Listeria - Symptoms, Diagnosis, Prevention & Treatment


Dr.Neha Gupta profile Authored by Dr.Neha Gupta on 9 Feb 2015 - 11:52.

Listeria refers to a rare but severe bacterial (Listeria monocytogenes) infection that often spreads through contaminated food like raw and improperly processed meat, unpasteurized milk products, cultivated foods like vegetables, fruits, water, seafood etc. Listeria infection can lead to life threatening consequences, particularly in those with weakened immunity, elderly and pregnant women.

Bacteria may also affect the fetus in the womb via blood stream or during C-section birth. Pregnancy complicated with Listeria infection may result in premature birth, miscarriage, stillbirth, etc.  It has been reported that, almost 1 in 20 people may carry Listeria but remain asymptomatic. While in those with severe symptoms, Listeria infection may lead to death in 20 percent of them, approximately.

Basically, Listeria is believed to be present in the digestive tract of animals including cattle and sheep. The stools of these animals are contaminated with Listeria, which further contaminates the raw food, usually those obtained from soil and water, where the risk of Listeria exposure is higher. The causative pathogen (Listeria monocytogenes) can survive even in freezing temperatures below 5ºC and have the ability to penetrate and multiply in the human cells. L monocytogenes is commonly found in the processed and unprocessed foods of animal and plant origin, especially soft cheeses, delicatessen meats, hot dogs, milk and cold salads.




Symptoms usually develop few weeks (approx. 3 weeks) after the exposure to causative bacteria and may last for few days to few months. Common symptoms of Listeria may include:

  • Diarrhoea (usually develops within  48 hrs of consumption of contaminated food)
  • Fever
  • Body aches
  • Nausea
  • Increased sensitivity to light

Listeria infection may or may not spread to the nervous system, but when it invades, it may produce following typical signs and symptoms:

  • Imbalance
  • Headache
  • Neck pain
  • Lack of alertness and altered co-ordination
  • Continuous shaking of the body (convulsions)
  • Drowsiness

In pregnant women, Listeria infection is a severe and significant infection. The symptoms are likely to be milder  ( fever, myalgias, arthargia, backache, headache) while symptoms in the fetus or newborn may be severe and sometimes life threatening.  Preterm delivery is a common complication. Typical signs and symptoms in newborns diagnosed with Listeria may include:

  • Fever
  • Vomiting
  • Lack of interest in feeding
  • Irritation

When to see a doctor?

Seek immediate medical attention, if:

  • You or your child has eaten food that may be contaminated.
  • Notice any sign or symptom in your child (mentioned above)
  • Experiencing multiple signs and symptoms listed above
  • Symptoms persist longer than seven days.



The diagnosis of Listeria infection may begin with an assessment of patient’s history and physical exam. Further, a definitive diagnosis may involve blood and culture tests.

  • Family history and physical examination
  • Blood tests: It is the most effective test to confirm the infection.
  • Urine/ cerebral spinal fluid test: for signs of Listeria infection.
  • Culture: Serum, amniotic fluid or CSF may be tested on Listeria selective medium to look for traces of the causative bacteria in the body.
  • MRI brain : for features of rhomboencephalitis



Although anyone can get infected with Listeria, the risk is significantly higher in those belonging to following categories:

  • Expecting women and fetus
  • Newborn babies
  • Elderly people (above 65)
  • Being infected with HIV
  • Having been undergone chemotherapy sessions for cancer treatment
  • Underlying chronic diseases like Diabetes, liver diseases and renal diseases (e.g. End stage renal disease (ESKD) or chronic kidney disease (CKD), Thalassemia
  • Taking some specific drugs. E.g.Medications for rheumatoid arthritis, drugs taken to prevent rejection of transplanted organs.
  • Alcoholism

Complications: Usually, Listeria infection is mild (except in unborn babies) and does not cause severe complications. However, in rare cases Listeria infection may lead to:

  • Septicaemia/ bacteremia or blood poisoning (when bacterial infection enters the bloodstream)
  • Meningitis (severe infection causing inflammation of the protective layers around the brain)



Treatment of Listeria infection may differ in individuals, depending upon the severity of the symptoms and individual’s overall health. Where the infection is mild, it may not require any treatment but in severe Listeria cases, antibiotics are used.

Drugs and medications: Variety of antibiotics may be prescribed either as oral medications or via IV. Length of treatment may vary depending upon the severity and the complications. Examples of commonly prescribed medications may include ampicillin, trimethoprim-sulfamethoxazole and so on.

Treating Listeria infection in pregnant women: Antibiotics (IV) may be prescribed to prevent infection spread to the fetus.

Alternative treatments: To treat food poisoning and Listeria infection, following alternative approaches may be helpful:

Charcoal remedy: Activated charcoal in (tablet form) may be consumed to absorb and remove the toxins consumed with food.

Goldenseal (Hydrastiscanadensis):Extract of this herb possesses anti-bacterial properties when consumed every 4 hours may be helpful.

Milk thistle and red clover: Helps remove toxins from the blood.

Garlic: Contains allicin that has anti-bacterial properties, making it effective against Listeria infection.

Diet and food recommendations:

Foods to avoid:

  • Cold and unpacked meats
  • Refrigerated meat
  • Raw salad (fruits and vegetables)
  • Raw seafood
  • Cheese e.g. brie, fetta and ricotta
  • Unpasteurized milk
  • Soft serve ice cream
  • Avoid hot dogs
  • Mexican-style cheeses
  • Meat spreads
  • Refrigerated smoked sea foods

Foods to eat:

  • Prefer eating home cooked foods
  • Freshly cooked sea foods
  • Prefer a hard cheese over soft cheese
  • Use pasteurized dairy products
  • Eat packed frozen ice cream
  • Prefer packed foods  (by manufacturers)



  • Store cooked food in the fridge and use it within a day
  • Make sure that chicken / meat is cooked thoroughly
  • Wash all the fruits and vegetables before use
  • Maintain good hygiene
  • Avoid any contamination from outdoors
  • Keep the fridge clean
  • Keep the cooked and uncooked foods separate and covered.



*Disclaimer This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.