Hysteria around Listeria

Listeria has been in the news recently after lettuce was recalled due to a contamination. But what exactly is Listeria? What can it cause and who in particular is at risk? We hope to ease some of the hysteria around listeria for you and to help you keep informed and safe.

What is Listeria?

Listeria a type of bacteria that is widely found in the environment in soil and water and can cause a type of food poisoning. There are six known species of Listeria, however only L . monocytogenes is known to cause illness in humans. Listeria, unlike other contaminating bacteria continues to grow at refrigerator temperatures.

Listeria can be mild or severe however it rarely affects healthy individuals. But it can be more dangerous for pregnant women and their fetuses, newborns, the elderly and those with a weakened immune system and can be life threatening.

What are the symptoms of Listeria infection?

Listeria has a long incubation period and as a result the illness normally occurs between 2 to 8 weeks after eating contaminated foods. The symptoms are different depending on which part of the body is affected.

People with Listeria infection in the brain and spinal cord can have:

  • Fever
  • Headache
  • Nausea and vomiting
  • Stiff neck
  • Confusion
  • Weak muscles on one side of the body, trouble walking or shaky hands
  • Seizures

People with Listeria infection in the bloodstream can have:

  • Fever
  • Chills
  • Dizziness
  • Low blood pressure
  • Fast heart rate
  • Pain in joints and muscles

People with Listeria infection in the digestive system can have:

  • Fever
  • Watery diarrhea
  • Nausea and vomiting
  • Headache
  • Pain in joints and muscles

Should I see a doctor or nurse?

Call a doctor or nurse if you have any of the symptoms listed above and you are pregnant, older, have a serious medical condition, or take medicines that weaken the immune system.

Call a doctor or nurse if your newborn baby:

  • Gets sick with a fever or any of the other symptoms listed above
  • Acts differently from normal, such as feeding less than usual, breathing faster than usual, or looking sleepier than usual


Listeria can be diagnosed through a few different tests depending on your symptoms and medical requirements; these include blood test, spinal fluid sample, stool sample or even brain imagery. Pregnant women, newborn babies, and people with serious Listeria infections are treated with IV antibiotics. Healthy people with Listeria that affects the digestive system don’t usually need treatment. The infection usually goes away on its own in about 2 days.


Prevention is best and the risk of Listeria can be reduced by paying attention to food hygiene. This includes ensuring correct storage, preparation and cooking of food (for more information on this please visit http://www.mpi.govt.nz/food-safety/food-safety-for-consumers/tips-for-food-safety/). For those in high-risk groups it is recommended to avoid certain foods, these include:

  • Deli meats
  • Uncooked seafood
  • Refrigerated smoked fish products unless cooked
  • Paté
  • Soft cheeses such as camembert, brie, feta and blue vein.
  • Unpasteurised milk or dairy foods.

You should also talk with your healthcare professional about which foods to avoid.


For more information contact your healthcare professional.

The information contained on this site is not intended to be a replacement for medical advice or advice in relation to the health or care of any person. The information is generalised and should not be relied upon as a substitute for professional clinical advice. If you have any questions relating to the information you should seek the advice of a qualified medical practitioner. The information is derived from a number of sources. Hillcrest Pharmacy has endeavoured to ensure that all information is from reliable and reputable sources.