It is understood the fourth victim died more than a week ago but the connection to the listeria outbreak could only be confirmed this week.
There is now 17 confirmed cases of listeriosis from eating rockmelon that came from a farm in New South Wales.
Victoria's Deputy Chief Health Officer, Dr Brett Sutton, yesterday said six cases have come from Victoria, impacting men and women aged between 60-90 years old.
Listeriosis is a bacterial infection that begins with flu-like symptoms such as fever, chills, muscle aches, nausea, and sometimes diarrhoea. In immunosuppressed patients, listeriosis usually presents as a brain inflammation, brain abscess or blood poisoning.
Listeria infection is particularly dangerous for pregnant women, unborn babies and elderly people.
Infection in pregnant women may be mild and a temperature before or during birth may be the only symptom. The infection can however be transmitted to the foetus through the placenta which can result in stillbirth or premature birth. Pregnant women should avoid eating pre-cut melons, including rockmelon.
The fruit has been removed from supermarkets as a result of the outbreak.
