Listeriosis

Listeriosis is an uncommon disease caused by the bacteria Listeria monocytogenes.

In the NT, 3 cases of listeriosis have been reported in the past 10 years.

Over the same time period, there has been an average of 73 cases per year reported throughout Australia.

How it spreads

The disease is generally spread by eating food contaminated with the bacteria.

This is most commonly found in ready-to-eat meats, and unpasteurised milk or other dairy products particularly soft cheeses.

It can also pass from a pregnant woman to her unborn baby via the placenta, or to the baby during birth.

Infection of an unborn baby usually occurs about 3 days after the mother is infected.

Exposure to the bacteria is generally unavoidable, as it's:

The following groups are at greatest risk of severe disease:

anyone who has a weakened immune system, due to chronic disease, diabetes, alcoholism or steroid treatment
the elderly
newborn babies
pregnant women and their unborn babies.

Symptoms may develop from a few hours to 3 months after exposure to the bacteria. They most often occur around 3 weeks later.

Young, healthy people may have few if any symptoms, but the disease can be severe in at-risk groups.

If symptoms do develop, these often include fever, headache, tiredness, muscle aches, abdominal cramps, nausea and diarrhoea.

Infection of an unborn baby may lead to miscarriage, stillbirth, premature birth or a seriously ill newborn.

If infection spreads to the nervous system, symptoms such as stiff neck, confusion, loss of balance and convulsions may occur.

Infected people can shed the bacteria in their faeces for several months.

Mothers of infected newborns may pass on the bacteria in vaginal discharges and urine for 7 to 10 days after giving birth.

Listeriosis can be effectively treated with antibiotics if treatment is given immediately.

Newborn infants have a high mortality rate (20% to 30%) despite antibiotic treatment.

Unlike most other food-contaminating bacteria, listeria can survive and grow in the refrigerator.

Although, it is readily killed during cooking.

General food hygiene measures should be followed, including:

thoroughly cooking raw food from animal sources, such as beef, pork or chicken
washing raw vegetables thoroughly before eating
keeping uncooked meats separate from vegetables, cooked foods and ready-to-eat foods
avoiding unpasteurised milk products
washing hands, knives and cutting boards after handling uncooked foods.

Additional precautions for pregnant women and those with weakened immune systems include:

eating only freshly prepared foods
re-heating left over foods or ready-to-eat foods such as hot dogs until steaming hot
avoiding ready-to-eat foods which have been refrigerated more than a day
avoiding eating dips and salad dressings that have been exposed to raw vegetables even if they have been refrigerated
avoiding high-risk foods such as:
- pâté
- pre-packed sliced meat products
- cooked diced chicken (as used in sandwich shops)
- soft cheeses (such as brie, camembert and ricotta)
- previously prepared coleslaws and salads
- uncooked smoked fish
- smoked shellfish
- any food with an extended shelf life
avoiding contact with animal placenta (after birth) and with aborted birth products.

To find out more, go to the NT Health website.

Contact your nearest Centre for Disease Control on the NT Health website.