Listeria infection: symptoms and advice

Listeria infections can be life-threatening. They're especially dangerous for pregnant women and newborns, older people, and the immuno-compromised. Find out about the symptoms and what to do to lower the risk of getting sick.

Listeria can be life-threatening for certain people

Listeria infections are rare but can be life-threatening, especially for high-risk groups. It's most dangerous for:

  • pregnant women
  • newborns
  • older people
  • anyone with a weakened immune system.

Food safety information for high-risk groups

Food safety advice for people with low immunity

Food and pregnancy

People at high risk should contact a doctor straight away if they think they’re infected.

Most people recover fully. Healthy adults will probably only get mild flu-like symptoms or gastroenteritis.

Symptoms of Listeria poisoning

Listeria bacteria cause the illness listeriosis.

This has 2 forms – invasive and non-invasive. The invasive form is much more serious.

Non-invasive symptoms include:

  • diarrhoea
  • fever
  • muscle pain
  • headache
  • occasional abdominal cramps
  • vomiting.

Symptoms usually appear within 2 to 3 days of eating food containing listeria.

Invasive symptoms include the non-invasive symptoms above, as well as other, more serious symptoms.

Invasive listeriosis symptoms 

Complications can include:

  • meningitis
  • blood poisoning (septicaemia).

When pregnant women get invasive listeriosis, it can result in:

  • miscarriage and stillbirth
  • perinatal infection
  • neonatal infection (sepsis or meningitis).

These can take weeks to show. See a doctor straight away if you think you're infected.

How you can get sick

About 90% of listeria infections come from eating food or drink that have high levels of Listeria.

Higher-risk foods include:

  • ready-to-eat products, like deli meats and salads
  • raw (unpasteurised) milk
  • smoked seafood (especially smoked fish)
  • soft cheeses (like brie and camembert), especially if made with raw milk
  • some fruits (like melons)
  • vegetables (especially green, leafy ones) and salads made from these
  • refrigerated foods with a long shelf life
  • sliced processed meat and poultry (like chicken) – especially in factory sealed packages
  • products sold in deli counters, like pâtés and ready-cooked meals.

A list of high-risk foods for Listeria and safer substitutes [PDF, 719 KB]

Listeria also lives in soil and water. Once Listeria is in food, it can multiply quickly. Unlike other harmful bacteria, it can still grow in the fridge, even at temperatures colder than 2°C.

Cross-contamination of infected food

If you're not careful, you can spread harmful germs to different food and surfaces. For example, if you cut raw chicken then use the same knife and chopping board for other food, the germs can spread. This can increase the risk of getting sick. This is called 'cross-contamination'.

To help avoid this, separate foods to prevent germs spreading. Use different chopping boards and knives, and wash your hands.

How to lower your risk of getting sick

To lower the risk of infection, you can:

  • eat food only that was well washed and recently prepared
  • wash and dry hands thoroughly, and follow good food hygiene practices
  • cook food thoroughly
  • refrigerate leftovers quickly, and not keep them for more than 2 days
  • reheat food to steaming hot (over 70°C) before eating.

Our Listeria research and risk management work

We do research and risk management work on Listeria and other foodborne illnesses.

Food safety research and risk management

Find out more

Get tips on preparing and storing food safely at home

Learn about Clean, Cook, Chill

Find out about other foodborne illnesses

Learn more about raw milk and its risks

Food safety when you're sick

Who to contact

If you have questions about listeria infection, email info@mpi.govt.nz

Last reviewed: