There have been 10 recent Listeria cases reported, traced back to rockmelon. All affected were elderly with underlying medical conditions.
NSW Health states that "Listeria is an illness usually caused by eating foods contaminated with the bacteria known as Listeria monocytogenes. Listeriosis is a serious disease in pregnant women and people with weakened immune systems. Infection is treated with antibiotics."
It is important to note that Listeria is uncommon in people with robust immune systems.
The NSW Food Authority is also advising consumers who are at risk of listeriosis to avoid eating rockmelon and discard any rockmelon they already have at home.
The NSW Health Listeriosis fact sheet has the following information:
What are the symptoms?
The incubation period (between infection and symptoms) can vary from three to 70 days but on average is about three weeks. Infections may cause septicaemia (blood poisoning) and meningitis (inflammation of the brain). Infection during pregnancy can lead to miscarriage, stillbirth and infection of the newborn.
Symptoms include: fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea and diarrhoea. In the more severe form, symptoms also include collapse and shock. If infection spreads to the central nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, convulsions and coma can occur. About a third of these patients may die.
How is it spread?
Listeria are widespread throughout nature, being commonly carried by many species of both domestic and wild animals. Raw meat, unpasteurised milk, raw fruit and vegetables can be contaminated with the bacteria. People who are at risk can contract listeriosis through eating food contaminated with the Listeria bacteria. Babies can be born with listeriosis if their mothers eat contaminated food during the pregnancy. Outbreaks of illness have been associated with raw milk, soft cheeses, pre-prepared salads (for example, from salad bars), unwashed raw vegetables, paté, cold diced chicken and pre-cut fruit and fruit salad.
Who is at risk?
Pregnant women and the foetus, newborns, the elderly and people with weakened immune systems (for example: people on cancer treatment or steroids, and people with diabetes, kidney disease, liver disease and HIV infection).