Prevention of listeriosis

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What is listeriosis?

Listeriosis is a food-borne infectious disease that is caused by the bacteria Listeria monocytogenes. The bacteria are present in the environment and are transmitted to humans through contaminated food, including dairy products (unpasteurised milk, certain cheeses etc.), uncooked pork products, raw meat and fish, and raw vegetables and salad. The bacteria are also resistant to refrigeration temperatures (4°C). Those primarily affected are pregnant women, newborn babies, elderly people and those with a compromised immune system.

What are the symptoms?

The incubation period for listeriosis can range from a few days to two months from when the contaminated food was ingested.

Among pregnant women, the infection may come and go unnoticed or it may manifest itself as a fever with flu like symptoms (shivers, headaches, fatigue, aches and pains) accompanied by contractions.
The bacteria present in the maternal blood can infect the foetus and lead to complications, such as spontaneous abortion or premature birth with serious implications (respiratory distress, septicaemia, neurological damage and, more rarely, skin problems). Neonatal listeriosis can occur at any point during pregnancy.

How can I avoid contracting listeriosis during my pregnancy?

You should avoid eating:
• Unpasteurised milk or food containing unpasteurised milk
• Semi-hard cheeses and soft cheeses made from unpasteurised milk, blue cheeses; it is generally advisable to remove the rind from cheese
• Raw fish (sushi), seafood, raw meat (carpaccio, rare meat), uncooked pork products (salami, cured ham, smoked sausage) and smoked fish (smoked salmon or trout)
• Pre-cut and pre-packaged salad and vegetables

Practise good food hygiene:

• Refrigerate uneaten food immediately and eat it soon after; take note of expiration dates and time limits for keeping food in the fridge.
• Clean your fridge regularly and ensure that food items do not touch each other (using cling film); ensure that food from the fridge is reheated sufficiently.
• Wash vegetables thoroughly and wash your hands before and after handling raw meat and poultry
• Ensure that meat and fish are properly cooked.
• Do not use the same utensils or chopping boards for cooked food and raw food.

L. monocytogenes grows at refrigeration temperatures, survives being frozen and is killed at cooking temperatures.

Am I at risk?

Yes, pregnant women in all stages of pregnancy and newborns are particularly at risk.

What are the risks to my baby?

The infection can cause miscarriages or early labour with serious consequences for the newborn baby (septicaemia, meningitis). The mother can transmit the infection to the foetus in utero through the placenta or, in exceptional cases, during labour.

What treatments are available?

Listeriosis is treated with antibiotics.

Advice

Preventive measures include practising good food hygiene and avoiding any foods that may be contaminated.

Diagnosis/detection

No screening; serology is not recommended.
Diagnosis if symptoms are present; haemocultures.

Published by Medisupport Services SA, Version 2022