Salmonella top cause of foodborne outbreaks in Australia

[عبد الرحمن الجارحي]

Salmonella dominated reported outbreaks in Australia in 2016 causing several large incidents, according to a study published recently.

A total of 177 foodborne outbreaks were reported affecting 3,639 people, with at least 348 hospital admissions and four deaths. A food vehicle was identified in 109 outbreaks, researchers report.

Salmonella was the most frequently-identified agent in outbreaks in 2016, responsible for 73 incidents and more than 2,000 illnesses with almost 300 hospitalizations, according to the study published in the latest edition of the Communicable Diseases Intelligence journal.

A previous article covered Australia’s annual surveillance report of notifiable diseases for 2016.

The three largest outbreaks were Salmonella Anatum associated with bagged salads with 311 sick, Salmonella Saintpaul traced to mung bean sprouts affecting 419 people and a Salmonella Typhimurium outbreak linked to a bakery with 202 cases. Salmonella Typhimurium was the most commonly identified serotype with 64 Salmonella outbreaks in 2016.

A Salmonella Hvittingfoss outbreak affected 144 people in six states. Half of the patients were younger than 5 years old and almost a quarter were over the age of 65. South Australian authorities detected Salmonella Hvittingfoss and other serovars on retail samples of rockmelon, also known as cantaloupe, from the implicated grower.

“These outbreaks highlight the risks associated with fresh raw produce and the ongoing need for producers, retailers and consumers to implement strategies to reduce potential Salmonella contamination,” said researchers.

Eggs frequently implicated
Eggs continue to be a source of Salmonella Typhimurium infection across the country: 35 egg-related outbreaks, affecting 510 people with 89 hospitalizations, were reported across six jurisdictions in 2016. The largest incident was linked to scrambled eggs and affected 143 people.

Egg-related outbreaks mainly resulted from consuming food prepared at a restaurant, followed by a private residence. Thirteen of them were associated with eggs in desserts, including tiramisu, chocolate mousse and fried ice cream.

Ten outbreaks were linked to consumption of egg-based sauces and dressings such as mayonnaise, aioli and hollandaise sauce. Other implicated egg-containing vehicles included breakfast dishes and milkshakes.

Seafood, including fish, mollusks and crustaceans, was implicated as the source in 25 outbreaks. They were caused by ciguatoxin 14 times, scombrotoxin on four occasions and twice each by norovirus and Vibrio parahaemolyticus.

Restaurants were the top food preparation setting, accounting for 82 foodborne outbreaks and 1,338 ill people reported as part of outbreaks in 2016.

Other causes of outbreaks
Fifteen norovirus outbreaks sickened 511 people while 14 Ciguatoxin outbreaks affected 56 people.

Ten Campylobacter outbreaks involved 100 people; 87 were sick in six Clostridium perfringens epidemics. Nine patients were recorded in four scombrotoxin events.

Two Vibrio parahaemolyticus outbreaks sickened 20 people and two Shigella ones affected 10 people. One Staphylococcus aureus outbreak affected 24 people and another caused by Bacillus Cereus made 20 people sick. There was no mention of E. coli. A total of 48 incidents were caused by an unknown agent.

Eight patients were recorded in a Listeria outbreak. Of seven cases interviewed, all consumed cold meats, cheeses and/or salads from various deli counters in the four weeks prior to onset. Food samples and environmental swabs isolated Listeria monocytogenes with the same genetic profile from three supermarket delicatessens and from a ham production facility in New South Wales that distributed products to various supermarkets implicated by cases.