2013 there were 26 non-human S. Infantis isolations. This
included 11 egg isolates from at least four different WA egg producers and seven of
these isolates had the same PFGE type as human cases (PFGE type 2 [n=4], PFGE
type 4 [n=1], PFGE type 5 [n=2]). The PFGE type 2 was also associated with the lunch
bar outbreak described in section 3.2. Other non-human isolates were from bovine
samples(n=2) but thePFGE types did not match those of the human isolates. There
was also 13 meat meal samples with 10 of these isolates matching chicken and human
isolates (PFGE type 2 [n=1], PFGE type 4 [n=1], PFGE type 5 [n=9]). Meat meal is the
base material that can be processed into chicken feed.

Environmental investigations determined that the all egg producers mentioned above
obtained their chickens from the same hatchery.

The descriptive epidemiological and microbiological evidence, although not definitive,
indicates that eggs contaminated with S. Infantis were the likely source of many of the
human cases. As meat meal samples were positive for S. Infantis it is also possible
that egg-laying flocks may have been infected by the meat meal. It was difficult to link
human cases directly with positive egg producers due to poor case recall of the egg
brand eaten.
10
Table 3. Cluster investigations in WA, 2nd quarter 2013
Month
Setting
Exposed
April
community
May
community
May
community
Agent
responsible
Salmonella
Infantis
Number
affected
Hospitalised
Deaths
16
5
0
7
0
0
7
1
0
S. Typhimurium
PFGE 121
Salmonella
Potsdam
5. Non-foodborne disease outbreaks and outbreaks
with an unknown mode of transmission
There were 21 outbreaks of enteric disease in this quarter that appeared to be nonfoodborne (Table 4). Eighteen outbreaks were ascribed to person-to-person transmission
and three outbreaks had an unknown mode of transmission.
5.1. Person-to-person outbreaks
In the 18 non-foodborne outbreaks that were suspected to be due to person-to-person
transmission, 16 outbreaks (89%) occurred in RCFs, one was in a child-care centre (5%)
and one was at a protestor camp (5%). The causative agent for 12 (67%) outbreaks was
confirmed as norovirus. The remaining 6 (33%) outbreaks had an unknown aetiology, as
specimens were either not collected (n=3) or were negative for common viral and bacterial
pathogens (n=3).
A total of 433 people were affected in these 18 outbreaks, with seven hospitalisations and
one associated death identified. The number of person-to-person outbreaks for this
quarter was 25% lower than the five-year mean for the second quarter (n=24).
5.2. Outbreaks with unknown mode of transmission
There were three outbreaks in this quarter with an undetermined mode of transmission,
with two in RCFs and one in a mental health facility. A total of 17 people were affected in
the three outbreaks, with no reported hospitalisations or deaths.
In the two RCF outbreaks, the most common symptom was diarrhoea, while vomiting was
reported infrequently, which is not typical of norovirus outbreaks in RCF settings. One
11
outbreak with 10 ill persons had two specimens tested, both of which were negative for
common bacterial and viral pathogens. The second outbreak in a RCF with unknown
mode of transmission had four ill residents, with diarrhoea only and no specimens were
tested.
In the mental health facility outbreak, two patients and one staff-member had diarrhoea.
The two specimens collected were negative for common bacterial and viral pathogens.
Table 4. Outbreaks of non-foodborne transmission in WA, 2nd quarter 2013
OUTBREAKS WITH NON-FOODBORNE TRANSMISSION
Mode of
transmission
Setting Exposed
Aged Care
Person to person Aged Care Total
Child Care Centre
Camp
Agent
responsible
Norovirus
Unknown
Unknown
Unknown
Sub Total
Unknown
Aged Care
Mental Health
Facility
Sub Total
Grand Total
Number of
outbreaks
12
4
Number of
cases
404
22
Number of
cases
hospitalised
5
2
16
1
1
426
3
4
7
0
Unknown
1
0
0
1
Number of
cases died
1
0
18
433
7
1
Unknown
2
14
0
0
Unknown
1
3
0
0
3
17
0
0
21
450
7
1
1 Deaths temporally associated with gastroenteritis, but contribution to death not specified
6. Site activities
During the second quarter of 2013, the following activities were conducted at the WA
OzFoodNet site:

Ongoing surveillance of foodborne disease in WA.

Investigation of three foodborne outbreaks.

Investigation and monitoring of 18 non-foodborne gastroenteritis outbreaks and
three outbreaks of unknown transmission.

Three Salmonella clusters were investigated.

Interviewing Salmonella Enteritidis cases regarding travel status and interviewing
locally acquired cases to help determine risk factors for illness.

Ongoing monthly meetings with the WA Health Food Unit to improve coordination of
foodborne disease surveillance and investigation in WA.
12

Ongoing quarterly meeting with the Food Unit and Department of Food and
Agriculture to enhance surveillance of non-human and human enteric disease.

Working with the Food Unit to update enteric disease fact sheets.

Membership of national OzFoodNet working groups on:
o Reviewing the Outbreak Register
o S. Typhimurium and monophasic Salmonella phage type 193 infections (joint
lead investigators with SA OzFoodNet site)
o Egg outbreaks
o National enhanced Listeria surveillance system
o National descriptive study of S. Enteritidis

Participation in monthly national OzFoodNet teleconferences.

Attendance at the National OzFoodNet Face-to-Face meeting in Hobart in June
2013.
o Presented session on the National enhanced Listeria surveillance system

Commenced analysis of data from the WA Cryptosporidium case-control study.

Ongoing collaboration with Murdoch University on the epidemiology and molecular
typing of Cryptosporidium in WA.
7. References
1
2
Hall G, Kirk MD, Becker N, Gregory JE, Unicomb L, Millard G, et al. Estimating
foodborne gastroenteritis, Australia. Emerg Infect Dis 2005;11(8):1257-1264.
OzFoodNet Working Group. A health network to enhance the surveillance of
foodborne diseases in Australia. Department of Health and Ageing 2013.
www.ozfoodnet.gov.au/internet/ozfoodnet/publishing.nsf/Content/Home-1
[14/03/2012]
13
This document can be made
available in alternative formats on
request for a person with a disability.
© Department of Health 2013