Australians have been urged to throw out or return rockmelons purchased before Wednesday February 28 due to a listeria outbreak responsible for two deaths in New South Wales.

NSW Health’s communicable diseases director Dr Vicky Sheppeard said last week in a statement the disease is caused by eating food contaminated with a bacterium called Listeria monocytogenes, which doesn’t cause illness in most people, but can be extremely harmful to those in high risk groups.

“The elderly, pregnant or those with underlying health conditions, which lead to a weakened immune system, form part of this group,” said Sheppeard. Infection during pregnancy, for example, can lead to miscarriage, stillbirth or infection of the newborn.

Listeria starts with flu-like symptoms such as fever, muscle aches and occasionally other symptoms such as nausea and diarrhea. These symptoms can take up to a few weeks to appear.

The outbreak has been linked to a grower in Nericon in the NSW Riverina region. The grower has issued a trade-level recall on its product, Australian Melon Association industry development manager Dianne Fullelove told Broadsheet.

“Any rockmelon on the shelf now is from farms that have tested negative to the disease, and other types of melons have not been implicated,” she said.

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NSW Health reported the outbreak of the bacterial infection on February 23 after an increase in reported cases across the state, before a connection to the fruit was made.

Out of fourteen reported cases of listeria this year, ten were found in elderly people who contracted the infection after consuming rockmelon. Other cases have been reported in Queensland and Victoria.