Enhancing Foodborne Disease Surveillance Across Australia Quarterly Report July

Enhancing Foodborne Disease Surveillance Across Australia Quarterly Report July - September 2003 (excerpt)

Communicable Diseases Intelligence, Volume 27, Issue number 4 - December 2003

OzFoodNet, Western Australia December 2003,  Minda Sarna, Communicable Disease Control Branch, Department of Health, Grace Vaughan House, 227 Stubbs Terrace, Shenton Park WA 6008, Tel: 08 9388 4858, Fax: 08 9388 4877, Email: minda.sarna@health.wa.gov.au

 

Note: This is an excerpt (pages 13-15) containing sprout related information. 

Cluster Investigations

A cluster investigation was also undertaken to investigate the increase in S. Oranienburg notifications. Seven cases were notified between 8 August and 1 September, a significant event, as usually in WA between 6 -12 cases are reported every year, with about 50% of cases reported from the Kimberley and Pilbara regions. The cases ranged in age from 20 - 80 years.

Five cases were over the age of 70. They were interviewed between 14 August and 17 September 2003. Four of the cases resided in the metropolitan area, two from the far South and one case came from the Southwest region.

Hypothesis-generating interviews were conducted with all seven cases using the Victorian Salmonella questionnaire with the assistance of local government Environmental Health Officers. Information collected included an illness history, prior contact with a case, travel history, a three-day food history, and specific high-risk foods for Salmonella. Shopping venues and brands of foods were also recorded.

The investigation was complicated by unreliable food histories from two elderly people who had poor recall of food consumption in the week prior to onset of illness. Another two cases reported onset times greater than a month before interview. Consumption of commercially bought products such as milk, cheeses and ice cream was common to some cases. No highrisk candidate from eggs, meats, dressings or sauces common to all cases was identified. Three cases reported consumption at restaurants or takeaways, but again there was no commonality in the venue or food items eaten.

S. Oranienburg has previously been isolated in Australia from a variety of meats, such as beef, pork, goat, poultry and kangaroo meat, as well as other food products such as malting barley, milk powder, salad vegetables and herbal tea (NEPSS Non-human Annual Reports 2002, 2001 and 2000).In 2001, it was also isolated from imported helva. It was also isolated from goat and meat meal, and alfalfa and radish sprouts earlier this year in WA (Ms. Joan Powling, MDU, personal communication), although the latter was not reported to the Department of Health in WA.

Prevention Measures

In addition to routine and enhanced surveillance activities, this quarter's activities included the investigation of three gastrointestinal disease outbreaks and one cluster investigation. Two of these outbreaks were associated with aged care facilities, one of confirmed foodborne transmission and one confirmed person to person transmission. In the first outbreak, the Department of Health made several recommendations to the main caterers as well as the nursing home kitchen staff to avoid a similar incident occurring again. These included:

  • The introduction of an effective HACCP-based Food Safety Program as soon as possible, with guidance from the Department in its development.

  • The introduction of Standard Operating Procedures (SOP) to address the high risk/hazard operation of bulk food preparation

  • The introduction of rigorous time and temperature monitoring system for all food production, from preparation through to delivery and service.

In the second outbreak, infection control measures at the facility were reviewed by Department of Health staff in consultation with the Director of Nursing at the facility. The third outbreak occurred at an indoor kid's play-centre. These facilities are a relatively new phenomenon in the last five years and there are currently no guidelines covering the buildings and the volume or nature of traffic they cater for. They are not public buildings, often being converted factory warehouses, and differ from child-care centres in a number of ways, although similar protocols for the cleaning and disinfection of equipment and toys apply. For those facilities that also provide catering, food safety concerns are managed adequately through local government inspections and audits, and as part of their licensing process.

The cluster investigation into the increase in the number of S. Oranienburg notifications was hampered by the lack of good information collected from some of the cases. Several of the cases were elderly and did not recall well their food consumption. Two other cases had had prolonged illness and reported an onset time well before notification and interview.

Furthermore, information was only collected on items commonly associated with Salmonella infections and did not focus on unusual or exotic food items.At the time of interview, the information about Salmonellaisolated from sprouts in May 2003 in WA was not known, and specific questions about sprouts and salad lettuces were not posed. This illustrates well the difficulty in conducting these investigations when there may be potential contamination of a product not conventionally associated with sources of Salmonella.

Food surveillance is thus vital in these cluster investigations. Salmonella isolations from foods are notifiable in WA but not all private companies comply with this requirement.

Salmonella was isolated from four specimens in May 2003, but the Department of Health was only notified of one. Furthermore, most companies are only interested in knowing if microbial contamination exists and do not further speciate any positive Salmonella isolates because of the added expense of serotyping and phage typing, making it difficult to correlate food isolates to clinical isolates contemporaneously.

Acknowledgments

Acknowledgment is given to the following people for their kind assistance in preparation of this report: Mr. Brian MacKenzie, the Western Australian Centre for Pathology and Medical Research; Ms.Joan Powling, the Microbiological Diagnostic Unit and the National Enteric Pathogens Surveillance Scheme; Mr. Walter Arrow, Ms. Megan Scully, Ms. Amy Tran, Mr. Llew Withers, Department of Health, Government of Western Australia.

References

NEPSS Non-human Annual Report, 2002.

NEPSS Non-human Annual Report, 2001.

NEPSS Non-human Annual Report, 2000.