Listeria Infection

What Is Listeria?

Listeria infection, also known as listeriosis, is a serious illness caused by the bacteria Listeria monocytogenes. This bacteria can be found in soil, water, and some animals – sometimes making its way into our food. People usually get sick from eating food contaminated with the bacteria.

While healthy people may only have mild symptoms or none at all, listeria can be dangerous for certain groups, including:

• Pregnant people
• Newborns
• Adults over age 65
• Anyone with a weakened immune system

Listeria can spread beyond the gut to the nervous system, causing conditions like meningitis or even blood infections in severe cases.

How Do You Get Listeria?

You can get listeria by eating food that contains the bacteria. Listeria grows well in cold environments, so even refrigerated foods can be risky if contaminated.

Common sources include:

• Unpasteurized milk or soft cheeses (like feta, brie or queso fresco)
• Deli meats and hot dogs (if not heated properly)
• Refrigerated smoked seafood
• Prepared salads (like egg, tuna or chicken salad)
• Raw sprouts and raw milk products
  
  

In rare cases, listeria can also spread from mother to baby during pregnancy or birth.

Listeria Symptoms

Symptoms can appear a few days to over a month after eating contaminated food. They may start off mild and include:

• Fever
• Muscle aches
• Nausea or diarrhea
  ​

If the infection spreads beyond the digestive system, more serious symptoms can develop, such as:

• Headache
• Stiff neck
• Confusion
• Loss of balance
• Seizures
  ​

Pregnant people may only have mild flu-like symptoms but are at risk of complications such as miscarriage, stillbirth or early delivery.

How Is Listeria Diagnosed?

If your health care provider suspects listeriosis, especially after recent food-related symptoms, they may:

• Ask about recent food consumption (especially high-risk items)
• Order a blood test or spinal fluid test to look for the bacteria
• Evaluate symptoms and medical history
  ​

Because listeria can take a long time to show up, diagnosis can be tricky. Quick testing is important to begin treatment and avoid serious illness.

How Is Listeria Treated?

Listeria is treated with antibiotics, especially if the infection has spread. Early treatment is key to preventing severe outcomes.

Typical treatment steps include:

• Antibiotics such as ampicillin, often given through an IV
• Hospital care for severe symptoms, particularly in pregnant individuals or those with compromised immunity
• Monitoring for complications like meningitis or bloodstream infections

Mild cases may resolve on their own, but medical attention is strongly recommended for anyone in a high-risk group or with concerning symptoms.

How to Prevent Listeria

The best way to prevent listeria infection is through safe food handling and making informed food choices.

Food Safety Tips:

• Avoid unpasteurized milk and cheeses
• Heat deli meats and hot dogs until steaming
• Wash raw vegetables and fruits thoroughly
• Keep your refrigerator below 40°F
• Clean kitchen surfaces, cutting boards and hands regularly
• Avoid raw sprouts and smoked seafood if you're pregnant or immunocompromised

When listeria outbreaks happen, it's usually linked to specific food products. Stay updated by checking FDA or CDC food recall alerts.

If you have symptoms of listeria infection, especially if you're pregnant, over age 65, or have a weakened immune system, contact your health care provider right away. Early care can make a big difference.

At Riverside Health, we're dedicated to compassionate, collaborative care. We provide a wide range of services, from childbirth to end-of-life care, delivering over 2 million services each year. Our integrated network allows us to support you seamlessly through health, illness, recovery, and wellness. With top clinicians and advanced technology, we’re here for you at convenient locations close to home and work. Visit riversideonline.com.

If you’re wondering where the best place is to get care, please see our guide below:

If your problem is life- or limb-threatening, call 911 or go to the emergency room.

Primary Care – Schedule through MyChart or call your provider’s office who you go to for most health care needs.

Virtual Clinic – Schedule through MyChart or click Here to learn more about Primary Care On Demand.

MD Express Urgent Care – Click Here to find a location near you for after-hours care or when your primary care provider is not available. Open 9am-9pm, Mon-Sun.

If you’re not sure, call Riverside Nurse 24/7 at 1-800-675-6368