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 food poisoning caused by listeria include include a 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 handling and consuming it. If you notice symptoms of a listeriosis infection, be sure to consult a family doctor, gastroenterologist or infectious disease specialist for assessment and treatment as needed.

Main symptoms

The most common symptoms of a listeria infection are:

Diarrhea
General malaise
Nausea and vomiting
Muscular pain
High-grade fever, over 38ºC (or 100.4ºF)
Headache
Loss of appetite
Confusion
Fatigue

Gastrointestinal symptoms of listeriosis can appear up to 24 hours after consuming contaminated food or water, and can last between 2 and 3 days.

In more serious and rare cases, Listeria monocytogenes bacteria can spread through the bloodstream and reach the nervous system. This can lead to meningitis, which is an inflammation of the membranes surrounding the brain. Furthermore, infections in pregnant women can be serious and result in premature birth or infection at the time of delivery.

Confirming a diagnosis

A listeria infection, or food poisoning, is diagnosed by a family doctor, infectious disease specialist or gastroenterologist, who will start by assessing the presenting signs and symptoms.

To confirm the infection, the doctor may order bloodwork and stool testing to identify the bacteria causing the infection. In more severe cases, the bacteria can also be confirmed through a gastric lavage or amniocentesis (in pregnant women), or by performing testing on the food source that caused the infection.

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.