Listeria: What Is it, Listeriosis Symptoms, & Treatment

Listeria is a bacteria found in soil, iodine and water that can cause an infectious illness called listeriosis. This bacteria is usually transmitted through contaminated water and food, like unpasteurized milk, cheese, veggies, seafood and sausage. It is often the bacteria behind many outbreaks in food distribution that lead to food poisoning. 

A listeria infection is often asymptomatic, although symptoms are most commonly seen in groups with compromised immune systems like children, older adults, pregnant women and patients with chronic diseases. The initial symptoms of listeriosis present similarly to a flu and include fever, body ache and chills, with diarrhea appearing later on. 

To prevent contamination from a listeria outbreak, you should ensure adequate hand hygiene and thoroughly wash your food before consuming it. If listeriosis has been diagnosed, you should monitor all hygiene practices to avoid further transmission to others. 

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Listeriosis symptoms

Symptoms of listeriosis can occur 3 to 60 days after initial contact with listeria bacteria. Intensity of the symptoms will depend on the person's overall health status. Severe symptoms, which are associated with food poisoning, are usually noted in those with a weakened immune system. 

The main symptoms of a listeria infection are: 

  • Muscular pain 
  • High-grade fever, over 38ºC (or 100.4ºF) 
  • Vomiting
  • Chills
  • Headache
  • Loss of appetite
  • Diarrhea 
  • Confusion
  • Fatigue

In more severe and rare cases, listeria can enter the bloodstream and reach the nervous system. This can lead to meningitis, which is an inflammation of the membranes that line the brain. Infections in pregnant women can also be life-threatening to the baby and may lead to premature birth or transmission of the infection during delivery. 

Therefore, if you notice any signs or symptoms of listeriosis, you should seek medical attention to confirm a diagnosis. Diagnosis can be confirmed through a blood test or stool test, through a gastroscopy or through an amniocentesis for pregnant women. 

Read more about how intestinal infections present and how they are typically caused. 

Listeria transmission

Transmission of listeria occurs mainly through consumption of contaminated food or water. It can be found in unpasteurized milk, dairy products, fruits, greens, meat, fish, seafood, and sausage. It has a high transmission rate when outbreaks are declared, as this bacteria is easily distributed to many people through contaminated packaged foods.

This bacteria is resistant to many stress conditions in the processing of food, which is why it can be found in small concentrations in processed food. The presence of listeria in food does not always lead to infections as long as the food is properly stored to prevent bacterial growth.  

Treatment options

The treatment of a listeria infection usually involves the use of antibiotics like penicillin or gentamicin. Patients with a penicillin allergy may be prescribed sulfamethoxazole-trimethoprim. Check out the food poisoning medications that your doctor may prescribe. 

People who present with vomiting or diarrhea are advised to drink plenty of water and electrolytes to prevent further losses and dehydration. You should also maintain a light, easy-to-digest diet. 

See the home remedies for intestinal infections that you can use to compliment your medical treatment. 

How to prevent listeriosis

To prevent listeria contamination, you should adopt some hygiene measures like: 

  • Washing your hands before eating 
  • Ensuring raw foods are properly washes
  • Storing food appropriately 
  • Keeping your fridge clean
  • Avoiding consumption of unpasteurized food products 

To prevent new cases of listeriosis in the household, you should monitor your hygiene practises at home very closely and avoid sharing objects like cutlery and dinnerware.