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Foodborne disease outbreaks across Australia, January-March 2005

OzFoodNet is a national network of epidemiologists working with State and Territory governments and other organisations to investigate foodborne disease in Australia. During 2005, OzFoodNet strengthened surveillance of these very common diseases.

Summer is the most common time of year for foodborne diseases. During the first three months of 2005, OzFoodNet sites reported 31 outbreaks of illness that were due to contaminated food, compared with 24 outbreaks for the same time in the previous year. Salmonella Typhimurium caused seven of these outbreaks, while ciguatoxin was responsible for three outbreaks and Campylobacter for two. Of the remaining outbreaks, one each was caused by Clostridium perfringens, Salmonella Enteritidis 26 var, Salmonella Hessarek, Salmonella Saint-Paul, and suspected histamine poisoning.

In one outbreak in an aged care facility there were multiple serotypes of Salmonella isolated from patients including Chester, Muenchen and Subspecies 3b. Salmonella Subspecies 3b was also isolated from water samples from a rainwater tank at the facility. Tanks may be unsuitable as a source of drinking water for institutions and may be a more common cause of disease than previously recognised. An aetiological agent was not identified for 42 percent (13/31) of the outbreaks.

Outbreaks were associated with meals prepared in restaurants (10), food prepared in private residences (7), aged-care facilities (5) and food prepared by commercial caterers (4). The largest was an outbreak of Salmonella Typhimurium 197 at a Turkish restaurant in Victoria. S. Typhimurium 197 was isolated from dips served at the restaurant. At the same time, New South Wales reported an increase of Salmonella Typhimurium 197 cases among people of Middle Eastern ethnicity, although no connection between the two outbreaks could be made.

There were five outbreaks associated with dishes containing eggs during the first quarter – two of these outbreaks were related to hollandaise sauce prepared in restaurants in different States. These outbreaks highlight the importance of restaurants using pasteurised egg in sauces and desserts. One of the egg associated outbreaks was an outbreak of Salmonella Enteritidis in an aged care facility. Australia does not have Salmonella Enteritidis endemic in egg laying flocks, so it is vital that public health agencies investigate infected patients, as they may represent sentinels for new emerging sources of this pathogen.

This article was contributed by OzFoodNet. For more information see the OzFoodNet reports in the latest issue of Communicable Diseases Intelligence:
http://www.health.gov.au/internet/main/publishing.nsf/Content/cda-pubs-cdi-cdiintro.htm
or contact:
Martyn Kirk, Coordinating Epidemiologist, OzFoodNet,
Tel: +61 2 6289 9010, martyn.kirk@health.gov.au