Recently we have seen an increase in the notifications of Listeria Mono through our routine food sampling and from the Department of Health. In these cases people have been diagnosed through their doctor or by being admitted to hospital with Listeriosis the result of eating foods contaminated with Listeria Mono.

Listeriosis is rare but for the elderly people with weak immune systems pregnant women and their unborn child the illness can be serious and cause death.

Eating foods contaminated with Listeria Mono is the most common way of contracting the illness and the symptoms may appear within 24 hours of eating contaminated food but can take up to two months for symptoms to develop.

The symptoms are not the typical ones we associate with food poisoning bacteria symptoms can include:

• fever
• headache
• tiredness
• muscle aches and joint pain
• nausea
• vomiting
• diarrhoea
• neck stiffness.

Even a small amount can cause illness. There is a zero tolerance to Listeria Mono being detected in food where it will grow. If it is detected an Environmental Health Officer will be in touch and a full Listeria clean of the premises is required which is then followed up with further sampling to ensure it is no longer present.

Listeria is naturally present in the environment. Foods at higher risk of contamination are ready to eat foods (that won"t be further cooked) such as salads and fruits cold ready to eat chicken deli meats seafood soft cheese soft serve ice-cream unpasteurised milk and raw vegetables.

Listeria is tolerant to low temperatures so it can grow in food even if it is stored in the refrigerator.

Some useful ways to help prevent Listeria and therefore Listeria Mono being present in your food business:

• wash salads fruit and vegetables (that will not be cooked) thoroughly under running water this should be done prior to cutting
• if drying salads fruits etc. use single use cloths/paper towels
• salads fruit and vegetables can also have a food safe sanitiser step added to the wash process to increase the effectiveness of cleaning - manufacturer’s instructions must be followed
• clean benches etc after containers / boxes have been put on them
• avoid putting produce boxes onto the preparation benches
• clean and sanitise all food preparation surfaces utensils equipment etc. between uses
• stock stored and rotated correctly raw and ready to eat separated and within use by and best before dates
• equipment utensils etc are maintained - no cracks chips melted damaged parts missing etc.
• use separate equipment were possible for raw and ready to eat foods - if this is not practical for your business ensure it is cleaned and sanitised between uses
• prevent cross-contamination throughout the premises
• cook foods thoroughly especially meat poultry and fish
• regular handwashing and glove changing
• clean uniform
• ensure food preparation surfaces are smooth impervious and easy to clean
• ensure the premises is well maintained easy to clean and kept clean
• repair damaged and poor floor drainage in kitchens damaged flooring and areas where water can pool can be a collection point for Listeria
• avoid accumulation of condensation in refrigerators and blast chillers this can create favourable conditions for listeria which may be distributed via dripping or moist air blown through the units.

Watch the short video on Listeria by Food Standards Australia New Zealand.

Further information on Listeria in Food by Food Standards Australia New Zealand