What is the issue?
Listeriosis is an illness usually caused by eating food contaminated by the bacterium Listeria monocytogenes. Listeria monocytogenes is widely distributed in the environment, and can grow in food at refrigeration temperatures. Although uncommon, listeriosis is dangerous to those who are susceptible.
The Department of Health and Human Services has observed an increase in notifications of listeriosis in pregnant women and the elderly over recent weeks. Although these cases have not been linked to each other or to a particular food, health professionals should be aware of the risk of listeriosis over summer.
Who is at risk?
While anyone can develop gastroenteritis due to listeriosis, certain groups of people are more at risk of invasive infection. These groups are pregnant women, newborns, older adults and people with weakened immune systems.
Symptoms and transmission
The primary mode of transmission is through the consumption of contaminated food, however transmission can also occur in utero.
Listeriosis during pregnancy typically presents as flu-like illness, with fever, fatigue and muscle aches. Some pregnant women with listeriosis may have no symptoms. Infection during pregnancy can result in miscarriage, stillbirth, preterm labour, and sepsis or meningitis in the neonate.
In immunosuppressed patients, listeriosis usually presents with sepsis, meningitis or meningoencephalitis. Focal infections such as pneumonia, endocarditis and granulomatous lesions in the liver and joints have also been described.
Healthy adults may experience flu-like symptoms and self-limiting gastroenteritis.
It is important to educate at-risk people to handle, prepare and store food safely.
Individuals at risk of listeriosis should particularly avoid:
- ready-to-eat seafood such as cooked chilled prawns, smoked fish or mussels, oysters or raw seafood such as sashimi or sushi
- pre-prepared or pre-packaged fruit and vegetable salads and sandwiches including those available from buffets, salad bars and sandwich bars
- drinks made from fresh fruit and vegetables where washing procedures are unknown (excluding pasteurised or canned juices)
- deli meats which are eaten without further cooking or heating, such as pate, ham, Strasbourg (Stras), salami and cooked chicken (whole, portions or diced)
- any unpasteurised dairy products
- soft-serve ice creams
- soft cheeses such as brie, camembert, ricotta, blue and feta (these are safe if cooked and served hot)
- ready-to-eat foods, including leftover meats, which have been refrigerated for more than one day
- dips and salad dressings in which vegetables may have been dipped
- raw vegetable garnishes.
Antibiotic treatment should be prescribed as per the current Australian therapeutic guidelines: antibiotic.Treatment should be guided by an infectious diseases specialist.
Disease information and advice - Listeriosis
Better Health Channel - Food poisoning - Listeria
Communicable Disease Prevention and Control Unit
Department of Health and Human Services
Telephone: 1300 651 160
Fax: 1300 651 170
Dr Finn Romanes
Acting Chief Health Officer
Authorised by the Victorian Government, 1 Treasury Place, Melbourne.