More than 450 foodborne outbreaks were reported over a three-year period in Australia, according to a new study.

The 452 confirmed and suspected foodborne outbreaks affected 7,361 people, caused 705 hospitalizations and 18 deaths from 2013 to 2015.

Salmonella was the main agent identified and restaurants were the most frequently-reported food preparation setting. There were 213 outbreaks attributed to a single food with 124 linked to consumption of eggs and egg-based dishes.

A total of 129 outbreaks were recorded in 2013, 166 in 2014 and 157 in 2015. New South Wales reported the most in the period with 135.

More than 90 outbreaks were caused by an unknown agent, according to data from OzFoodNet, Australia’s foodborne disease surveillance system, published in the journal Communicable Diseases Intelligence.

Salmonella was responsible for 239 outbreaks. Salmonella Typhimurium was the most commonly-identified serotype in all years, accounting for 90 percent of these incidents.

Of outbreaks attributed to a single commodity, the foods mainly implicated were eggs followed by fish in 40 outbreaks and poultry in 27.

During the reporting period, having contaminated raw products was a factor reported for 132 outbreaks followed by cross-contamination from raw ingredients 50 times.

Large outbreak examples
Ten outbreaks affected more than 100 people. Six were because of Salmonella Typhimurium, three because of norovirus, and one with 125 patients was suspected to have been caused by a bacterial toxin in curried prawns. The largest Salmonella outbreak sickened 350 people due to potato salad with raw egg mayonnaise.

A 2013 norovirus outbreak that affected 525 people was linked to Tasmanian oysters. A leaking underwater sewer pipe was the suspected source of contamination. Overall, norovirus caused 35 outbreaks with 1,500 cases.

Campylobacter was implicated in 18 foodborne outbreaks during 2013 to 2015. Six had strong associations with consumption of poultry liver.

In 2014, the first locally-acquired outbreak of hepatitis E in Australia was identified and was related to consumption of pork liver pâté at a restaurant. In 2015, the first outbreak of hepatitis A in the country linked to consumption of imported frozen berries was detected.

Ciguatera fish poisoning was behind 29 outbreaks with 124 ill and eight were because of histamine with 31 patients. Eleven incidents were because of Clostridium perfringens and befermentans with 163 sick. E. coli only caused two small outbreaks and Listeria three with nine sick.

OzFoodNet sites reported increasing reports of 12 diseases or conditions that may be transmitted by food with 28,676 received in 2013; 37,958 in 2014; and 41,226 in 2015. The most common were campylobacteriosis and salmonellosis.