By: Candess Zona-Mendola

Introduction

When it comes to foodborne illnesses, Listeria is the Komodo Dragon of them; it is rare, but deadly. Little does one know that, although it is considered a rather rare foodborne illness, it is among the leading causes of death in terms of food poisoning.[1] Listeria is responsible for most of the deadly foodborne illness-related outbreaks in the United States in recent history – and considered the cause for the deadliest outbreak of them all involving cantaloupes. Hardy and resilient, this bacterium can live in subzero temperatures and salty environments. The most concerning facts about it involves its hardiness and that is it known for its presence in food-manufacturing plants.[2]

Despite its resilience, it is considered to be rare and possibly declining. Based on the Centers for Disease Control and Prevention survey collected in 1997, Listeria was considered responsible for approximately 2500 illnesses and 500 deaths in the United States prior to 1997.[3]

Statistics with Listeria are very daunting. The Centers for Disease Control and Prevention estimate that about 1600 illnesses and over 260 deaths due to Listeria poisoning occur annually in the United States.[4] In the year 2012, the Centers for Disease Control and Prevention calculated that there were 831 foodborne outbreaks reported involving various different bacteria and pathogens. Of these, four confirmed and one suspected outbreak involved Listeria.[5] The number of outbreaks seems rather small, but when one accounts for the fact that it is the leading cause of death related to foodborne illness – it is downright scary. As it grows well in the seemingly safe environment of our freezers, one often neglects to look out for it in terms of regular food safety practices.

What is Listeria?

For purposes of this essay, we will discuss Listeria monocytogenes. Listeria monocytogenes is a gram-positive bacterium categorized in the Listeria genus. The five other species of Listeria include: Listeria grayi, Listeria innocua. Listeria ivanovii, Listeria seeligeri and Listeria welshimeri. This genus, in all, has 17 species. Listeria monocytogenes has 13 different serotypes, and the serotypes 1/2a, 1/2b, and 4b are linked to the majority of foodborne illnesses.[6] This bacterium is very mobile and looks like the quintessential bacteria one sees in the vast majority of microscope photos with their rod-shaped bodies and flagella (tails). Its hardiness is further expressed by its anaerobic nature – meaning its ability to “breathe” in the absence of oxygen. Once Listeria has reached its stage of ideal environment in the human body, they invade human cells to grow and reproduce inside them, as opposed to other foodborne bacteria that live among human cells.[7]

There are some other interesting biological facts about Listeria. For instance, their flagella are only grown in room temperature environments, not in environments below 37° Celsius. When one observes them under a microscope, they appear rod-like in nature, as mentioned previously. Yet, when smeared onto a presentation slide, they appear rounded. This which makes them easily mistaken for Streptococcus – the bacteria responsible for other common human illnesses, such as strep throat, meningitis, pneumonia, fasciitis, and even pink eye. As this bacteria sometimes arranges itself into short “chains” and has the capacity to grow longer, its appearance can also be mistaken for Corynebacterium – the bacteria responsible for diphtheria.

Where does Listeria come from?

Listeria can be found everywhere – in any type of environment and on any continent in the world. It is predominately found in moist environments like soils, decaying vegetation, water sources (like streams and rivers), sewage, and in infected livestock. As Listeria is found most often in soil and water sources, animals and produce are susceptible to contamination. This means that Listeria can be present in potentially healthy farm animals, like cattle, goats, sheep, etc., and on raw foods, like peppers, cucumbers, melons, etc.

It has also been found to be present in manufactured and processed foods, including juices, milk, cheese, ice cream, and frozen food items. As previously noted, Listeria is unlike other bacteria that cause foodborne illness in that it survives well in cold environments. This is especially concerning as it can live and thrive in food manufacturing plants and even in one’s own refrigerator or freezer. Although most food processing companies possess the proper techniques for pasteurization and have satisfactory preparation practices, contamination can happen between the cooking and packaging processes. The Ministry of Agriculture, Food, and Rural Affairs of Ontario, Canada utilizes the example of hot dogs and deli meats in its Listeria literature. A meat-processing plant produces a ready-to-eat food – such as hot dogs and deli meat – and has properly cooked the food to the specific temperatures for the specific length of time to ensure all harmful bacteria has been eliminated. It is then crucial that the plant follow rigorous sanitization procedures to prevent the now properly cooked items from Listeria contamination before they are placed and sealed in packaging.[8]

Typically, humans become infected with Listeria bacteria through consumption or ingestion of contaminated food and water. Fortunately for us, the Center for Science in the Public Interest has published a list of foods known previously to have caused Listeria outbreaks.[9] This list includes:

o    Infected animal meat – potentially from animals that do not even appear to be sick

o    Unpasteurized or raw milk

o    Rare meat and poultry

o    Products made from unpasteurized or raw milk – soft cheeses (Mexican-style, feta, Brie, Camembert, and blue-veined)

o    Raw fruits and vegetables that are infected from the soil they grow in or manure used to fertilize that soil

o    Processed foods

o    Cold leftovers

o    Raw eggs and raw egg products (homemade ice-cream, mayonnaise, eggnog, Caesar salad dressing, raw cookie dough, and raw cake mix)

o    Unpasteurized fruit juices and ciders

o    Refrigerated pâtés or meat spreads

o    Cold ready-to-eat meats (hot dogs, sausage, ham, bologna, etc.)

o    Cold ready-to-eat seafood products (smoked salmon, etc.)

o    Refrigerated smoked seafood

o    Raw sprouts

A History of the Discovery of Listeria

Listeria, alike to Salmonella, was named after a 19th century pioneering scientist and medical professional in his honor by a supporter of the pioneer’s work. Listeria, initially proposed as Listerella, received its name in 1940 in honor of Joseph Lister, a British surgeon who was the first to utilize anti-septic surgery techniques during his work at Glasgow Royal Infirmary. An avid supporter of pasteurization pioneer Louis Pasteur’s work, Joseph Lister believed that, by sterilizing surgical instruments with carbolic acid and cleaning wounds, infections in patients would decline. Thus, surgery would be safer for the patient. His theory was well-documented and proven, and soon, he was known as the father of modern surgery.[10]

In the 20th century, the 1920’s to be more precise, a young South African bacteriologist named Everitt Murray conducted research on animal bacteria outbreaks in Cambridge, England. In 1926, he and his colleagues discovered a mysterious bacterium had infected and killed six of their experimental rabbits in their laboratory.[11] This was the first documented case of Listeria. Mr. Murray named his findings Bacterium monocytogenes. Though, in 1940 Dr. James Hunter Harvey Pirie changed the name to Listeria in honor of Joseph Lister.[12]

Despite its discovery in 1924 and acceptance as a bacterium that could infect humans in 1952, it was not until 1981 that modern science learned that Listeria could cause foodborne illnesses in human beings. It was during this year that a group of people in Halifax, Nova Scotia, became ill after consumption of coleslaw. The outbreak had 41 reported cases of illness and 18 deaths – most of which were pregnant women and their unborn children. Investigators were able to discover that the bacteria were present on the cabbage used to make the coleslaw. The cabbage had been previously contaminated with sheep manure.”[13] Since this devastating outbreak, agencies and medical practitioners have recognized Listeria as a dangerous and important bacterium to diagnose.

Listeria Poisoning – Listeriosis

The proper medical term for the bacterial disease caused by Listeria bacteria is Listeriosis. Infection occurs through oral consumption and ingestion of Listeria-contaminated food or water. As previously noted, the disease is rather rare in humans, but despite its rarity, the case casualty rate of the disease is 21%.[14] The case fatality rate for those with a severe form of infection may approach 25%.[15] In comparison to Salmonellosis, a foodborne illness caused by Salmonella bacteria, has only a 1% mortality rate.[16] Even though, Listeriosis is considered the third leading cause of death among major pathogens that are food transmitted.[17] Although most cases of Listeriosis are non-outbreak related or relatively sporadic, outbreaks involving Listeriosis do occur regularly.[18]

The majority of Listeria bacteria are decimated by the body’s immune system before infection sets in. Those that escape the immune system’s initial response, however, are those that invade the body’s own cells and begin to replicate. Typically, Listeriosis stays in one’s digestive tract. This is labeled as “non-invasive Listeriosis.” However, Listeria can and may turn invasive and spread to the bloodstream (bacteremia) and central nervous system (meningitis) of its host. Listeriosis can be lethal, especially if it infects newborns and unborn children due to its ability to penetrate the endothelial layer of the placenta.[19]

Who Does Listeriosis Infect?

Anyone can contract Listeriosis. Yet, people who are relatively healthy will rarely, if ever, show any signs or symptoms of a Listeria infection. This is most likely because their immune system rids the body of the bacteria before they have a chance to replicate. However, certain groups of people are more susceptible to Listeriosis and susceptible to Listeriosis and the severe, life threatening illness that results from it. At least 90% of people who get Listeria infections are in this high risk group.[20] Individuals who must be particularly careful include:

  • People who have weakened immune systems, including those with human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS)
  • Pregnant women
  • Unborn babies and newborns
  • Adults older than age 65
  • Young children
  • People undergoing chemotherapy
  • People who have diabetes or kidney disease
  • People who have undergone bone marrow or organ (or other body part) transplants
  • People who take high-doses of prednisone or certain rheumatoid arthritis drugs
  • People who take medications to block rejection of a transplanted organ

For purposes of clarification, let’s examine how Listeriosis affects members of this high risk group.

People with weakened immune systems or taking medications that could weaken their immune system.

As previously mentioned the human immune system typically targets and kills the Listeria bacterium before it ever has a chance to replicate and cause illness. Unfortunately, those with compromised immune systems do not have enough or strong enough antibodies to combat the bacterium from the get-go. As the bacterium replicates in human cells, it develops into an invasive strain which penetrates the human bloodstream, called bacteremia. This is essentially just a generalized infection of the bloodstream. This invasive strain can also infiltrate the body’s central nervous system, causing meningitis. Basically, the bacteria can cause severe inflammation of the membranes and/or fluid surrounding the brain and areas of the spinal column.[21] Both invasions can become fatal.

As adults grow older, their immune systems tend to not be as strong as they were in their youth. Also, changes in their metabolism, organs, and body systems as they grow older make it so that they are more capable of becoming infected with Listeriosis than when they were younger. These changes in their body are perfectly normal. More than half of Listeria-related infections happen in adults over the age of 65 years.[22] As such, older adults are four times more likely to contract Listeriosis than a health member of the general population.[23]

Pregnant Women, Fetuses, and Newborns

Pregnant women are highly susceptible to Listeria infection, even though it is a relatively mild illness, like the flu, for the pregnant woman herself. In fact, a pregnant woman is 10 times more likely than a member of the general population to get Listeriosis,[24] and a Hispanic pregnant woman is 24 times more likely to become infected.[25] About one in seven (14%) cases of Listeria infection occurs during pregnancy.[26] It is the complications for the unborn child that are the most concerning, and could include:

  • Miscarriage
  • Stillbirth
  • Spontaneous abortion
  • Preterm labor
  • Premature birth
  • Neonatal sepsis
  • Neonatal meningitis
  • Fatal infection after birth

It is important to note that, as Listeriosis may take a significant amount of time to express symptoms, it is best to be vigilant with newborn babies if it is an iota of suspicion that the mother may have come into contact with Listeria compromised food. Some women never even discover they have been infected with Listeriosis until they have delivered an infected baby or have already lost the baby.

Babies

Much like what was mentioned above with fetuses and newborns, babies could also potentially become ill with Listeriosis. Babies can be affected by Listeriosis from the ingestion of unpasteurized milk products (raw milk).

Signs and Symptoms: How do I know if I have Listeriosis?

Listeria is found regularly in the environment and many people are exposed to it.[27] The best way to determine if one has contracted Listeriosis is to obtain a diagnosis from a medical physician. It is important to note that the onset of Listeriosis takes a while – usually between 3 and 70 days. As the incubation time is pretty long, many people may be infected and not know they have it. Some tend to write-off their symptoms as merely the flu virus.

While waiting for an appointment or have any suspect that illness may have set in, here is some information that may be beneficial.

Generalized symptoms of Listeriosis are relatively mild in healthy individuals. As Listeriosis can present itself is different ways depending on the person, some people may have many or few symptoms. In fact, most healthy people may never have symptoms. For those who exhibit generalized symptoms, these could include, in no particular order:

  • Fever and chills
  • Headache
  • Upset Stomach
  • Abdominal pain
  • Nausea
  • Vomiting
  • Muscle aches
  • Diarrhea or acute febrile gastroenteritis

Again, most people will not exhibit symptoms at all. Most pregnant women may only experience a fever and other mild symptoms like fatigue and aches. Babies born to infected mothers will show symptoms of vomiting, irritability, fever, and little interest in feeding.

However, Listeriosis can spread to the bloodstream and nervous system. This is proof that the bacteria have become invasive and thus, a severe infection. These more serious signs and symptoms, these could include, in no particular order:

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

It is highly recommended that if one has eaten a food that has been recently recalled due to a potential for Listeria contamination or think that they may be ill with Listeriosis and are showing any signs or symptoms noted above, they should seek immediate medical attention. It is crucial to pay attention to any signs and symptoms of possible Listeria infection. If one is exhibiting signs and symptoms mention above in the more severe range, including high fever, severe headache, stiff neck, confusion or sensitivity to light, then those individuals should seek emergency care, as the infection could be lethal.

Usually, mild symptoms could last anywhere from a few days to a couple of weeks.

How is Listeriosis Diagnosed and Treated?

 The first idea to keep in the back of one’s mind is that, if one is not showing signs or symptoms of Listeriosis as mentioned above, one need not panic. It is recommended that if one has eaten food, or suspect that one has eaten food, that has been recalled because of a potential for Listeria contamination, one should wait to see a physician until signs or symptoms show – if any.[28] Again, nearly everyone is regularly exposed to Listeria. The Centers for Disease Control and Prevention note that there is “no clinical value in performing laboratory testing on asymptomatic patients, even if higher risk.”[29] A physician will typically examine the patient for signs and symptoms and may order a blood, urine, stool, amniotic fluid, placenta (in pregnant women), or spinal fluid test to determine if an infection has occurred. The Centers for Disease Control and Prevention noted that a stool culture has not been evaluated as a viable screening tool to diagnose Listeriosis.[30]

Therefore, it is recommended that one heed the medical advice of their physician to allow them to render their proper diagnosis. If one is extremely symptomatic with a fever or stiff neck or is pregnant while showing any symptoms, immediate consultation by a physician is recommended. Immediate treatment could prevent the spread of infection to the body and possibly a fetus in pregnant women.

Diagnosis

If one is not expressing symptoms of Listeriosis, but are concerned they may become sick, one can create a list in case they start to show signs and symptoms. The answers to the questions on this list may be helpful to one’s physician in rendering their diagnosis. These questions are:

  • What are your symptoms and when did they start?
  • Are you pregnant? If so, how far along are you?
  • Are you being treated for any other medical conditions?
  • What medications and supplements do you take?

The Mayo Clinic, in its online Listeria literature, recommends that one write a food diary that lists all of the foods they have eaten each day for as far back as they can remember, especially if they believe they may have ingested a food that has been subjected to a recall.[31] A physician may ask if one has consumed a food implicated in a recall, soft cheese, raw milk, processed meats, or other known culprits of Listeria infections and outbreaks.

Treatment

A non-pregnant healthy person showing no signs or symptoms of infections usually does not need treatment. Those with only mild symptoms may also not need treatment above and beyond over-the-counter medications and/or general supportive care, including rest and increasing one’s water intake.

If one is pregnant or showing more severe signs and symptoms of infection, antibiotics are usually provided to the patient. Babies typically receive the same type of antibiotics as adults who have Listeriosis and possibly a combination of antibiotics depending on the provider’s discretion. For the most severe cases, the patient would be admitted into the hospital and receive, via intravenous delivery, an antibiotic. This decision is usually at the physician’s discretion and depends on a variety of factors – including severity of symptoms, the overall health of the patient, results of testing, and/or other potential risk factors that may not be covered in this essay. Patients receive a variety of medications from over-the-counter anti-diarrheal medications, to mild antibiotics such as: amoxicillin or penicillin, stronger antibiotics such as fluoroquinolones, and possibly Gentamicin in patients with known compromised immune systems.

It is important to note, although extremely rare and even with prompt treatment, Listeriosis could result in death. These cases, however, are more likely to occur in people that are in the high risk group.

Prevention

Despite all of the concerning information provided above, there is good news. Listeria can be combatted and infection can be prevented. As with the prevention of other foodborne illnesses, one should always follow correct food safety practices and good hygienic habits. Those included in the high risk group may also want to avoid consumption of foods known to be included in Listeria outbreaks. These best practices and methods to keep one’s family and themselves safe are noted below.

Food Safety Practices

Food safety practices are simple and effective ways to keep everyone healthy. The Partnership for Food Safety Education, in correlation with the Centers for Disease Control and Prevention, the United States Department of Agriculture, and the Food and Drug Administration, has created an easy-to-remember method to fight foodborne bacteria. Their campaign, “Fight Bacteria — Fight BAC!®” is useful for everyone, and is as follows: [32]

  1. Clean: One should always wash their hands before, during, and after food preparation. Wash hands especially after handling raw meat before moving on to preparing other foods. All one needs is 20 seconds, some soap, and some warm running water.[33]

One should also wash all food preparation surfaces, including countertops, the stove, microwave, oven, etc. Remember, Listeria could also live in a refrigerator or freezer because it can grow in cold environments. It is a good idea to wash these surfaces as well. Even though it is a good practice to clean these surfaces often, it is a good idea to clean up any spills or leaks immediately to prevent cross contamination.

It is a smart practice to also thoroughly rinse any raw produce prior to eating. This is even important if the intention is to cut or peel the produce. The Food and Drug Administration further recommends that firm produce, such as melons and cucumbers, be scrubbed with a produce brush and dried with a clean cloth.[34]

One should not wash meat, poultry or eggs, as it could cause contamination of other surfaces.[35]

  1. Separate: Raw meat and other raw food items should be separated from each other during the cooking preparation. Oftentimes, one may find it especially helpful to have color-coded cutting boards or kitchen items to prevent the cross-contamination of ready-to-eat foods or foods that are not being cooked.

One should also ensure raw meat, poultry, or fish are bagged separately from other food items.[36]

  1. Cook: Listeria is primarily killed through cooking and pasteurization practices.[37] It is important to combat Listeria, and other foodborne illnesses, by always cooking food to the optimum internal temperature to avoid getting sick. Optimum temperatures are:[38]

o    All poultry, including ground: 165° Fahrenheit

o    Ground beef, pork, lamb, and veal: 160° Fahrenheit

o    Beef, and veal chops, roasts and steaks: 145 Fahrenheit

o    Fish: 145° Fahrenheit

A food thermometer is highly recommended as a useful method to ensure food has been properly cooked. Merely checking food for the absence of pink coloring is not sufficient.[39]

  1. Chill: As with all food safety recommendations, one’s refrigerator should be set to 40° Fahrenheit or lower and the freezer set to 0° Fahrenheit or lower. It is an excellent practice to use a refrigerator and freezer thermometer if the unit does not already have one.

Also, food that has just been cooked should be refrigerated within two hours after cooking, and in hot temperatures, over 90° Fahrenheit, should be stored within one hour[40]. Ready-to-eat foods should be eaten as soon as possible and only minimally stored in a refrigerator. Cut melon should be promptly consumed or refrigerated. Any melon left at room temperature for over four hours should be discarded.[41]

            Prevention Methods for Those in the High Risk Group

Those who belong to the high risk group mentioned earlier in this essay can take additional precautions to prevent infection by Listeria bacteria. These precautions include shopping smart, reading food labels, and adhering to food storage guidelines, as follows:

  • Any diary product that has been properly processed will have a “loud and proud” label stating it was “made with pasteurized milk” or that the item has undergone pasteurization.
  • Perishable and ready-to-eat items should be consumed as soon as possible, and if refrigerated, should be consumed within 2-3 days.
  • Adhere to the “best by”, “sell by” or “use by” dates contained on the label of the food product.
  • When in doubt, throw it out.[42] If one suspects something may be contaminated, past its expiration, or does not look right, do not eat it. Even if it looks and smells alright, it could cause illness.
  • One should also follow the United States Department of Agriculture and Centers for Disease Control and Prevention refrigerator storage time guidelines:[43]
    • “Hot Dogs – store opened package no longer than 1 week and unopened package no longer than 2 weeks in the refrigerator.
    • Luncheon and Deli Meat – store factory-sealed, unopened package no longer than 2 weeks. Store opened packages and meat sliced at a local deli no longer than 3 to 5 days in the refrigerator.”
    • Leftovers should be eaten within three to four days.

One can also help prevent infection by avoiding foods that are known to be part of Listeria outbreaks. These foods include:

  • o Raw or unpasteurized milk and its products.
  • o Soft cheesed such as: Feta, queso blanco, queso fresco, Brie, Camembert cheeses, blue-veined cheeses, and Panela unless it is labeled as made with pasteurized milk.
  • o Cold hot dogs, cold cuts, or deli meats. If consumption is desired, these foods should be heated to optimum temperature prior to consumption.
  • o Refrigerated pâté, meat spreads, or smoked seafood.
  • o Store-made salads such as: ham salad, chicken salad, egg salad, tuna salad, or seafood salad.
  • o Store prepared pre-sliced produce.

Canned and shelf stable tuna, salmon, and other fish products are safe to eat.[44]

By heeding these best practices, together we can all eradicate foodborne illness and spread of infection.

Highlights of Some Modern Listeria Outbreaks

There have been several prominent and deadly Listeria outbreaks in modern history. For the purposes of this essay, the focus shall be on outbreaks primarily located within the United States. The basic definition of an outbreak, according to FoodSafety.gov, is “[w]hen two or more people get the same illness from the same contaminated food or drink.”[45] The Centers for Disease Control and Prevention has created an online database, named the Foodborne Outbreak Online Database (FOOD), to track and report outbreaks of foodborne illness by state.

Less than four years after the 1981 Halifax, Nova Scotia outbreak, another devastating Listeria outbreak emerged. Between January 1, and June 14, 1985, the Centers for Disease Control and Prevention received reports of 86 cases involving Listeria poisoning in California – 58 of these cases involved mother-infant pairs.[46] Of the reported cases, there were 29 deaths, which included 8 fetuses, 13 stillbirths, and 8 babies. The governmental investigators were able to trace the infection to Mexican-style soft cheese (queso fresco and cotija) under the Jalisco Products, Inc. brand. The Guadalajara, Jimenez, and LaVaquita brands were also implicated during investigation as their cheese had been manufactured in Jalisco’s plant.[47]

More recently, in 2011, in what is now known as the deadliest United States foodborne illness outbreak, there was a massive Listeria outbreak as a result of contaminated cantaloupes. The Centers for Disease Control and Prevention received reports of 147 illnesses, 33 deaths, and one miscarriage that occurred in about 28 different states in the United States.[48] The investigations by government agencies were able to implicate a single family farm, named Jensen Farms. Under the advisement of the PulseNet system, a national database, investigators were able to compare DNA of bacteria from various reports across the nation to quickly piece together the outbreak. The quick findings allowed investigators to find the source of the problem and potentially save lives. As a further result, the Food and Drug Administration was able to find missing links and procedures in the Jensen Farms food safety practices to hopefully prevent this atrocity from every happening again.

Their hopes were sadly short-lived. There have been approximately 11 additional Listeria outbreaks since 2011 – ranging from contamination of raw milk, soft cheeses, ice cream, caramel apples, sprouts, packaged salads, and most recently frozen produce.

The United States, at the time of this essay, is currently experiencing a major Listeria outbreak involving frozen fruit and vegetables. Investigations are underway to determine what the root of the contamination is, but it has been reported that there are currently eight reports of illness, all of whom have been hospitalized, in three states. Two individuals have died, but it is reported that Listeriosis is not the cause of death.[49] The manufacturer at the base of the outbreak, CRF Frozen Foods of Pasco, Washington, has issued a wide scale recall of its products. Furthermore, brands that have utilized CRF Frozen Foods as a third-party supplier have also placed voluntary recalls on their brands and products that are suspected to have originated from the Pasco, Washington plant. This massive recall of products began on April 23, 2016 and as of May 15, 2016 has expanded at least eight times.[50] Again, investigations are currently ongoing and consumers that are concerned about having contaminated products in their possession are encouraged to visit the Food and Drug Administration’s website here to determine if their products are affected by the recalls.

What is the US Government Doing?

Since 1997, there have been 18,211 discovered and reported outbreaks involving foodborne illnesses, with over 350,000 reported illnesses.[51] This staggering number has prompted governmental agencies to work together to create a system to try to target potential outbreaks in hopes of controlling them and preventing further outbreaks from happening.

In 2001, Listeriosis was added to the list of nationally identifiable diseases.[52] The Council of State and Territorial Epidemiologists has recommended that all testing that isolated a strain of Listeria monocytogenes was to be reported and sent to the patient’s state public health department for subtyping.[53] This is where PulseNet comes in. Essentially, once a medical provider has found proof that a patient has contracted Listeriosis, the provider sends a sample to their state public laboratory. This entity then works with the National Molecular Subtyping Network for Foodborne Disease Surveillance. This agency will then map the genome of the bacteria, through a specialized process called Pulsed-field Gel Electrophoresis, in hopes to link it to other strains of its kind.[54] By finding related strains of the same bacteria, governmental agencies may be able to trace the source of the contamination. As every report made to a public health agency undergoes a prompt interview process, governmental officials are able to use that data, as well as the mapped genome of the strain, to decipher what the common link may be. Thus, the origin of the infection is found and immediate notices can be sent to the company and the consumer.

PulseNet, however, is not alone. Since 1996, the Centers for Disease Control and Prevention also operate a Foodborne Diseases Active Surveillance Network (FoodNet) that tracks trends relating to infections and foodborne illnesses.[55] Through this project and National Surveillance of Bacterial Foodborne Illnesses (Enteric Diseases), the Centers for Disease Control and Prevention have listed Listeria as part of its national case-based surveillance – which also monitors other infectious diseases, both foodborne and not.[56] It is projected that these ventures will allow the United States to track outbreaks, analyze crucial data, and help the country understand how and why these outbreaks occur.

Furthermore, since the 2011 Jensen Farms outbreak, the Food and Drug Administration has provided its response to the outbreak by calling for a full implementation of the Food Safety Modernization Act.[57] In fact, then current Senior Advisor for the Food and Drug Administration, Sherri McGarry, publically commented that “[w]e’re going to take these lessons learned, share that with our partners and industries, CDC and the states, and what we want to do is we want to really prevent this from happening in the future.”[58]

President Barack Obama signed the Food Safety Modernization Act (FSMA) on January 4, 2011, and it is now known as “the first major piece of federal legislation addressing food safety since 1938.”[59] The purpose of the Act was to reform the food safety laws of the United States that had been previously in place for over 70 years – and thus, shifting the focus from infection response to prevention.[60] Since its implementation, the Food Safety Modernization Act has implemented training and provided simple resources to food producers, manufacturers, retailers, medical professionals, and consumers to help combat and prevent the spread of foodborne illness.[61]

Conclusion

In conclusion, one can deduct from this essay that Listeria poisoning and infection is preventable. Through the furthering of our own knowledge, to the supporting of governmental intervention into the United States food laws, to something as simple as washing hands, anyone can make a difference.

[1] Food and Drug Administration. Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins. Second Edition. 2012.

[2] Food and Drug Administration. Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins. Second Edition. 2012.

[3] Food and Drug Administration. Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins. Second Edition. 2012.

[4] http://www.cdc.gov/listeria/statistics.html

[5] http://www.cdc.gov/listeria/statistics.html

[6] Food and Drug Administration. Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins. Second Edition. 2012.

[7] Schlech W.F. III; Acheson, D. (2001). “Foodborne listeriosis”. Clin. Infect. Dis. 31 (3): 770–775. doi:10.1086/314008. PMID 11017828.

[8] “Controlling Listeria Contamination in Your Meat Processing Plant”. Government of Ontario. 27 February 2007.

[9] https://www.cspinet.org/foodsafety/brochure_pregnancy.html

[10] Pitt, Dennis; Aubin, Jean-Michel (2012-10-01). “Joseph Lister: father of modern surgery”. Canadian Journal of Surgery 55 (5): E8–E9.

[11] Murray E.G.D., Webb R.E., Swann M.B.R. (1926). “A disease of rabbits characterized by a large mononuclear leucocytosis, caused by a hitherto undescribed bacillus Bacterium monocytogenes (n. sp.)”. J. Pathol. Bacteriol. 29: 407–439.

[12] Harvey P.J.H. (1940). “Listeria: change of name for a genus of bacteria”. Nature 145 (3668): 264.

[13] Schlech WF, Lavigne PM, Bortolussi RA, et al. (January 1983). “Epidemic listeriosis–evidence for transmission by food”. N. Engl. J. Med. 308 (4): 203–6.

[14] http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6222a4.htm

[15] http://www.microbiologyinpictures.com/listeria%20monocytogenes.html

[16] Food and Drug Administration. Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins. Second Edition. 2012.

[17] http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6222a4.htm

[18] Cartwright EJ, Jackson KA, Johnson SD, Graves LM, Silk BJ, Mahon BE. Listeriosis outbreaks and associated food vehicles, United States, 1998–2008. Emerg Infect Dis 2013;19:1–9.

[19] “Todar’s Online Textbook of Bacteriology”. Listeria monocytogenes and Listeriosis. Kenneth Todar University of Wisconsin-Madison Department of Biology. 2003.

[20] http://www.cdc.gov/listeria/risk.html

[21] http://www.musa.org/whatis

[22] Centers for Disease Control and Prevention. Vital signs: listeria illnesses, deaths, and outbreaks – United States, 2009-2011. MMWR Morbidity and mortality weekly report. 2013;62(22):448-52.

[23] Centers for Disease Control and Prevention. Vital signs: listeria illnesses, deaths, and outbreaks – United States, 2009-2011. MMWR Morbidity and mortality weekly report. 2013;62(22):448-52.

[24] Centers for Disease Control and Prevention. Vital signs: listeria illnesses, deaths, and outbreaks – United States, 2009-2011. MMWR Morbidity and mortality weekly report. 2013;62(22):448-52.

[25] http://www2c.cdc.gov/podcasts/player.asp?f=8630146

[26] Centers for Disease Control and Prevention. Vital signs: listeria illnesses, deaths, and outbreaks – United States, 2009-2011. MMWR Morbidity and mortality weekly report. 2013;62(22):448-52.

[27] http://www.cdc.gov/listeria/diagnosis.html

[28] http://www.mayoclinic.org/diseases-conditions/listeria-infection/basics/preparing-for-your-appointment/CON-20031039

[29] http://www.cdc.gov/listeria/diagnosis.html

[30] http://www.cdc.gov/listeria/outbreaks/bagged-salads-01-16/health-professionals.html

[31] http://www.drugs.com/mcd/listeria-infection

[32] http://www.fightbac.org/

[33] http://www.cdc.gov/features/handwashing/

[34] http://www.fda.gov/Food/ResourcesForYou/Consumers/ucm114299.htm

[35] http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/safe-food-handling/washing-food-does-it-promote-food-safety/washing-food

[36] http://www.fda.gov/Food/ResourcesForYou/Consumers/ucm114299.htm

[37] http://www.foodsafety.gov/poisoning/causes/bacteriaviruses/listeria/

[38] http://www.cdc.gov/foodsafety/pdfs/gear-up-for-food-safety-i…

[39] http://www.meatsafety.org/ht/d/sp/i/26030/pid/26030

[40] http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/safe-food-handling/leftovers-and-food-safety/ct_index

[41] http://www.cdc.gov/listeria/prevention.html

[42] http://www.webmd.com/food-recipes/food-poisoning/when-in-doubt-throw-it-out-to-prevent-food-poisoning

[43] http://www.cdc.gov/listeria/prevention.html

[44] http://www.cdc.gov/listeria/prevention.html

[45] http://www.foodsafety.gov/poisoning/responds/

[46] http://www.cdc.gov/mmwr/preview/mmwrhtml/00000562.htm

[47] http://www.cdc.gov/mmwr/preview/mmwrhtml/00000562.htm

[48] http://www.cdc.gov/listeria/outbreaks/cantaloupes-jensen-farms/index.html

[49] http://www.cdc.gov/listeria/outbreaks/frozen-vegetables-05-16/

[50] http://www.cdc.gov/listeria/outbreaks/frozen-vegetables-05-16/

[51] http://wwwn.cdc.gov/foodborneoutbreaks/

[52] http://www.cdc.gov/listeria/surveillance.html

[53] http://www.cdc.gov/listeria/surveillance.html

[54] http://www.cdc.gov/listeria/surveillance.html

[55] http://www.cdc.gov/foodnet/index.html

[56] http://www.cdc.gov/nationalsurveillance/index.html

[57] Christina Caron (September 28, 2011). “CDC: Cantaloupe Listeria Outbreak Deadliest in a Decade”. ABC News.

[58] Christina Caron (September 28, 2011). “CDC: Cantaloupe Listeria Outbreak Deadliest in a Decade”. ABC News.

[59] first major piece of federal legislation addressing food safety since 1938

[60] http://www.fda.gov/Food/GuidanceRegulation/FSMA/

[61] http://www.fda.gov/Food/GuidanceRegulation/FSMA/