What are the other Names for this Condition? (Also known as/Synonyms)

• Listeria Infection
• Listeria Monocytogenes Infection

What is Listeriosis? (Definition/Background Information)

• Listeriosis is caused by Listeria monocytogenes, a bacterium that commonly resides in the soil and water. It is a foodborne disease that spreads through contaminated raw vegetables, meat, unpasteurized milk and milk products, and certain processed foods
• Although the total number of cases of Listeriosis may be lower than Salmonella or E. coli infections, the rate of death is significantly higher. The bacterium is one of the most deadly and adaptable microbe of those encountered by the healthcare industry
• A significant feature of L. monocytogenes is its ability to survive and grow in low temperatures. Thus, the bacteria can grow in contaminated food items, even in the refrigerator/cold storage
• Generally, healthy individuals are not seriously infected on consumption of contaminated food. However, individuals with compromised immune systems (such as the elderly, HIV/AIDS-infected individuals, and those on immunosuppressant drugs) are at a high risk of serious, life-threatening illness with Listeriosis
• The signs and symptoms of Listeria infection may vary from mild to severe. It could include diarrhea, nausea, fever, and muscle aches. The disease can spread to the heart, lungs, brain, or blood resulting in severe complications
• Generally, pregnant women with Listeria may have mild symptoms. However, they can transmit the infection through the placenta to the fetus, causing life-threatening health issues in the unborn child
• In order to diagnose Listeriosis, a healthcare provider would typically order blood tests. If the disease has spread, urine or spinal fluid tests may be required to evaluate the affected individual
• The potential complications from Listeriosis include septicemia and meningitis. In pregnant woman, the condition may result in miscarriages during early pregnancy. In later stages of pregnancy, the condition may cause stillbirths or potentially fatal health issues
• Individuals with mild Listeriosis may not need any treatment. However, those with serious illnesses need antibiotics therapy. Moreover, pregnant women need prompt attention, to protect the fetus from severe effects of the disease
• Personal hygiene, washing one’s hands before cooking or eating, washing raw vegetables, and cooking meat to high temperatures are some known methods for preventing Listeriosis infection
• The prognosis for Listeriosis is generally unfavorable in newborns and individuals who have a compromised immune system. Normal, healthy individuals recover from the illness without any complications, and the prognosis is excellent

Who gets Listeriosis? (Age and Sex Distribution)

• Listeriosis occurs worldwide and individuals of all ages, races, ethnic groups, and both male and female genders may be affected
• According to the World Health Organization (WHO), most Listeria Infections are reported in the developed nations; many cases of infection might go unreported in the developing nations

What are the Risk Factors for Listeriosis? (Predisposing Factors)

The following groups are at increased risk for contracting Listeriosis:

• Pregnant women: The likelihood of a pregnant woman getting infected with Listeria monocytogenes is reportedly 20 times higher than a normal healthy adult. Also, the unborn and newborn babies have a high risk of infection
• Older individuals (advanced age) have a higher risk for contracting the disease 
• Immunocompromised individuals are highly vulnerable to Listeriosis, and these include:
  • Those with HIV infection or AIDS: Individuals with AIDS are 300 times more likely to contract Listeriosis than healthy people with normal immune system
  • Those with cancer, diabetes, kidney disease, liver disease, and many other conditions
  • Alcoholics
  • Individuals who are under medication for suppressing their immune reactions (such as those who have undergone recent organ transplantation) 

Note: Although healthy adults and children do get infected with L. monocytogenes, the likelihood of serious illnesses in them are low.

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Listeriosis? (Etiology)

Listeriosis is a foodborne disease, caused by the bacterium Listeria monocytogenes. This bacterium is extremely adaptable and can easily exist in the soil, water, and animal feces.

• The bacterium enters the food and food products through contaminated soil, manure, unprocessed dairy, and during handling of unprocessed or processed foods
• Generally, the following foods are more likely to be contaminated by the bacterium:
  • Raw vegetables contaminated through the soil in which they were grown or through fertilizers
  • Unpasteurized milk; dairy products made with unpasteurized milk
  • Meat or milk from animals infected by the bacterium, but the animals did not show any symptom of illness
  • Processed foods, such as soft cheese, cold deli meat cuts, and other products, owing to improper handling post-processing
• Listeria monocytogenes can be transmitted from a pregnant mother to her unborn child through the placenta

What are the Signs and Symptoms of Listeriosis?

The signs and symptoms of Listeriosis can range from mild in healthy adults and children, to severe in immune-compromised individuals. The time between eating contaminated foods and showing signs of infection, can range from a few days to even about 8 weeks.

• Mild symptoms of the infection may include:
  • Gastrointestinal symptoms such as diarrhea
  • Nausea
  • Fever
  • Conjunctivitis
  • Skin lesions and abscesses
  • Muscle aches
• If the infection spreads to internal organs or systems, the symptoms can be severe and may include:
  • Inflammation of the heart (endocarditis)
  • Inflammation of the brain (meningitis)
  • Pneumonia, affecting the lungs
  • If the nervous system is affected, it can result in headaches, gait and balance problems, confusion, convulsions, etc.

The causative bacterium affects pregnant women unusually. Although pregnant women may exhibit only mild symptoms (or be asymptomatic), the likelihood of serious complications in the unborn or newborn baby can be very high.

Babies born with Listeriosis due to infection in the mother, may develop severe complications. The signs and symptoms observed in newborns include:

• Disinterest in feeding
• Fever
• Vomiting
• Crankiness
• Meningitis in late-onset Listeriosis, which a baby develops a few weeks after birth
• Possible long-term neurological damage
• Developmental delays

How is Listeriosis Diagnosed?

In order to diagnosis Listeriosis, a healthcare provider may employ the following tests and exams:

• Complete physical examination and an evaluation of medical history
• Assessment of symptoms
• Blood tests
• When there is a suspicion that the disease has spread to the internal organs, additional tests, such as urine or spinal fluid analysis, may be requested

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Listeriosis?

Potential complications from Listeriosis in vulnerable individuals could include the following:

• Endocarditis (infection in the heart)
• Septicemia
• Meningitis
• Liver and kidney failure
• Pneumonia

In pregnant women, the complications could include:

• Miscarriage
• Pre-term delivery
• Stillbirth

The mortality rate in infants born with Listeriosis is high. Infants who survive the disease may face complications including neurological damage and developmental delays.

How is Listeriosis Treated?

Healthy adults and children with Listeria Monocytogenes Infection may have mild symptoms and may not need any treatment.

• Those with serious symptoms require antibiotics therapy
• Pregnant women need prompt antibiotic treatment to prevent the unborn baby from being infected
• In newborns with Listeriosis, a combination of antibiotics may be required to treat the infection successfully

How can Listeriosis be Prevented?

The following are some known methods for preventing Listeriosis:

• Hand-washing with soap and water before handling food or eating
• Cleaning all utensils and food preparation surfaces with soap and water
• Washing raw vegetables under running water; using a scrub brush may be helpful
• Avoiding unpasteurized milk and dairy products made from it
• Cooking food thoroughly, specifically egg, poultry, and meat: Using a food thermometer to ensure that a safe temperature, to kill the microbes in food has been reached, can be beneficial
• Keeping track of recall notices for foods and eliminating them promptly from the refrigerator, pantry, etc. Discarding foods that were in contact with potentially contaminated foods is also important
• Carefully packaging contaminated items before disposal, so that pets are unable to gain access and contract or spread infection

What is the Prognosis of Listeriosis? (Outcomes/Resolutions)

• In healthy adults or children, Listeriosis generally does not cause much harm and the prognosis is excellent. In individuals with weak or compromised immune system, the prognosis is evaluated on a case-by-case basis and may be unpredictable
• Pregnant women who contract Listeriosis can have severe complications for the baby including miscarriages, stillbirths, and infant fatalities. The mortality rate is reported to be high (about 15%) in infants and the outcome is not considered to be favorable

Additional and Relevant Useful Information for Listeriosis:

Please visit our Infectious Diseases Health Center for more physician-approved health information:

http://www.dovemed.com/diseases-conditions/infection-center/