Dr Danie Schneider
Obstetrician and Gynaecologist, Somerset West

Listeriosis

What is Listeriosis?

Listeriosis is an infection caused by the Listeria monocytogenes bacteria, often called just Listeria. Listeriosis is typically caused by eating food that has been contaminated with Listeria. Some of the foods that are more likely to be contaminated with Listeria include unpasteurized milk, uncooked meat and fish, uncooked vegetables, lunch (deli) meat and soft cheeses. Listeriosis can be mild or severe. It is however not usually serious in healthy people and infection would last only about 2 days.

What are the symptoms of Listeria?

A non-specific flu-like illness is the most common presentation. Other symptoms include fever, chills, diarrhea, muscular pain and back pain. The infection may often be mild and resolve without therapy.

Why is this infection important in pregnancy?

Avoiding deli meat while pregnant because of listeria risk

Like other infections e.g. flu and chicken pox, Listeriosis can be more dangerous in pregnant women. Analyses from previous outbreaks show that pregnant women are more likely to develop Listeriosis than the general population. Pregnant women, especially those in the third trimester, are particularly susceptible to Listeria infection and account for up to one-third of reported cases.

A pregnant woman can pass Listeria to her unborn baby and the unborn baby can get very sick. While it may be possible to pass Listeria on to an infant through breast milk, there are no reports of infection occurring in this way.

I have ingested food implicated in the recent outbreak, should I be worried?

It is important not to over react and be influenced by media hype. It is sensible to follow the guidelines given by the Center for Disease Control that was drawn up during a recent outbreak in the USA. From their experience it is recommended that tests should only be done if you develop symptoms e.g. diarrhea or a fever. Preventative antibiotics are not advised unless symptoms develop, e.g. high fever.

Are there tests available to diagnose Listeria?

It is generally advised that blood cultures should be considered in any pregnant woman who has a fever, when no alternative explanation (e.g. bladder infection or pharyngitis/throat infection) is readily apparent.

Stool culture is not accurate.

Can Listeria be treated in pregnancy?

Large doses of antibiotics such as ampicillin or penicillin are recommended and have a proven success record. Therapy for maternal listeriosis with high doses of antibiotics has resulted in successful therapy for the developing baby, leading to lower incidences of complications.

Can Listeria harm my baby?

Listeriosis has not been linked to a pattern of birth defects. Listeria infection during pregnancy can increase the risk of miscarriage, stillbirth, uterine infection and preterm delivery. Listeriosis during pregnancy can also increase risk for health problems for the newborn.

It is important to realize that not all babies whose mothers are infected during pregnancy will have problems due to listeriosis. Early diagnosis and treatment with high doses of antibiotics may prevent infection of the unborn baby and result in the birth of a healthy infant.

How can Listeria be prevented?

People can get Listeria from eating spoiled food. Sometimes, it can be hard to tell if food is spoiled and therefore it is recommended to avoid certain food such as raw milk, soft cheeses, and deli meats.

General guidelines for pregnant women include:

Do not drink unpasteurized milk (also called raw milk) or eat any foods made
with unpasteurized milk.
Thoroughly cook raw foods from animal sources.
Wash raw vegetables as well as fruits.
Keep your refrigerator at or below 4 degrees Celsius and clean your
refrigerator regularly.
Do not eat soft cheeses (such as feta, Brie, Camembert, blue-veined
cheeses).
Reheat to steaming any leftover and ready-to-eat food, such as hot dogs,
cold cuts and deli meat.
Take care to not get the juice of deli meats and hot dogs on other foods or
surfaces and wash your hands after handling deli meats and hot dogs.
Do not eat refrigerated paté, meat spreads or refrigerated smoked seafood,
unless it is an ingredient in a fully cooked dish (like a casserole).