Listeriosis is a foodborne illness that results from eating food contaminated with a bacterium called Listeria. Listeria is found widely in soil, water, and plants and in the droppings and faeces of animals and humans. Outbreaks of listeria are often linked to ready-to-eat products and foods with a long refrigerated shelf life.

Doctors are legally required to notify the Public Health Service of cases of Listeriosis. The disease is uncommon in New Zealand, with only 20 – 40 cases notified per year. The Nelson Marlborough Public Health Service investigates cases of Listeriosis and where a link to a food premises is confirmed, works with the Ministry for Primary Industries to prevent further spread of the disease.

Symptoms

Symptoms usually appear within 2 to 30 days of eating contaminated food, but it can take up to 70 days before people experience symptoms. A person could have no symptoms at all or may become ill with:

  • mild fever
  • headache
  • aches and pains
  • nausea or vomiting
  • diarrhoea

In a small number of cases these symptoms can progress to more severe forms of the illness, such as meningitis and blood poisoning. In pregnant women, symptoms may be mild, but the consequences can be severe because listeriosis can result in miscarriage, premature birth or stillbirth and can also cause severe infection in newborn babies.

Contact your GP or Healthline (0800 611 116) for further advice.

Prevention

The risk of serious illness from listeria infection can be reduced by safe food handling practices. Listeria is one of the few food bacteria that will grow on food even if it’s in the fridge and can withstand freezing. It is wise to store any perishable food in the fridge, but it is also important to use it within two days.

If you are in a group at higher risk of listeriosis, you can reduce the risk of infection by:

  • eating only foods that are freshly prepared and well washed
  • following good food hygiene practices, including washing and drying hands
  • cooking foods thoroughly to kill any listeria
  • refrigerating leftovers immediately and not keeping them for more than 2 days
  • reheat food to steaming hot (over 70 degree Celsius) before eating
  • avoiding foods that are at high risk of Listeria (eg uncooked, smoked or RTE fish, seafood, or sushi, pate, precooked meat products, RTE salads, raw milk, soft serve ice creams or soft cheeses).

Exclusion from work, school or Childcare

Stay away from work, school or childcare if you have diarrhoea or vomiting and don't return until all symptoms have stopped for 48 hours.