Listeria: symptoms, foods, incubation, what is it?

Listeria bacteria can contaminate several categories of food and cause listeriosis, a disease that can be serious. Pregnant women are particularly at risk; they can transmit the bacteria to the fetus during pregnancy or during childbirth. What are the symptoms to watch out for? What to do?

What is listeria (listeriosis)?

Listeria monocytogenes is the name of the bacteria responsible for listeriosis, a rare but potentially serious infection.Listeriosis is mainly transmitted by ingestion of contaminated food by bacteria present in soil, vegetation and water“, explains Dr Jacques Amselem, general practitioner in Seine-et-Marne. Fortunately, it has few consequences for the majority of individuals. Two exceptions:

• At the pregnant woman, it can go unnoticed but lead to spontaneous abortion or premature birth, and her baby.
• At the newborn, Listeriosis can in fact cause skin, respiratory or neurological conditions.

How many cases of listeriosis in France?

Human listeriosis is a notifiable disease in France since 1998: the doctor or medical analysis laboratory must inform the health authorities when it detects a case of listeriosis. Its incidence decreased until 2001, stabilized from 2001 to 2006, then has been increasing steadily since 2006 to reach in 2023, 300 to 400 cases of invasive listeriosis declared each year in France. It is the 2nd cause of food-related mortality in France. More than 80% occur in fragile people (pregnant women and newborns, people aged over 65, immunocompromised people).

Cooking destroys the bacteria

What symptoms?

• diarrhea,
• abdominal pain,
• nausea, vomiting
• fever, headache, body aches.

In a pregnant womanlisteriosis manifests itself with flu-like symptoms such as isolated fever, chills, lower back pain.

What is the incubation period for listeriosis?

Incubation is generally 10 to 28 days.

Contamination is caused by consumption of infected food by the listeria (poorly washed vegetables, cold meats, raw fish… See the full list below). Unlike other bacteria, this one can multiply even when food is stored in the refrigerator. Cooking destroys the bacteria. Therefore, it is advisable to cook meat and fish well. Above 65°C, the bacteria is killed.

What foods can cause listeriosis?

• Raw or smoked fish
• Shellfish and crustaceans
• The charcuterie
• Surimi
• Raw milk
• Raw milk cheeses
• Raw sprouted seeds…

“To protect against this infection, pregnant women must avoid consuming the most frequently contaminated foods, starting with fish, raw or smoked, and shellfish“, recommends Dr. Amselem. Surimi, cold meats (rillettes, foie gras, etc.), raw milk and raw milk cheeses, raw sprouted seeds like those of soya, must also be discarded. It is also recommended to remove the rind from cheeses, cook foods of animal origin thoroughly and wash vegetables and aromatic herbs thoroughly.

Who is especially at risk?

“THE elderly people (from 65 years old), newborns and pregnant women are people particularly exposed to the risk of listeriosis. People with weakened immune systems are also more likely to contract listeriosis“, specifies Dr Jacques Amselem. In particular, people under immunosuppressive treatment, with an autoimmune disease, an infection with HIV For example. THE people suffering from cancerblood or liver disease (cirrhosis, etc.), insulin-dependent diabetics and those who have undergone organ transplant are also more at risk, underlines theHandles. It is therefore necessary to be clearly more vigilant in his people. In pregnant women, the infection can cause spontaneous abortion, A premature birth or an infection of the newborn (sepsis, pulmonary, neurological, skin infection) with a fatality rate of 20% for the infant.

The diagnosis is made in people who present symptoms of contamination. It is based on the isolation of the bacteria following a blood sample, a vaginal sample, gastric fluid in a newborn or a lumbar puncture.

What is the treatment for listeriosis?

“The treatment of listeriosis is based on administration of antibiotics“, reports the doctor. In 20% of cases, this contamination leads to death, most often in patients already weakened by another illness. In the two months following the consumption of infected food, it is recommended to monitor the If symptoms appear, a medical consultation is necessary.

Can we die from it?

Yes, but listeriosis is especially dangerous in the fragile people mentioned above. At their house “the symptoms of listeriosis can worsen and persist for several weeks in the form of septicemia, meningitis, brain abscesses, or even local infections. Neurological after-effects can be observed and, according to studies, THE death rate due to infection varies from 20 to 30%” indicates Anses. Listeriosis has a very high hospitalization rate (>97%).

• Wash your hands thoroughly, especially after using the toilet and before preparing food. Hands are the primary vectors of germs in food.
• Adjust the temperature of your fridge (+4°C at most) and refrigerate food quickly after purchasing it.
• Store leftovers in the refrigerator for less than 3 days.
• Do not place unpackaged food directly on the shelves.
• Ensure good hygiene in the refrigerator.
• Avoid cooked or raw charcuterie products consumed as is (cooked or raw ham, jelly products, foie gras, pâté, rillettes, etc.), seafood products (smoked fish, tarama, raw shellfish, etc.) and certain products. dairy (raw milk, soft cheese with bloomy or washed rind), especially for people at risk such as pregnant women.

Thanks to Dr Jacques Amselem, general practitioner in Seine-et-Marne.