Is listeria a bacteria

Questions and Answers | Listeria

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Listeriosis is a serious infection caused by the germ Listeria monocytogenes. People usually become ill with listeriosis after eating contaminated food. The disease primarily affects pregnant women, newborns, older adults, and people with weakened immune systems. It’s rare for people in other groups to get sick with Listeria infection.

Listeriosis is usually a mild illness for pregnant women, but it causes severe disease in the fetus or newborn baby. Some people with Listeria infections, most commonly adults 65 years and older and people with weakened immune systems, develop severe infections of the bloodstream (causing sepsis) or brain (causing meningitis or encephalitis). Listeria infections can sometimes affect other parts of the body, including bones, joints, and sites in the chest and abdomen.

Listeriosis can cause a variety of symptoms, depending on the person and the part of the body affected. Listeria can cause fever and diarrhea similar to other foodborne germs, but this type of Listeria infection is rarely diagnosed. Symptoms in people with invasive listeriosis, meaning the bacteria has spread beyond the gut, depend on whether the person is pregnant.

Pregnant women: Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
People other than pregnant women: Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.

People with invasive listeriosis usually report symptoms starting 1 to 4 weeks after eating food contaminated with Listeria; some people have reported symptoms starting as late as 70 days after exposure or as early as the same day of exposure.

Listeriosis is usually diagnosed when a bacterial culture (a type of laboratory test) grows Listeria monocytogenes from a body tissue or fluid, such as blood, spinal fluid, or the placenta.

Listeriosis is treated with antibiotics.

Listeriosis is usually caused by eating food contaminated with Listeria monocytogenes. If infection occurs during pregnancy, Listeria bacteria can spread through the placenta.

See precautions for people at higher risk of Listeria infection >

You should seek medical care and tell the doctor about eating possibly contaminated food if you have a fever and other symptoms of possible listeriosis, such as fatigue and muscle aches, within two months after eating possibly contaminated food. This is especially important if you are pregnant, age 65 or older, or have a weakened immune system.

If you ate food possibly contaminated with Listeria and do not feel sick, most experts believe you do not need tests or treatment. Talk with your medical provider if you have questions about what to do after eating possibly contaminated food.

Most people with invasive listeriosis require hospital care, and about one in five people with the infection die. When listeriosis occurs during pregnancy, it can cause miscarriage, stillbirth, or newborn death. Listeriosis during pregnancy results in fetal loss in about 20% and newborn death in about 3% of cases.

Every year, about 1,600 people get listeriosis in the United States.

A few outbreaks of listeriosis are identified most years. Even though most cases of listeriosis are not part of recognized outbreaks, outbreak investigations help show which foods are sources of listeriosis.

Search NORS Dashboard for information on foodborne disease outbreaks reported to CDC >

Find out how recent scientific advances help disease detectives find and solve more listeriosis outbreaks >

Federal, state, and local governments are doing the following:

Providing guidance to industry and developing and enforcing regulations, like the Food Safety Modernization Act, to focus food safety efforts on safer production and handling of foods
Tracking Listeria infections to identify opportunities to improve policies and practices, particularly to protect groups of people who are more likely to get sick with listeriosis
Investigating and stopping outbreaks by recalling contaminated foods and warning the public
Applying CDC’s enhanced approach to investigating Listeria infections in all states so disease detectives can rapidly solve outbreaks by:
- DNA fingerprinting the germ to identify outbreaks and contaminated foods, and interviewing people who are sick – quickly and with the same questions – about what they ate >
- Helping health departments get the technology and training for whole genome sequencing and analysis, which will make it possible to find Listeria infections and outbreaks more quickly, and track them to their sources >

Find out how CDC and state and federal partners are using real-time whole genome sequencing to solve Listeria outbreaks and make food safer >

People who are more likely to get a Listeria infection (pregnant women, people 65 years or older, and people with a weakened immune system) and those who prepare food for them can:

Know which foods are risky and avoid these foods >
Avoid drinking raw (unpasteurized) milk or eating soft cheeses made from it >
Be aware that Mexican-style cheeses made from pasteurized milk, such as queso fresco, have caused Listeria infections, likely because they were contaminated during cheese-making > [PDF – 1 page]
Heat deli meats and hot dogs until steaming hot before eating.
Refrigerate leftovers within 2 hours in shallow, covered containers and use within 3-4 days.
Avoid cross-contamination in the refrigerator or other places in the kitchen.
Use a thermometer to make sure your refrigerator is 40°F or lower and your freezer is 0°F or lower.

Everyone can:

Know the risks of food poisoning and follow the Clean, Separate, Cook, Chill guidelines >
Visit www.FoodSafety.gov for the latest information on preventing food poisoning >

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Listeria infection (listeriosis) - Symptoms and causes

Overview

Listeria infection is a foodborne bacterial illness that can be very serious for pregnant women, people older than 65 and people with weakened immune systems. It's most commonly caused by eating improperly processed deli meats and unpasteurized milk products.

Healthy people rarely become ill from listeria infection, but the disease can be fatal to unborn babies, newborns and people with weakened immune systems. Prompt antibiotic treatment can help curb the effects of listeria infection.

Listeria bacteria can survive refrigeration and even freezing. So people who are at higher risk of serious infections should avoid eating the types of food most likely to contain listeria bacteria.

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Symptoms

If you develop a listeria infection, you might have:

Fever
Chills
Muscle aches
Nausea
Diarrhea

Symptoms might begin a few days after you've eaten contaminated food, but it can take 30 days or more before the first signs and symptoms of infection begin.

If the listeria infection spreads to your nervous system, signs and symptoms can include:

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

Symptoms during pregnancy and in newborns

During pregnancy, a listeria infection is likely to cause only mild signs and symptoms in the mother. The consequences for the baby, however, can be devastating — the baby can die in the womb or have a life-threatening infection within a few days of being born.

Signs and symptoms of a listeria infection in a newborn can be subtle, but can include:

Little interest in feeding
Irritability
Fever
Vomiting
Difficulty breathing

When to see a doctor

If you've eaten a food that's been recalled because of a listeria outbreak, watch for signs or symptoms of illness. If you have a fever, muscle aches, nausea or diarrhea, contact your doctor. The same goes for illness after eating a potentially contaminated product, such as foods made with unpasteurized milk or poorly heated hot dogs or deli meats.

If you have a high fever, severe headache, stiff neck, confusion or sensitivity to light, seek emergency care. These signs and symptoms can indicate bacterial meningitis, a life-threatening complication of a listeria infection.

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Causes

Listeria bacteria can be found in soil, water and animal feces. People can get infected by eating the following:

Raw vegetables that have been contaminated from the soil or from contaminated manure used as fertilizer
Contaminated meat
Unpasteurized milk or foods made with unpasteurized milk
Certain processed foods — such as soft cheeses, hot dogs and deli meats that have been contaminated after processing

Unborn babies can contract a listeria infection from the mother.

Risk factors

Pregnant women and people who have weak immune systems are at highest risk of contracting a listeria infection.

Pregnant women and their babies

Pregnant women are much more susceptible to listeria infections than are other healthy adults. Although a listeria infection might cause only a mild illness in pregnant women, consequences for their babies can include:

Miscarriage
Stillbirth
Premature birth
A potentially fatal infection after birth

People who have weak immune systems

This category includes people who:

Are older than 65
Have AIDS
Are receiving chemotherapy
Have diabetes or kidney disease
Take high-dose prednisone or certain rheumatoid arthritis drugs
Take medications to block rejection of a transplanted organ

Complications

Most listeria infections are so mild they can go unnoticed. However, in some cases, a listeria infection can lead to life-threatening complications, including:

Generalized blood infection
Inflammation of the membranes and fluid surrounding the brain (meningitis)

Prevention

To prevent a listeria infection, follow simple food safety guidelines:

Keep things clean. Wash your hands thoroughly with warm, soapy water before and after handling or preparing food. After cooking, use hot, soapy water to wash the utensils, cutting boards and other food preparation surfaces.
Scrub raw vegetables. Clean raw vegetables with a scrub brush or vegetable brush under plenty of running water.
Cook your food thoroughly. Use a food thermometer to make sure your meat, poultry and egg dishes are cooked to a safe temperature.

Precautions for people particularly at risk

If you're pregnant or you have a weak immune system, be particularly cautious about listeria. Take additional precautions with these types of foods:

Soft cheeses and Mexican-style cheeses. Don't eat soft cheeses such, as feta, brie, Camembert or blue cheese, or Mexican-style cheeses such as queso blanco and queso fresco, unless it's clear from the packaging that the product was made using pasteurized milk.
Hot dogs and deli meats. Avoid these unless they're reheated until steaming hot. Keep fluid from hot dog packages away from other foods, utensils and food preparation surfaces. Wash your hands after handling these products.
Meat spreads. Don't eat refrigerated meat spreads. Canned or shelf-stable — meaning they can be safely stored at room temperature — meat spreads are acceptable. Refrigerate after opening.
Smoked seafood. These products can be labeled as nova style, lox, kippered or jerky. It's OK to eat them in cooked dishes. Canned or shelf-stable smoked seafood is acceptable.
Raw or lightly cooked sprouts. Cook sprouts of any kind thoroughly.

By Mayo Clinic Staff

Associated Procedures

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What is Listeria monocytogenes and why is it dangerous?

Listeria monocytogenes is a rod-shaped pathogenic bacterium that can grow in food. Once in the human body, Listeria parasitizes inside the cells, while it can cause irreparable harm to the central nervous system or the brain. Listeriosis poses the greatest danger to pregnant women - due to possible pathology of the fetus, and the elderly, because they often have the most severe forms of the disease - septic and meningoencephalitic. Also, people of all ages with impaired immunity often get sick. Despite the relatively low human morbidity, cases of death in sick people are recorded in 25-30%, and among newborns - even in 70-80%. nine0003

Listeria are widely distributed in the surrounding nature - soil, water, plants, as well as in sewage and excrement of people and animals. Listeria is able to multiply at a temperature of 4-6°C. Therefore, Listeria is able to accumulate when food is stored in home refrigerators, when many other bacteria die or stop multiplying and do not compete for a significant increase in the microbial mass of Listeria. This feature of microbes explains the common name of Listeria as "refrigerator microbe". In this regard, the storage of contaminated food products in refrigerators does not prevent, and often, on the contrary, contributes to listeriosis in humans in the absence of additional processing of such products. Similarly, salting vegetables, dairy, and meat products, which is detrimental to many microbes, promotes the growth of Listeria, which can withstand 6-20% salt concentration. nine0003

The main route of human infection with listeriosis is food; people become infected when they consume various food products that have not undergone heat treatment or are improperly stored (dairy products: cheeses, milk, vegetables and salads, meat and semi-finished meat products, poultry). Soft cheeses, as well as fast food products (“fast food”) — hot dogs, hamburgers, etc., are of increased danger. Listeriosis infection is also possible through contact with sick animals (poultry). When ingested, Listeria causes symptoms of severe food poisoning. Vomiting, nausea, diarrhea - all these signs indicate that the bacteria has entered the human body. After three weeks, the disease may already invade the internal organs and the central nervous system, while a person may experience severe headaches, convulsions, loss of consciousness. nine0003

The Rosselkhoznadzor Administration for the Krasnodar Territory and the Republic of Adygea warns that in order to avoid infection with listeriosis, simple preventive measures should be followed, the main of which is food control:

wash raw vegetables and fruits thoroughly;
store meat and dairy products in the refrigerator at a temperature not exceeding +40C;
Avoid all raw foods: dairy products made from unpasteurized milk (prefer pasteurized cheese), raw fish (sushi, smoked salmon, etc. ), raw seafood, raw meat (carpaccio, tartar meat), or raw eggs; nine0012
cook meat before eating;
When buying, carefully check the expiration dates of the products.

Take care of yourself and your loved ones, do not buy food in places not intended for trade. Do not risk your health, because it is in such places that products that have not passed veterinary control are sold, and no one can guarantee that among these products there is no danger to your health!

Listeria as a causative agent of food poisoning

For many centuries, mankind has known that eating poor-quality products can provoke human poisoning. When microorganisms enter food, toxins accumulate in the latter, which can cause food poisoning.

They are characterized by sudden onset, bouts of nausea and repeated vomiting, diarrhoea, cramping abdominal pain, fever and symptoms of intoxication.

Foodborne infections can be caused by various microorganisms, including Listeria. There are several types of Listeria, but only Listeria monocytogenes causes food poisoning in humans. Listeriosis is a foodborne infection caused by a specific bacterial species, Listeria monocytogenes. nine0003

Where does listeriosis come from? Who is at risk for this disease? And how to prevent it? Galina Vyacheslavovna Safroshina, head of the sector of food microbiology and veterinary and sanitary examination of the testing laboratory of the FGBU "Bryansk MVL", will give us answers to these questions.

— Galina Vyacheslavovna, how does listeriosis occur?

- Listeria monocytogenes is actually everywhere. They can be found in soil, dirty water, the gastrointestinal tract, and animal feces. nine0003

Listeria have a peculiarity: unlike many other pathogens, they thrive at low temperatures. Therefore, they actively multiply, for example, in refrigerators. Listeria has another insidious property: the ability to multiply in salty foods of plant and animal origin. If most microbes die under these conditions, then Listeria can withstand a concentration of table salt up to 6-20%.

Listeria die at boiling temperature, and under the influence of sunlight, the causative agent of the disease will live no more than 15 days. nine0003

The risk of contracting listeriosis increases if you consume:

• raw vegetables and fruits that have not been washed well;

• uncooked meat;

• raw foods that have been stored in the refrigerator for a long time;

• unpasteurized milk;

• Prepared foods such as soft cheese, hot dogs, deli meats, salads that have been contaminated with Listeria (eg from someone else's dirty hands).

— Who is at risk for listeriosis? nine0003

— Most often, pregnant women, newborn children, elderly people over 65 years old, that is, those who have a weakened immune system, face severe complications of the course of listeriosis.

— Galina Vyacheslavovna, is it possible to prevent listeriosis, if so, how?

- Listeriosis can be prevented in the same way as other foodborne infections, namely by following the rules of prevention:

• Wash your hands regularly with warm water and soap. Especially before meals, as well as before and after cooking. nine0003

• If you have cut or otherwise cooked raw foods, wash anything that has come into contact with them in hot water and detergent: cutting boards, knives, plates.

• Wash raw vegetables and fruits thoroughly before eating. It is best to do this with a brush under running water.

• Fry meat, poultry, and bring eggs to full readiness. Listeria die when cooked. If you are at risk, take extra precautions. In particular, avoid unpasteurized milk, soft cheeses, and convenience foods (hot dogs, cold cuts) unless they are heated to steam. nine0003

In Russia, the incidence of listeriosis in recent years has been at the level of single cases (less than 0.05 per 100,000 population), which is 15 times lower than similar indicators in European countries. But doctors take it very seriously. The fact is that in some people the infection spreads to the central nervous system and can provoke a serious complication - bacterial meningitis.