Foodborne disease causes an estimated 4.1 million cases of illness in Australia each year and is responsible for causing many significant common source outbreaks. We analyzed 18 years of foodborne outbreak data collected in New South Wales (NSW), and classified the likely pathogen type responsible for outbreaks of unknown etiology, to track broad trends over time. A total of 869 outbreaks were reported in NSW from 2000 to 2017. The majority (53%) of outbreaks did not have a pathogen identified and underwent pathogen type categorization based on the epidemiology of the outbreak. The proportion of outbreaks due to toxin producing bacteria decreased over time, whereas the proportion of outbreaks due to other bacterial pathogens increased. The proportion of outbreaks due to viral gastroenteritis pathogens had no overall changing trend over time. Bacterial outbreaks had significantly more identified cases and had more hospitalizations than other pathogen type causes. Other features associated with high case numbers, hospitalizations, and deaths in foodborne outbreaks included being due to food contaminated in primary production, involving consumption of raw products, and having evidence of poor sanitation in the food preparation areas. Eggs were the most commonly determined pathogen food source, occurring in 12% of outbreaks; however, most outbreak investigations (77%) did not have a pathogen food source identified. This analysis demonstrates a changing landscape of foodborne outbreaks over time. Increases in outbreaks due to bacterial and viral pathogens coincide with increases in sporadic notifications of the same pathogens, whereas decreases in toxin caused outbreaks followed the introduction of mandatory food safety training in retail food businesses. Recognizing issues in food production and implementing improvements that reduce the number of pathogens in food will be key to reducing the incidence of foodborne outbreaks.
Keywords: Australia; disease outbreaks; foodborne infections; surveillance.