An investigation into a series of deaths linked to listeria on rockmelons has concluded the contaminated fruit came from a single farm in New South Wales, and the outbreak was largely caused by the weather.
Between January 16 and April 10 of this year, 22 cases of listeriosis occurred across New South Wales, Victoria, Queensland and Tasmania, which led to seven deaths and a miscarriage.
The investigation found the farm that was the source of the outbreak had hygiene and sanitary procedures on par with or better than most rockmelon-growing operations.
Dust storms that covered the farm's paddocks significantly increased the amount of listeria on the fruit There were other peripheral issues found in the packing facility that were not considered to be major underlying causes
A report released on Thursday by the NSW Department of Primary Industries confirmed those cases were all linked to consumption of rockmelon packed at Rombola Family Farms in Nericon, NSW. The report said the farm's hygiene and sanitary procedures were "on par with or better than most other rockmelon-growing operations across Australia".
Despite this, heavy rains in December and dust storms that followed covered the farm's paddocks in dust, and "significantly increased" the amount of listeria on the fruit. Rockmelons on the farm were washed in a chlorine solution and scrubbed prior to packing.
"The wash water was not recirculated, sanitiser was constantly monitored and applied through an auto-dosing system, and all water coming into the facility was treated and considered potable," the report said. "The netted skin of rockmelons makes this fruit particularly hard to clean and sanitise."
Many rockmelon growers called for the farm that was the source of the outbreak to be named, in order to reassure the public that the fruit was safe to eat. Industry development manager Dianne Fullelove told Fairfax Media in September the industry had not recovered, and many growers had left the industry. The listeria contamination and the recent strawberry needle scandal have given rise to calls for better ways to alert the public to risks in the food chain.