Foodborne disease surveillance and outbreak investigations in Western Australia, third quarter 2014

OzFoodNet, Communicable Disease Control Directorate

Enhancing foodborne disease surveillance across AustraliaCommunicable Disease Control Directorate

Acknowledgments

Acknowledgement is given to the following people for their assistance with the activities

described in this report: Mr Damien Bradford, 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; Mrs Anna Anagno and other staff from the Food Unit of the

Department of Health, Western Australia; Public Health Nurses from the metropolitan and

regional Population Health Units; and Local Government Environmental Health Officers.

Contributors/Editors

Nevada Pingault, Sarojini Monteiro and Barry Combs

Communicable Disease Control DirectorateDepartment of Health, Western AustraliaPO Box 8172Perth Business CentreWestern Australia 6849

Email: OzfoodnetWA@health.wa.gov.au

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.pmOzFoodNet Department of Health and Ageingwww.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.

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Executive summary During the third quarter 2014, the Western Australian (WA) OzFoodNet team conducted

surveillance of enteric diseases, undertook investigations into outbreaks and was involved

with ongoing enteric disease research projects.

The most common notifiable enteric infections in WA were campylobacteriosis (n=739),

salmonellosis (n=252), rotavirus (n=103) and cryptosporidiosis (n=41). Notifications of

Campylobacter and Cryptosporidium were higher than the five-year third quarter mean,

while rotavirus notifications decreased compared to the third quarter mean.

An investigation was conducted into one foodborne Clostridium perfringens outbreak at an

aged care facility associated with consumption of a soft / vitamised meal. The investigation

into the increase in S. Typhimurium PFGE 0001 cases continued in the third quarter.

OzFoodNet also conducted surveillance of 34 non-foodborne outbreaks. Of these, the

most common mode of transmission was person-to-person (27 outbreaks), with a total of

529 people ill. Norovirus was the main agent responsible for infection (13 outbreaks), and

half of the person-to-person outbreaks were in residential care facilities. There were seven

outbreaks with an unknown mode of transmission, with a total of 93 people ill.

Figure 1 Notification rates of the four most common enteric diseases by quarter from 2009 to 2014, WA

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Table of Contents

Executive summary...........................................................................................................21 Introduction.................................................................................................................52 Incidence of notifiable enteric infections.................................................................6

2.1 Methods..................................................................................................................62.2 Campylobacteriosis.................................................................................................62.3 Salmonellosis..........................................................................................................72.4 Rotavirus infection...................................................................................................82.5 Cryptosporidiosis.....................................................................................................92.6 Other enteric diseases and foodborne illness.........................................................9

3 Foodborne and suspected foodborne disease outbreaks....................................103.1 Clostridium perfringens outbreak at an residential care facility (outbreak code 09/14/BEE).....................................................................................................................10

4. Cluster investigations...............................................................................................114.1. S. Typhimurium PFGE 0001, phage type 9...........................................................11

5. Non-foodborne disease outbreaks and outbreaks with an unknown mode of transmission.....................................................................................................................11

5.1. Person-to-person outbreaks..................................................................................125.2. Outbreaks with unknown mode of transmission....................................................12

6. Site activities.............................................................................................................137. References.................................................................................................................14

List of Tables

Table 1 Number of Campylobacter notifications, 3rd quarter 2014, WA, by region...........................6Table 2 Number of salmonellosis notifications, 3rd quarter 2014, WA, by region..............................7

List of Figures Figure 1 Notification rates of the four most common enteric diseases by quarter from 2009 to 2014, WA.......................................................................................................................................................2

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Notes:

1. All data in this report are provisional and subject to future revision.

2. To help place the data in this report in perspective, comparisons with other reporting periods are provided. As no formal statistical testing has been conducted, some caution should be taken with interpretation.

Copyright to this material is vested in the State of Western Australia unless otherwise indicated. Apart from any fair dealing for the purposes of private study, research, criticism or review, as permitted under the provisions of the Copyright Act 1968, no part may be reproduced or re-used for any purposes whatsoever without written permission of the State of Western Australia.

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1 IntroductionIt has been estimated that there are 5.4 million cases of foodborne illness in Australia

each year at a cost of $1.2 billion per year1. This is likely to be an underestimate of the

total burden of gastrointestinal illness 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 institution infection control.

This report describes enteric disease surveillance and investigations carried out during the

third quarter of 2014 by OzFoodNet WA, other WA Department of Health (WA Health)

agencies and local governments. Most of the data are derived from reports to WA Health

of 16 notifiable 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 Health2. 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 and investigation in 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.

The Food Unit liaises with Local Government (LG) Environmental Health Officers (EHO)

during the investigation of food businesses. The Food Hygiene, Diagnostic and Molecular

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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 infections2.1 MethodsEnteric disease notifications were extracted from the Western Australian Notifiable

Infectious Diseases Database (WANIDD) by optimal date of onset (ODOO) for the time

period 1st July 2009 to 30th September 2014. 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. Rates were calculated using estimated resident

population data for WA from Rates Calculator version 9.5.5 (WA Health, Government of

Western Australia), which is based on 2011 census data. Rates calculated for this report

have not been adjusted for age.

2.2 CampylobacteriosisCampylobacteriosis was the most commonly notified enteric disease in WA during the

third quarter of 2014 (3Q14), with 739 notifications (Table 1) and a rate of 117 per 100

000 population per year. There was a 40% increase in notifications of campylobacteriosis

in the 3Q14 compared with the five year mean. The increase appeared to be due to

sporadic disease, as there were no identified outbreaks due to campylobacteriosis during

the 3Q14. The increase is, in part, thought to be due to the introduction of polymerase

chain reaction (PCR) testing of faecal specimens by one pathology laboratory, which has

greater sensitivity than culture techniques. The place of acquisition of infection was

reported for 61% (n=452) of cases, of which 71% (321 cases) were locally acquired and

28% were acquired overseas (128 cases).

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Table 1 Number of Campylobacter notifications, 3rd quarter 2014, WA, by region

Number of Notifications

2014 3rd QuarterMean of 3rd Quarters

from 2009 to 20133rd Quarter %

Change*Pilbara 8 8.6 -7.0Kimberley 11 11.4 -3.5Midwest 11 10.8 1.9Goldfields 14 9 55.6Wheatbelt 18 17.8 1.1Greath Southern 19 16 18.8Southwest 55 44.8 22.8South Metropolitan 238 175.2 35.8North Metropolitan 365 233.8 56.1Total 739 527.4 40.1

Public Health Unit

*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.

2.3 SalmonellosisSalmonellosis, was the second most commonly notified enteric disease in WA in the

3Q14, with 252 notifications (Table 2) and a rate of 40 per 100 000 population per year.

The number of salmonellosis notifications in the 3Q14 was consistent with the five year

mean (n=255).

Table 2 Number of salmonellosis notifications, 3rd quarter 2014, WA, by region

Number of Notifications

2014 3rd QuarterMean of 3rd Quarters

from 2009 to 20133rd Quarter %

Change*Wheatbelt 2 6.2 -67.7Goldfields 5 4.6 8.7Midwest 5 7.2 -30.6Greath Southern 6 7.2 -16.7Pilbara 10 10 0.0Kimberley 20 14.2 40.8Southwest 25 20.8 20.2South Metropolitan 78 81 -3.7North Metropolitan 101 103 -1.9Total 252 255.2 -1.3

Public Health Unit

*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.

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Place of acquisition of infection was known for 79% (n=199) of cases, of which 53% (106

cases) were locally acquired, 46% were acquired overseas (91 cases) and 1% were

acquired interstate (2 cases).

The most commonly reported Salmonella serotype was S. Typhimurium (STM) (n=63),

and of those cases with information on place of acquisition (86%), 48 cases (89%) were

locally acquired. Pulsed-field gel electrophoresis (PFGE) is used in WA for the subtyping

of STM and the most common PFGE types were type 0001 (n=30) and type 0039 (n=8).

Cases with type 0001 were interviewed as part of an on-going cluster investigation (see

section 4).

Salmonella Enteritidis was the second most common Salmonella serotype (n=51), and of

those cases with information on place of acquisition (96%), most (n=46, 94%) acquired

their infection overseas, primarily after travel to Indonesia (n=36, 78%).

The next most commonly notified Salmonella serotypes were S. Saintpaul (n=15), which

were predominantly acquired in WA (13/15); and S. Paratyphi B var Java (n=14), which

were predominantly acquired overseas (9/14).

2.4 Rotavirus infectionIn the 3Q14 there were 103 notifications (Table 4) of rotavirus infection (16 per 100 000

population per year). There was a 30% decrease in rotavirus notifications in the 3Q14

compared with the mean of the previous two years. This decrease can, in part, be

explained by the community wide outbreak of rotavirus in the Kimberley and Pilbara

regions in the 3Q of 2013 increasing the two year mean.

Table 3 Number of rotavirus notifications, 3rd quarter 2014, WA, by regionNumber of Notifications

2014 3rd QuarterMean of 3rd Quarters from 2012 to 2013**

3rd Quarter % Change*

Goldfields 1 1.5 -33.3Greath Southern 1 2.5 -60.0Midwest 2 2 0.0Wheatbelt 3 0.5 500.0Southwest 4 3 33.3Kimberley 6 26 -76.9Pilbara 15 20 -25.0South Metropolitan 30 44 -31.8North Metropolitan 40 49 -18.4Total 103 148.2 -30.5

Public Health Unit

*Percentage change in the number of notifications in the current quarter compared to the historical two-year mean for the same quarter. Positive values indicate an increase when compared to the historical two-year mean of the same quarter. Negative values indicate a decrease when compared to the historical two-year mean of the same quarter.

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**Rotavirus: comparison to two years (2012-2013) of data only because changes in laboratory testing practice (increased use of more specific PCR over antigen testing) over the period 2009 to 2011 complicate comparison to 5-year data.

2.5 Cryptosporidiosis

In the 3Q14, there were 41 cryptosporidiosis notifications (Table 4) (6 per 100 000

population per year), which was a 40% increase compared to the five year mean. The

increase in notifications was mainly observed in the South Metropolitan and Kimberley

regions, although no outbreaks were reported in these regions. The increase is, in part,

thought to be due to the introduction of PCR testing of faecal specimens by one pathology

laboratory, which has greater sensitivity than microscopy and enzyme immunoassay

techniques. The place of acquisition of infection was reported for 68% of cases (n=28) of

which 75% (21 cases) were locally acquired and 25% were overseas acquired (7 cases).

Table 4 Number of cryptosporidiosis notifications, 3rd quarter 2014, WA, by region

Number of Notifications

2014 3rd QuarterMean of 3rd Quarters

from 2009 to 20133rd Quarter %

Change*Goldfields 0 1.8 -100.0Greath Southern 0 1.2 -100.0Wheatbelt 2 1.6 25.0Midwest 2 0.8 150.0Pilbara 2 1 100.0Southwest 5 5.4 -7.4Kimberley 8 3.6 122.2North Metropolitan 9 7.2 25.0South Metropolitan 13 6.6 97.0Total 41 29.2 40.4

Public Health Unit

*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.

2.6 Other enteric diseases and foodborne illness

During the 3Q14, other enteric disease notifications included:

Shigella infection: There were 13 Shigella notifications in 3Q14 that were culture

positive, which was consistent with the five year mean (n=14). All notifications were

from non-Aboriginal people, and comprised one S. boydii (acquired in Pakistan,

seven S. sonnei (4 overseas acquired) and five S. flexneri cases (3 overseas

acquired).

Hepatitis A infection: Two locally acquired and three overseas acquired hepatitis

A cases were notified in the third quarter. Of the overseas acquired cases, two

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cases (male 41 years, female 31 years) acquired the infection in Indonesia, while

the third case (male 33 years) acquired the infection in South Africa. The locally

acquired cases (female 56 years, male 31 years) did not appear to have any

common exposures.

Yersinia infection: There were 2 Yersinia notifications in 3Q14 that were culture

positive (both female, aged 20 and 33 years). Both isolates were identified as Y.

enterocolitica.

Paratyphoid fever: One case (male, aged 29 years) who acquired their infection in

Indonesia.

Typhoid fever: Two cases (male 25 years, female 59 years) both of whom

acquired their infection in India.

Vibrio parahaemolyticus infection: One locally acquired (female, 79 years) and

three overseas acquired (all male, aged 25-64 years) cases. The overseas acquired

cases reported travel to Indonesia, Philippines and Vietnam.

STEC/HUS: one case of shiga toxin E. coli O157 in a 41 yo Aboriginal female. The

case developed HUS as a result of the STEC infection.

Suspected cyanide poisoning: A 39 yo female ate four teaspoons of ground

apricot kernels mixed in water and immediately afterwards started to vomit and had

seizures. The patient was admitted to hospital and treated in the intensive care unit

for three days and was then discharged. The apricot kernels were purchased online

and remaining kernels tested had high levels of hydrocyanic acid. This product was

recalled (http://www.foodstandards.gov.au/industry/foodrecalls/recalls/Pages/

Apricot-Kernels.aspx).

There were no notifications for botulism, cholera, Listeria monocytogenes or hepatitis E in

this quarter.

3 Foodborne and suspected foodborne disease outbreaks

There was one foodborne disease outbreak investigated in this quarter.

3.1 Residential care facility Clostridium perfringens outbreak (outbreak code 09/14/BEE)

At a residential care facility, 19 residents became ill with gastroenteritis with onsets from

21/9 to 24/9. Of the 19 residents, 14 became ill on the morning of the 24/9/2014 mainly

with diarrhoea. Seven specimens were positive for Clostridium perfringens toxin. Six of the

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specimens were culture positive for C. perfringens, with 5 isolates typed by PFGE and four

isolates had patterns that were indistinguishable. Most ill residents were from the dementia

wing and had a soft, minced or pureed diet. All these diets are processed in a vitamiser.

An environmental investigation identified remains of food in the vitamiser after it

undergone its normal cleaning procedure. The illness among residents was due to C.

perfringens and it is suspected that an unclean vitamiser may have led to contaminated

food.

4. Cluster investigationsThere was one ongoing cluster investigation during the third quarter of 2014.

4.1. S. Typhimurium PFGE 0001, phage type 9

There were 29 cases of PFGE type 0001 notified with illness, with specimen dates

between 9/7/14 and 30/9/14. The cases included 62% males and 48% females, ranged in

age from <1 to 71 years (average 28 years), and most (90%) resided in the Perth

metropolitan area. Chicken meat sampled in September 2014 was also positive for PFGE

type 0001. Of the 29 cases, 24 were interviewed leading to the hypothesis that the

consumption of free range eggs or chicken meat was the cause of illness. Investigation is

ongoing.

5. Non-foodborne disease outbreaks and outbreaks with an unknown mode of transmission

There were 34 outbreaks of enteric disease in this quarter that appeared to be non-foodborne (see Table 5). Of these, 27 outbreaks were ascribed to person-to-person transmission and seven had an unknown mode of transmission.

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Table 5 Outbreaks with non-foodborne transmission, 3rd Quarter 2014, WA

Mode of transmission

Setting Exposed Agent responsible

Number of outbreaks

Number of cases

Number hospitalised

1 Number died

Person to person Aged care Norovirus 8 164 2 0

Aged care

Norovirus and

Rotavirus 1 50 0 0Aged care Rotavirus 1 6 0 0Aged care Unknown 4 38 1 1

Aged care total 14 258 3 1

Child care Norovirus and Rotavirus

1 32 0 0

Unknown 7 70 0 0

Child care total 8 102 0 0

Hospital Norovirus 1 11 0 0Cruise Norovirus 1 114 0 0

Insitution Norovirus 3 44 0 0

Total 27 529 3 1

Unknown Aged care Unknown 7 93 0 0

Grand total 34 622 3 1© WA Department of Health 2014

Outbreaks with non-foodborne transmission

1 Deaths temporally associated with gastroenteritis, but contribution to death not specified

5.1. Person-to-person outbreaks

In the 27 non-foodborne outbreaks that were suspected to be due to person-to-person transmission, 14 outbreaks (52%) occurred in RCFs, 8 were in child care centres (30%), three were in institutions (11%) and one each occurred in a hospital and on a cruise ship. The causative agent for 13 (48%) outbreaks was confirmed as norovirus, two outbreaks were caused by a combination of norovirus and rotavirus, and rotavirus caused one outbreak. The remaining 11 (41%) outbreaks had unknown aetiology, as specimens were either not collected (n=9) or were negative for common viral and bacterial pathogens (n=2).

A total of 529 people were affected in these 27 outbreaks, with three hospitalisations and one associated death. The number of person-to-person outbreaks in the 3Q14 was consistent with the third quarter mean (n=27.8).

5.2. Outbreaks with unknown mode of transmissionThere were seven outbreaks in this quarter with an undetermined mode of transmission,

all in RCFs. A total of 93 people were affected in the seven outbreaks, with no reported

hospitalisations or deaths. The number of unknown outbreaks in the 3Q14 was increased

compared to the third quarter mean (n=4).

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The most common symptom reported in these outbreaks was diarrhoea, while vomiting

was reported infrequently, which is not typical of norovirus outbreaks in RCF settings.

Stool specimens were collected and tested for four of these outbreaks, but all were

negative for common bacterial and viral pathogens.

6. Site activitiesDuring the third quarter of 2014, the following activities were conducted at the WA OzFoodNet site:

Ongoing surveillance of foodborne disease in WA. Monitoring culture-independent nucleic acid amplification diagnostic testing in

private laboratories and impact on notification rates. Investigation of one foodborne outbreak. Investigation and monitoring of 27 non-foodborne gastroenteritis outbreaks and 7

outbreaks of unknown mode of transmission. One cluster of Salmonella infection continued to be investigated. Responded to national OzFoodNet enteric disease surveillance requests. Attendance at the OzFoodNet face-to-face meeting in Sydney in July and presented

final report on national OzFoodNet strategic plan. Performed data analysis on egg related outbreaks as part of national working

group. Assisted in preparation of document outlining OzFoodNet’s requirements for enteric

surveillance as part of national working group. Interviewing Salmonella Enteritidis cases regarding travel status and attempting to

identify risk factors in locally acquired cases. Ongoing monthly meetings with the WA Health Food Unit to improve coordination of

foodborne disease surveillance and investigation in WA. Continuing to work with PathWest on the introduction in WA of MLVA typing of S.

Typhimurium isolates and PCR testing of bloody stools for STEC. Presented lectures and practical to masters level students on foodborne disease. Membership of OzFoodNet working groups on:

o National STEC surveillance.o Outbreak registero Foodborne disease tool kit

Membership of national working groups on the: o Review of the Series of National Guidelines for Hepatitis A. o Rotavirus Surveillance.

Participation in monthly national OzFoodNet teleconferences.

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7. References1 Hall G, Kirk MD, Becker N, Gregory JE, Unicomb L, Millard G, et al. Estimating

foodborne gastroenteritis, Australia. Emerg Infect Dis 2005;11(8):1257-1264.2 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].

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