Salmonella-Contaminated Eggs a Significant Source of Australian Foodborne Illness Outbreaks

bowl of eggs — Image credit: azerbaijan_stockers via Freepik

The Australian OzFoodNet network recently published its latest foodborne illness monitoring report, covering the year 2019. OzFoodNet monitors and responds to foodborne diseases in Australia, and its annual reports summarize the incidence and causes of diseases transmitted by food in a given year in the country.

In 2019, state and territory health departments in Australia received 55,622 notifications of enteric diseases potentially related to food, the majority of which were related to Campylobacter (66 percent or 36,451) infections or Salmonella (26 percent or 14,676) infections. This is consistent with previous years.

Other important foodborne pathogens that caused illness in 2019 include Shigella (6 percent, or 3,152 notifications) and Shiga toxin-producing Escherichia coli (STEC) (1 percent, or 655 notifications).

A total 121 foodborne illness outbreaks were reported in 2019, resulting in 2,428 infections, 402 hospitalizations, and four deaths. Eggs contaminated by Salmonella Typhimurium were a significant driver of foodborne illness outbreaks, alone causing 26 outbreaks affecting 936 people.

Salmonellosis outbreaks linked to all commodities caused more than half of all the foodborne illness outbreaks in 2019 (64 outbreaks, or 53 percent).

Norovirus caused the second most outbreaks (13, or 11 percent), affecting 522 people; followed by ciguatoxin (9 outbreaks, 11 percent), affecting 35 people; scombrotoxin (6 outbreaks, 5 percent), affecting 29 people; and Clostridium perfringens (5 outbreaks, 4 percent), affecting 63 people.

Although it caused the greatest number of isolated cases of foodborne illness in 2019, Campylobacter was only associated with one outbreak, affecting five people. A pathogen causing illness was not confirmed in 19 outbreaks (16 percent).

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A food vehicle was identified in 64 percent of outbreaks in 2019. Following eggs contaminated by Salmonella (26 outbreaks, 21 percent), the greatest number of outbreaks were caused by seafood (18 outbreaks or 15 percent) linked to Listeria monocytogenes infection (1 outbreak), methemoglobinemia (1), Salmonella infection (1), and scombrotoxin poisoning (6). Meat caused five outbreaks (4 percent).

Restaurants/cafés were the most commonly reported food production environment linked to outbreaks (59 outbreaks, 49 percent), followed by primary production (18 outbreaks, 15 percent) and commercial caterers (10 outbreaks, 8 percent).

Data for the OzFoodNet report was derived from the National Notifiable Diseases Surveillance System (NNDSS), which includes cases of infectious disease for which doctors and laboratories are required to submit notification. Notifiable enteric diseases in Australia include botulism, campylobacteriosis, cholera, hemolytic uraemic syndrome (HUS), hepatitis A, hepatitis E, listeriosis, paratyphoid fever, salmonellosis, STEC infection, shigellosis, and typhoid fever.

The OzFoodNet network comprises foodborne disease epidemiologists from each Australian state and territory health department, as well as collaborators from the Australian Government Department of Agriculture, Fisheries, and Forestry (Agriculture); Food Standards Australia New Zealand (FSANZ); and the Public Health Laboratory Network (PHLN).

The full OzFoodNet report for 2019 can be read here.

Bailee Henderson is the Director of Content Strategy for Food Safety Magazine. In the day-to-day, she covers industry-relevant current events, regulatory affairs, and scientific developments. She also produces the Food Safety Five Newsreel and edits the twice-weekly Food Safety Digest newsletter. Notably, Bailee's coverage for Food Safety Magazine has been featured in national televised news segments including CBS Sunday Morning and MSNBC's Rachel Maddow Show. She can be reached at hendersonb@bnpmedia.com.