A bulletin for the Australian Food Industry November 1999
Contents: Genetically modified foods | International Food Safety Conference | Foodborne outbreaks in Australia | Salmonella in unpasteurised orange juice - US | Preliminary treatment of fruit for fresh juice | High pressure processing of foods | Listeriosis from fruit salad | Cold Chain Guidelines
Foodborne outbreaks in Australia: lessons to be learned
To update the findings of a summary of foodborne outbreaks from 1980 to 1995, state health departments were asked to document all outbreaks investigated since that time and a comprehensive literature search was conducted. To date, 71 outbreaks, comprising over 4300 cases have been reported from NSW, QLD, VIC, SA and NT. The most frequent causes were attributable to Salmonella (30), ciguatera (8), Clostridium perfringens (5), Campylobacter (4), and Listeria monocytogenes (4). Other less frequently implicated agents included hepatitis A, Norwalk virus, scombroid, Shigella, Salmonella typhi, toxoplasmosis, and enterohaemorrhagic E. coli.
Of the 13 fatalities included in the reports, 6 were due to Listeria monocytogenes, 6 were due to Salmonella species, and 1 was due to Clostridium perfringens. Ten of the 13 (70%) deaths were among persons exposed to the implicated foods in hospital or nursing home settings.
Several themes are already arising from the data. There is increasing evidence of the risks associated with minimally processed foods such as juices, fruit salad, and possibly garlic. Several outbreaks occurred in settings that had accredited HACCP plans. Some of these outbreaks could have been prevented if the food safety program had included a check on the quality of the supply chain.
Commercial catering was responsible for at least two outbreaks when the food handling facilities on site were incapable of maintaining appropriate storage and cooking temperatures. The finding that most of the deaths associated with these reports occurred among patients in hospitals and nursing homes is consistent with studies overseas and highlights the need for strategies to protect these vulnerable consumers. The more frequent use of case control study methodology and sophisticated microbiological sub-typing methods is assisting public health agencies to identify the cause of more outbreaks which enhances our understanding of foodborne disease epidemiology.
The survey data has many limitations due to the incomplete nature of the reports and the multiple barriers to the detection, reporting, and investigation of outbreaks. Prospective centralised reporting of outbreaks in a standardised format would greatly improve our understanding of foodborne disease and help inform Australian HACCP food safety programs.
The sentinel surveillance site for foodborne illness in the Hunter has only preliminary data available at present. The preliminary analysis of the case- control study of 69 adult cases of sporadic campylobacteriosis has found an association between illness and take- away food consumption and with the consumption of chicken in restaurants. Further foodborne disease incidence and case- control study information from the site should be available early next year. In the future, a nationwide network of sentinel programs could provide timely information on the incidence, burden and causes of foodborne disease.
For further information contact:
Dr Craig Dalton, Director,
Hunter Public Health Unit.
Telephone: 02 49246 477
Email: cdalt@doh.health.nsw.gov.au
Food Science Australia
PO Box 52, North Ryde 1670. Tel +61 2 9490 8397 Fax +61 2 9490 8499
Email enquiries@csiro.au