OzFoodNet WA 2Q 2007 Report

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OzFoodNet WA 2Q 2007 Report Powered By Docstoc
					OzFoodNet—Enhancing Foodborne
Disease Surveillance Across
Australia
Quarterly Report
April to June 2007
Western Australia
________________________________

Robyn Gibbs, Nevada Pingault and Mary Barker

June 2007




                            Communicable Disease Control
                            Directorate
                            Health Protection Group
                            Health System Support Division
                            Department of Health, Western
                            Australia

                            PO Box 8172
                            Perth Business Centre WA 6849

                            Tel: 08 9388 4811
                            Fax: 08 9388 4877
                                                  Email:
                            Robyn.Gibbs@health.wa.gov.au



                   1
Table of Contents
Table of Contents                                                               1
Summary and Recommendations                                                     2
Activity During The Quarter                                                     3
Incidence of Foodborne and Gastrointestinal Disease Outbreaks                   4
Figure 1. Number of non-foodborne gastroenteritis outbreaks reported to WA
DOH per month, 2004 to 2007                                                     5
Cluster Investigations                                                          6
Cluster Investigations                                                          6
References                                                                      6
Acknowledgements                                                                6
Table 1. Gastrointestinal Disease Investigations, April to June 2007, Western
Australia                                                                       7




                                       1
Summary and Recommendations
This report describes OzFoodNet surveillance activities conducted in Western
Australia between April and June 2007.

One suspected outbreak of foodborne illness was investigated. It was found that 26
of 184 employees working in a company office had gastroenteritis in early June. A
case control study showed that illness was strongly associated with eating at the staff
cafe (OR 38, 95% CI 4.34 - 855.6, p=0.0000087). No association with a particular
food was found. Faecal samples were positive for norovirus. Café staff did not report
any illness and did not provide faecal specimens. The source of the infection was
not found.

The number of non-foodborne outbreaks in this quarter was higher than for any
quarter from the three previous years. There were 54 non foodborne outbreaks in
this quarter affecting 1638 people.     For 72% of these outbreaks norovirus was
confirmed as the causative agent.




                                          2
Activity During The Quarter
During the second quarter of 2007, the following activities were conducted at the
West Australian OzFoodNet site:

•      Ongoing surveillance of foodborne disease in Western Australia.

•      Intensive investigation of one case of paratyphoid fever and one case of
Vibrio parahaemolyticus infection.

•      One investigation of a suspected foodborne disease outbreak caused by
norovirus.

•      Investigation of 54 non-foodborne gastroenteritis outbreaks, 36 of which
occurred in aged care facilities, 16 in hospitals and two at minesite camps.




                                           3
Incidence of Foodborne and Gastrointestinal
Disease Outbreaks
There was one suspected outbreak of foodborne disease in this quarter. In early
June a company reported a suspected outbreak of gastroenteritis to the Department
of Health. The suspected outbreak was at one of the offices of this company.
Interviews confirmed that 26 out of 184 staff who worked at this office were ill with
gastroenteritis on 7 and 8 June (Attack Rate 14%). A case control study was
conducted with 26 cases and 36 controls interviewed. Illness was strongly
associated with eating at the staff cafe in the 48 hours prior to onset of symptoms
(OR 38, 95% CI 4.34 - 856, p=0.0000087). No association with a particular food was
found. Faecal specimens from affected employees were collected with 3/3 positive
for norovirus. Café staff did not report any illness and did not provide faecal
specimens. An environmental health inspection of the premises did not identify any
deficiencies in food handling practices.

There were 54 outbreaks of disease in this quarter that appeared to be non-
foodborne, 36 of which occurred in aged care facilities, 16 in hospitals and two at
minesite camps. The causative agent for 39 (72%) of this quarter’s outbreaks was
confirmed as norovirus, and for the remainder of the outbreaks the causative agent
was unknown. There were a total of 1638 people affected by these outbreaks.
The total number of non foodborne outbreaks reported in this quarter was higher than
for any previous quarter for the years 2004 to 2007. The average number of reported
outbreaks per quarter from previous years was 13 and the highest number per
quarter was 38. Figure 1 shows that the number of outbreaks reported in June, that
is 28, was higher than reported in any month of the previous three years. This figure
shows that there have been large increases in the number of reported outbreaks in
previous years, in either the spring or autumn. The reason for these increases in
outbreaks is unknown, although they may have been caused by the arrival in WA of a
novel norovirus genotype. A previous publication showed that marked increases in
norovirus activity in NSW were likely to be caused by a novel and more virulent GII.4
norovirus strain, which also caused outbreaks in The Netherlands, Taiwan and Japan
(Bell et al 2006). PathWest Laboratory Medicine have commenced a study to
examine genotypic differences between norovirus isolates in WA.




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                   30




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                   20
No. of outbreaks




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                          2004              2004                  2004               2004           2005              2005                  2005           2005                  2006               2006               2006           2006                  2007               2007
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Figure 1. Number of non-foodborne gastroenteritis outbreaks reported to WA
                                                                                            DOH per month, 2004 to 2007




                                                                                                                                             5
Cluster Investigations
Nothing to report.




References
Bell, RA, Tu, ETV, McIver, CJ, Rawlinson, WD and White, PA 2006, ‘Emergence of a
new norovirus genotype II.4 variant associated with global outbreaks of
gastroenteritis’, Journal of Clinical Microbiology, vol. 44, no. 2, pp. 327-333




Acknowledgements
Acknowledgement is given to the following people for their gracious assistance with
the activities described in this report: Mr. Brian MacKenzie and Ms. Lyn O’Reilly from
PathWest Laboratory Medicine WA; Dr Donna Mak, Ms Beth Lord, Mr Barry Combs,
Mr Bill Calder and Ms Sharna Walsh from Department of Health, Government of
Western Australia; Dr Lissie Swingler, Master of Applied Epidemiology registrar,
Australian National University; Ms Maria Hatgivasiliou, Town of Bassendean




                                            6
Table 1. Gastrointestinal Disease Investigations, April to June 2007, Western Australia

     Month
  Investigation                          Suspected Mode     Number       Number               Agent
  Commenced      Setting Exposed         of Transmission    Affected   Hospitalised         Responsible   Epidemiolgical Study
 Non-Foodborne Outbreaks
 April              hospital             Person-to-person         26        NA            Norovirus                D
 April              hospital             Person-to-person         63        NA            Norovirus                D
 April              aged care facility   Person-to-person         16         0            Norovirus                N
 April              aged care facility   Person-to-person         26         3            unknown                  D
 April              aged care facility   Person-to-person         42         2            Norovirus                D
 April              aged care facility   Person-to-person         41         3            Norovirus                D
 April              aged care facility   Person-to-person          5         0            unknown                  D
 April              aged care facility   Person-to-person          5         0            unknown                  D
 April              aged care facility   Person-to-person         36         0            Norovirus                D
 April              aged care facility   Person-to-person         11         0            unknown                  D
 April              aged care facility   Person-to-person          5         0            unknown                  D
 April              aged care facility   Person-to-person          4         0            unknown                  D
 April              aged care facility   Person-to-person         16         0            unknown                  D
 April              aged care facility   Person-to-person         21         0            Norovirus                D
 April              hospital             Person-to-person         12        NA            unknown                  D
 May                hospital             Person-to-person         35        NA            Norovirus                D
 May                hospital             Person-to-person         38        NA            Norovirus                N
 May                aged care facility   Person-to-person         13         1            Norovirus                D
 May                aged care facility   Person-to-person         37         0            Norovirus                D
 May                hospital             Person-to-person         14        NA            Norovirus                D
 May                hospital             Person-to-person         21        NA            Norovirus                D



                                                                   7
May    hospital             Person-to-person   12    1   Norovirus   D
May    aged care facility   Person-to-person   29    0   unknown     D
May    aged care facility   Person-to-person   83    0   Norovirus   D
May    aged care facility   Person-to-person   54    3   Norovirus   D
May    aged care facility   Person-to-person   38    4   Norovirus   D
June   hospital             Person-to-person   19   NA   Norovirus   D
June   hospital             Person-to-person   33   NA   Norovirus   D
June   aged care facility   Person-to-person    7    0   unknown     D
June   aged care facility   Person-to-person   79    0   Norovirus   D
June   aged care facility   Person-to-person   18    1   Norovirus   D
June   aged care facility   Person-to-person   38    4   Norovirus   D
June   aged care facility   Person-to-person   21    4   Norovirus   D
June   hospital             Person-to-person    8   NA   Norovirus   D
June   aged care facility   Person-to-person    8    0   unknown     D
June   hospital             Person-to-person   29   NA   Norovirus   N
June   aged care facility   Person-to-person   27    0   Norovirus   D
June   hospital             Person-to-person   26   NA   Norovirus   D
June   aged care facility   Person-to-person   14    0   unknown     D
June   aged care facility   Person-to-person   20    0   Norovirus   D
June   aged care facility   Person-to-person   77    3   Norovirus   D
June   aged care facility   Person-to-person   38    0   Norovirus   D
June   aged care facility   Person-to-person   63    3   Norovirus   D
June   hospital             Person-to-person   28   NA   Norovirus   D
June   aged care facility   Person-to-person   47    0   Norovirus   D
June   hospital             Person-to-person    7   NA   Norovirus   N
June   aged care facility   Person-to-person   46    0   Norovirus   D
June   aged care facility   Person-to-person   26    0   Norovirus   D
June   other                Person-to-person   90    0   unknown     D
June   aged care facility   Person-to-person   23    0   Norovirus   D
June   aged care facility   Person-to-person   45    0   Norovirus   D
June   hospital             Person-to-person    5   NA   unknown     N
June   aged care facility   Person-to-person   59    1   Norovirus   D



                                               8
 June                  other                 Person-to-person               34            0           unknown     D
 Total                                                                    1638            33
 Foodborne Outbreaks
 June                  restaurant            Foodborne                       26           2           Norovirus   CCS
 Total                                                                       26           2


Abbreviations: D=descriptive case series; CCS=case control study; N=individual patient data not collected.




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