Listeria Infection

1 What is Listeria Infection?

Listeriosis (Listeria monocytogenes infection) is a disease mainly caused by gram-positive bacteria that penetrates and replicates inside human cells.

The symptoms of listeria include:

Some people may develop more severe symptoms such as meningitis, mental changes, and swelling in the brain, which may cause death.

2 Symptoms

The symptoms of listeria infection may appear few days or few months after the consumption of contaminated food. Persons with listeriosis can experience fever, nausea or diarrhea.

In case the bacteria affects the nervous system, the symptoms and signs may include:

  • Headache
  • Stiff neck
  • Confusion or changes in alertness
  • Loss of balance
  • Convulsions

A pregnant lady may experience mild symptoms but the baby will be more exposed to this disease and may lead to the death of the unborn or can develop life-threatening infections within a few days.

The signs and symptoms in newborn may include:

3 Causes

Listeriosis occurs due to an outbreak of listeria in contaminated food or fluid. Pregnant women, newborns, cancer patients, AIDS patients, people with diabetes, and alcoholics are at a higher risk for getting the disease. Diagnosis is determined while the listeria bacterium is isolated from the patient's blood and cerebrospinal fluid. Many people who suffer from it experience depression caused by a suppressed immune response.

Most people who have the infection do not require treatment, but those with risk factors may need antibiotics.

People may contract listeria if they swallow contaminated food or fluid. Foods not properly cooked and fluids not treated or pasteurized are breeding grounds for the bacteria.

Pregnant women can transmit listeria organisms to their fetuses or newborns. However, listeriosis is not contagious and is not transmitted from person to person except in the case of pregnancy. The disease enters the human body mainly through ingesting contaminated foods or fluids.

Cooking foods thoroughly, using pasteurized fluids, and avoiding the consumption of food and fluids contaminated with animal or human waste can prevent the infection.

Government agencies make sure foods and fluids are safe for people to consume by instituting regulations to ensure contaminated products are either reported or removed from the market. This sometimes requires production and sales of suspected foods to be completely stopped until proper safety standards are met.

Listeriosis is mainly caused by a gram stain-positive motile bacterium called listeria monocytogenes. During the infection, a person may experience fever, body pains, diarrhea, headaches, and, in more serious cases, meningitis and convulsions. Most of the time, the infection is not severe and displays few or no symptoms, but for other people, especially the elderly, pregnant women, newborns, and people with a compromised immune system, the disease can be life-threatening. 

The listeria bacteria are widespread and are mostly associated with animals on farms. Many animals are uninfected carriers, but humans spread these organisms through bowel flora.

Listeria has been infecting humans for centuries. It was first isolated in 1918 from an infected WWI soldier and was known under many names until 1940, when the genus and species were firmly established. The connection between the bacteria and food-borne illness was not recognized until 1979. A 2010 study determined that the species listeria ivanovii, which was thought to only infect cattle, could infect humans as well.

4 Making a Diagnosis

Making a diagnosis of listeria infection is done by performing several tests.

One should consult a doctor if he/she experiences fever, nausea, diarrhea, or any other mentioned symptom.

The doctor will inquire about your condition in detail so, before visiting the doctor one should pen down the important information like:

  • The symptoms experienced and the time when they first appeared.
  • If you are pregnant.
  • If any kind of other medical condition.
  • Any medication or supplement you are taking.
  • The list of food items you had.

If the doctor suspects listeria infection, he will suggest you to go for a blood and urine test.

5 Treatment

Most listeria infections can be cleared without treatment in about seven days, if the patient is healthy. But those who are at risk require immediate attention, usually in the form of IV antibiotics, which can help reduce the risk. In general, this longer antibiotic treatment lasts three to four weeks.

6 Prevention

The preventive measure that can be followed for listeria infection may include:

  • Keeping the things clean.
  • Washing hands thoroughly before handling or preparing food or after cooking.
  • Scrub raw vegetables while washing.
  • Using a food thermometer to check the quality of food, like in the case of meat, poultry and egg.
  • If you are pregnant or have a weak immune system, avoid eating soft cheese and Mexican-style cheese.
  • One can also avoid consuming hot dogs, luncheon meats, and deli meats.
  • Don't eat refrigerated pates or meat spreads.

7 Risks and Complications

The risk factors for contracting listeria are:

  • Consuming foods and liquids contaminated with listeria bacteria, animal feces, or soil
  • Drinking poorly-treated or unpasteurized liquids

People with damaged immune systems have a higher risk of contracting listeriosis, which can cause further health complications. Others who are considered to be “at risk” include pregnant women, newborns, the elderly, diabetics, cancer patients, those infected with AIDS, those suffering from kidney disease, alcoholics, and patients who have undergone immune-suppression therapy.

Listeria is a food-borne disease; it can only be transferred through direct contact in pregnancies; Otherwise it is not contagious.

Food products associated with listeria outbreaks include soft cheeses, yogurt, seafood, hot dogs, deli meats, fruits, and vegetables.

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