Information provided in this section is in the public domain and is provided by US Food and Drug Administration (FDA);
US Department of Agriculture (USDA), Food Safety and Inspection Service (FSIS); the Centers for Disease Control and Prevention (CDC);
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDKD); and Canadian Food Inspection Agency (CFIA).

Bacteria are the largest group
of problematic foodborne pathogens.

Bacteria are small, one-celled microbes that come in many shapes and are capable of reproducing themselves. Typical cell shapes include spherical (cocci), rod-shaped (bacilli), and curved or comma-shaped (spirillar). These shapes can be seen under the microscope when the bacteria are stained in the laboratory with a Gram stain or dye. Whether or not bacterial cells stain Gram-positive (retaining a crystal violet color) or Gram-negative (those losing the color) also aids in identifying what bacteria are present and what treatments to administer.

An important substructure of bacteria is the flagella, a hair-like tail that is responsible for bacterial movement. Bacteria are also classified and identified on the basis of their flagella. Much of modern foodborne microbiology is devoted to keeping pathogenic bacteria out of food products and preventing their growth if they are present. SalmonellaE. coli O157:H7, Listeria, and Shigella are well known species of foodborne bacteria.

2016 CDC/James Archer/Illustrator: Jennifer Oosthuizen

What is Bacillus cereus?

Bacillus cereus (B. cereus) might cause many more cases of foodborne illness than is known. One reason it’s under-reported may be that most people have fairly mild, brief symptoms, so they don’t seek medical attention. But it can cause serious illness in some people, as described below.

Often called “B. cereus” this bacterium can cause two different types of sickness

  • In the first type, after contaminated food is eaten the bacteria make a toxic substance in the small intestine. This can lead to diarrhea, cramps, and sometimes, nausea (but usually not vomiting). Many kinds of contaminated foods have been linked to this illness.
  • The second type occurs if B. cereus makes a different kind of toxin in contaminated food. It causes nausea and vomiting.

Both kinds of illness generally go away by themselves, but can cause serious complications although rarely in otherwise healthy people. As with all infections, people who have weak immune systems (because they have certain other deseases or take medications that weaken the immune system) are much more likely to suffer serious consequences.

Onset of symptoms

  • Diarrheal type: 6 to 15 hours after consumption of contaminated food.
  • Vomiting type: 0.5 to 6 hours after consumption of contaminated food.

Both types of symptoms usually clear up in about a day.

What are the sources of B. cereus?

A wide variety of foods, including meats, milk, vegetables, and fish, have been associated with the diarrheal-type food poisoning.

The vomiting-type outbreaks generally have been associated with rice products; however, other starchy foods, such as potato, pasta, and cheese products, also have been implicated. Food mixtures, such as sauces, puddings, soups, casseroles, pastries, and salads, frequently have been linked with food-poisoning outbreaks.

Who can get a B. cereus infection?
All people are believed to be susceptible to B. cereus food poisoning.

Preventing Bacillus cereus infection

One of the most important things you can do to protect yourself from infection with B. cereus is to keep your food refrigerated at 40ºF or lower. The reason is that, at higher temperatures, B. cereus can form spores – a survival mode in which they make an inactive form that can exist without nutrition and that develops very tough protection against the outside world – that grow and turn into more B. cereus bacteria.

The more bacteria, the more toxin, and the greater the chance that you’ll get sick.

Cooking may kill the bacteria, but it might not disable the toxin that causes the vomiting type of illness. And don’t stop at refrigeration, because a related Bacillus bacterium can survive and grow at refrigerator temperature.

Add other food‐safety measures/good hygiene, like washing your hands, foods and utensils, and cooking setting; and keep raw and cooked foods separate.

Food and Drug Administration (FDA). Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins. Second Edition. Bacillus cereus, pp.92. 2012.

What is Botulism?

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum and sometimes by strains of Clostridium butyricum and Clostridium baratii.

Foodborne botulism is caused by eating foods that contain the botulinum toxin. All forms of botulism can be fatal and are considered medical emergencies.

About Clostridium botulinum
Clostridium botulinum is the name of a group of bacteria. They can be found in soil. These rod-shaped organisms grow best in low oxygen conditions. The bacteria form spores which allow them to survive in a dormant state until exposed to conditions that can support their growth. There are seven types of botulism toxin designated by the letters A through G; only types A, B, E and F cause illness in humans.

Is foodborne botulism common?
In the United States, an average of 145 cases is reported each year. Of these, approximately 15% are foodborne. Outbreaks of foodborne botulism involving two or more persons occur most years and are usually caused by home-canned foods. Foodborne botulism is a public health emergency because many people can be poisoned by eating contaminated food.

Symptoms of botulism
The classic symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Infants with botulism appear lethargic, feed poorly, are constipated, and have a weak cry and poor muscle tone. These are all symptoms of the muscle paralysis caused by the bacterial toxin. In foodborne botulism, symptoms generally begin 18 to 36 hours after eating a contaminated food, but they can occur as early as 6 hours or as late as 10 days.

How is botulism diagnosed?
Physicians may consider the diagnosis if the patient’s history and physical examination suggest botulism. However, these clues are usually not enough to allow a diagnosis of botulism. Other diseases such as Guillain-Barré syndrome, stroke, and myasthenia gravis can appear similar to botulism, and special tests may be needed to exclude these other conditions. These tests may include a brain scan, spinal fluid examination, nerve conduction test (electromyography, or EMG), and a tensilon test for myasthenia gravis. Tests for botulinum toxin and for bacteria that cause botulism can be performed at some state health department laboratories and at CDC.

Treatment of botulism
The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks or months, plus intensive medical and nursing care. The paralysis slowly improves. Botulism can be treated with an antitoxin which blocks the action of toxin circulating in the blood.

If given before paralysis is complete, antitoxin can prevent worsening and shorten recovery time. Physicians may try to remove contaminated food still in the gut by inducing vomiting or by using enemas. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism. Physicians should immediately report suspected cases of botulism to their state health department.

Photo courtesy of CDC/Dr. Holdeman

Complications associated with botulism
Botulism can result in death due to respiratory failure. However, in the past 50 years the proportion of patients with botulism who die has fallen from about 50% to 3-5%. A patient with severe botulism may require a breathing machine as well as intensive medical and nursing care for several months, and some patients die from infections or other problems related to remaining paralyzed for weeks or months. Patients who survive an episode of botulism poisoning may have fatigue and shortness of breath for years and long-term therapy may be needed to aid recovery.

Preventing botulism
Many cases of botulism are preventable. Foodborne botulism has often been from home-canned foods with low acid content, such as asparagus, green beans, beets and corn and is caused by failure to follow proper canning methods.

However, seemingly unlikely or unusual sources are found every decade, with the common problem of improper handling during manufacture, at retail, or by consumers; some examples are chopped garlic in oil, canned cheese sauce, chile peppers, tomatoes, carrot juice, and baked potatoes wrapped in foil.

Persons who do home canning should follow strict hygienic procedures to reduce contamination of foods, and carefully follow instructions on safe home canning including the use of pressure canners/cookers as recommended through county extension services or from the US Department of Agriculture. Oils infused with garlic or herbs should be refrigerated. Potatoes which have been baked while wrapped in aluminum foil should be kept hot until served or refrigerated.

Because the botulinum toxin is destroyed by high temperatures, persons who eat home-canned foods should consider boiling the food for 10 minutes before eating it to ensure safety.

Honey can contain the bacteria that causes infant botulism so, children less than 12 months old should not be fed honey. Honey is safe for persons 1 year of age and older.

What is Campylobacter?

Campylobacter jejuni is the most common cause of bacterial foodborne illness in the United States. . Most cases of campylobacteriosis are associated with eating raw or undercooked poultry. Outbreaks of Campylobacter are usually associated with unpasteurized milk or contaminated water

How do people get infected with Campylobacter?
Campylobacteriosis is most often associated with eating raw or undercooked poultry or from cross-contamination of other foods by these items. Infants may get the infection by contact with poultry packages in shopping carts.

Most people who get ill with campylobacteriosis get diarrhea, cramping, abdominal pain, and fever within two to five days after exposure to the organism. The diarrhea may be bloody and can be accompanied by nausea and vomiting. The illness typically lasts one week. Some infected persons do not have any symptoms. In persons with compromised immune systems, Campylobacter occasionally spreads to the bloodstream and causes a serious life-threatening infection.

Animals can also be infected, and some people have acquired their infection from contact with the stool of an ill dog or cat. The organism is not usually spread from one person to another, but this can happen if the infected person is producing a large volume of diarrhea.

A very small number of Campylobacter organisms (fewer than 500) can cause illness in humans. Even one drop of juice from raw chicken meat can infect a person. One way to become infected is to cut poultry meat on a cutting board, and then use the unwashed cutting board or utensil to prepare vegetables or other raw or lightly cooked foods. The Campylobacter organisms from the raw meat can thus spread to the other foods.

How does food or water get contaminated with Campylobacter?
Many chicken flocks are infected with Campylobacter but show no signs of illness. Campylobacter can be easily spread from bird to bird through a common water source or through contact with infected feces. When an infected bird is slaughtered, Campylobacter organisms can be transferred from the intestines to the meat. In 2005, Campylobacter was present on 47% of raw chicken breasts tested through the FDA-NARMS Retail Food program. Campylobacter is also present in the giblets, especially the liver.

Unpasteurized milk can become contaminated if the cow has an infection with Campylobacter in her udder or the milk is contaminated with manure. Surface water and mountain streams can become contaminated from infected feces from cows or wild birds. This infection is common in the developing world, and travelers to foreign countries are also at risk for becoming infected with Campylobacter.

How is the infection diagnosed?
Campylobacter infection is diagnosed when a culture of a stool specimen yields the organism.

Treatment of Campylobacter infection
Almost all persons infected with Campylobacter recover without any specific treatment. Patients should drink extra fluids as long as the diarrhea lasts. In more severe cases, antibiotics such as azithromycin or erythromycin can shorten the duration of symptoms if given early in the illness. Your doctor will decide whether antibiotics are necessary.

Preventing Campylobacter infection
Some simple food handling practices can help prevent Campylobacter infections.

  • Wash hands with soap before preparing food.
  • Wash hands with soap after handling raw foods of animal origin and before touching anything else.
  • Wash hands with soap after contact with pet feces.
  • Avoid consuming unpasteurized milk and untreated surface water.
  • Make sure that persons with diarrhea, especially children, wash their hands carefully and frequently with soap to reduce the risk of spreading the infection.
  • Using separate cutting boards for foods of animal origin and other foods prevents cross-contamination.
  • After preparing raw food of animal origin, fully clean all cutting boards, countertops, and utensils with soap and hot water.
  • Cook all poultry products thoroughly. Make sure that the meat is cooked throughout (no longer pink) and any juices run clear. All poultry should be cooked to reach a minimum internal temperature of 165 °F.
  • If you are served undercooked poultry in a restaurant, send it back for further cooking.


2013 CDC/ Antibiotic Resistance Coordination and Strategy Unit/Alissa Eckert - Medical Illustrator

About Campylobacter
Campylobacter organisms are spiral-shaped bacteria that can cause disease in humans and animals. Most human illness is caused by one species, called Campylobacter jejuni, but human illness can also be caused by other species. Campylobacter jejuni grows best at the body temperature of a bird, and seems to be well adapted to birds, who carry it without becoming ill. These bacteria are fragile. They cannot tolerate drying and can be killed by oxygen. They grow only in places with less oxygen than the amount in the atmosphere. Freezing reduces the number of Campylobacter bacteria on raw meat.

How common is Campylobacter?
Campylobacter is one of the most common causes of diarrheal illness in the United States. The vast majority of cases occur as isolated, sporadic events, not as part of recognized outbreaks. Active surveillance through FoodNet indicates that about 13 cases are diagnosed each year for each 100,000 persons in the population. Many more cases go undiagnosed or unreported, and campylobacteriosis is estimated to affect over 2.4 million persons every year, or 0.8% of the population.

Campylobacteriosis occurs much more frequently in the summer months than in the winter. The organism is isolated from infants and young adults more frequently than from persons in other age groups and from males more frequently than females. Although Campylobacter does not commonly cause death, it has been estimated that approximately 124 persons with Campylobacter infections die each year.

Long Term Consequences
Most people who get campylobacteriosis recover completely within two to five days, although sometimes recovery can take up to 10 days.

Rarely, Campylobacter infection results in long-term consequences. Some people develop arthritis. Others may develop a rare disease called Guillain-Barré syndrome that affects the nerves of the body beginning several weeks after the diarrheal illness. This occurs when a person’s immune system is “triggered” to attack the body’s own nerves resulting in paralysis that lasts several weeks and usually requires intensive care. It is estimated that approximately one in every 1,000 reported Campylobacter illnesses leads to Guillain-Barré syndrome. As many as 40% of Guillain-Barré syndrome cases in this country may be triggered by campylobacteriosis.

Campylobacteriosis is not a nationally notifiable disease, although many state health departments do track cases. Physicians who diagnose campylobacteriosis and clinical laboratories that identify this organism should report their findings to the local health department. If many cases occur at the same time, it may mean that many people were exposed to a common contaminated food item or water source which might still be available to infect more people. When outbreaks occur, community education efforts can be directed toward proper food handling techniques, and toward avoiding consumption of raw (not pasteurized) milk.

I was intubated and put on a ventilator, I would remain on life support via a tracheostomy for 3 months. I cannot begin to describe the horror I went through during this time. The pain, isolation within my mind not being able to talk or move, the helplessness, as well as the stress my body was going through. My B/P and heart rate would reach dangerous levels since my autonomic nervous system was affected; I was in trouble.

What is Clostridium perfringens?

One of the most common causes of food poisoning in the United States, Clostridium perfringens (C. perfringens) are bacteria that can be found on raw meat and poultry, in the intestines of animals and humans, and in the environment. Some strains produce a toxin that causes diarrhea. CDC estimates C. perfringens causes nearly 1 million cases of foodborne illness each year in the United States.

What are the sources for C. perfringens?

Beef, poultry, gravies, food left for long periods in steam tables or at room temperature, and time and/or temperature abused foods.

What are the symptoms and how long is the incubation period?

Everyone is at risk for C. perfringens.

People with C. perfringens food poisoning develop diarrhea and abdominal cramps within 6 to 24 hours after eating contaminated food.

The illness usually begins suddenly and lasts for less than 24 hours. In severe cases, symptoms may last for 1-2 weeks.

What to do

People can become dehydrated, so it’s important to drink plenty of fluids. This infection usually does not cause fever or vomiting, and it cannot be passed from one person to another.

How can C. perfringens food poisoning be prevented?

  • Thoroughly cook foods, particularly meat, poultry, and gravies to a safe internal temperature. Use a food thermometer to be sure.
  • Keep food hot after cooking: 140ºF (60ºC) or above and serve meat dishes hot, within 2 hours of cooking.
  • Microwave leftovers thoroughly (to 165ºF or above)
  • Refrigerate leftovers ASAP or within 2 hours of preparation at 40ºF (4.4ºC) or below.
  • Divide large amounts of food, such as roasts or big pots of chili or stew, into shallow containers and refrigerate immediately. It is okay to put hot foods directly into the refrigerator.


2016 CDC/James Archer/Illustrator: Jennifer Oosthuizen

When in doubt, throw it out.

Foods that have dangerous bacteria in them may not taste, smell, or look different. Any food that has been left out too long may be dangerous to eat, even if it looks okay.

What is E. coli? What is STEC?

Escherichia coli (commonly abbreviated as E. coli) are a large and diverse group of Gram-negative, bacilli bacteria that normally live in the intestines of people and animals.

Most E. coli are harmless and actually are an important part of a healthy human intestinal tract.

However, some E. coli are pathogenic, meaning they can cause illness, either diarrhea or illness outside of the intestinal tract. Pathogenic E. coli strains are categorized into pathotypes.

Six pathotypes are associated with diarrhea and collectively are referred to as diarrheagenic E. coli. The types of E. coli that can cause diarrhea can be transmitted through contaminated water or food, or through contact with animals or persons.

How is E. coli O157:H7 spread?
The organism can live in the intestines of healthy cattle. Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Bacteria present on the cow’s udders or on equipment may get into raw milk.

Eating meat, especially ground beef that has not been cooked sufficiently to kill E. coli O157:H7 can cause infection. Contaminated meat looks and smells normal.

Although the number of organisms required to cause disease is not known, it is suspected to be very small. Among other known sources of infection is consumption of sprouts, lettuce, salami, unpasteurized milk and juice, and swimming in or drinking sewage-contaminated water.

Bacteria in diarrheal stools of infected persons can be passed from one person to another if hygiene or hand washing habits are inadequate. This is particularly likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected.

Complications of E. coli O157:H7
Some victims, particularly the very young, can develop a very serious complication, Hemolytic Uremic Syndrome (HUS) which can lead to kidney failure and death. HUS, if it occurs, develops an average seven days after the first symptoms when the diarrhea is improving. HUS can lead to life-long complications. In an older population, Thrombotic Thrombocytopenic Purpura (TTP) may be seen. Neurologic symptoms may also be experienced, as well as pancreatitis, diabetes, and high blood pressure.

Treatment of E. coli O157:H7
Treatment often just consists of supportive care, with close monitoring of kidney (renal) functioning, hemoglobin, and platelet counts. Antibiotics may be contraindicated since studies have shown they may promote the development of HUS. Anti-diarrheal agents may also increase the risk of HUS.

Is E. coli O157:H7 killed by freezing?
Freezing does not destroy these bacteria. E. coli O157:H7 survive refrigerator and freezer temperatures.

Nationally Notifiable

E. coli O157:H7 is nationally notifiable. Physicians and labs should report cases to their state health department and the Centers for Disease Control and Prevention (CDC). E.coli O157:H7 is a potentially deadly bacterium that can cause bloody

diarrhea, dehydration, and in the most severe cases, kidney failure. The very young, seniors and persons with weak immune systems are the most susceptible to foodborne illness.

Food contaminated with E. coli O157:H7 may not look or smell spoiled. Consumption of food contaminated with these bacteria my cause serious and potentially life-threatening illnesses. E. Coli O157:H7 is a potentially deadly bacterium that can cause dehydration, bloody diarrhea and abdominal cramps 2-8 days (3-4 days, on average) after exposure to the organism.

While most people recover within a week, some develop a type of kidney failure called Hemolytic Uremic Syndrome (HUS). This condition can occur among persons of any age but is most common in children under 5-years old and older adults.

Symptoms of HUS may include fever, abdominal pain, pale skin tone, fatigue and irritability, small, unexplained bruises or bleeding from the nose and mouth, decreased urination, and swelling. Persons who experience these symptoms should seek emergency medical care immediately.

Many clinical laboratories do not test for non-O157 Shiga toxin-producing E. coli (STEC), such as STEC O26, O103, O45, O111, O121 or O145 because it is harder to identify. Clinical laboratories typically cannot identify non-O157 STEC. 

What is STEC?

Some kinds of E. coli bacteria cause disease by making a poison called Shiga toxin. The bacteria that make these toxins are called “Shiga toxin-producing” E. coli or STEC  (pronounced ess-tec) for short. The most commonly identified STEC in North America is E. coli O157:H7 – often shortened to E. coli O157 or even just O157. Learn more!

When you hear news reports about outbreaks of “E. coli” infections, they usually are talking about E. coli O157. You might hear these bacteria called verocytotoxic E. coli (VTEC) or enterohemorrhagic E. coli (EHEC); these all refer generally to the same group of bacteria.

In addition to E. coli O157, many other kinds (called serogroups) of STEC cause disease. Other E. coli serogroups in the STEC group, including E. coli O145, are sometimes called “non-O157 STECs.” Currently, there are limited public health surveillance data on the occurrence of non-O157 STECs, including STEC O145; many STEC O145 infections may go undiagnosed or unreported.

Compared with STEC O157 infections, identification of non-O157 STEC infections is more complex. First, clinical laboratories must test stool samples for the presence of Shiga toxins. Then, the positive samples must be sent to public health laboratories to look for non-O157 STEC. Other non-O157 STEC serogroups that

2013 CDC/ Antibiotic Resistance Coordination and Strategy Unit/Alissa Eckert - Medical Illustrator
STEC/Shiga toxin-producing E. coli continued

often cause illness in people in the United States include O26, O111, and O103. Some types of STEC frequently cause severe disease, including bloody diarrhea and hemolytic uremic syndrome (HUS), which is a type of kidney failure.

What are the differences between E. coli O157 and other STEC?
Most of what we know about STEC comes from outbreak investigations and studies of E. coli O157 infection, which was first identified as a pathogen in 1982. The non-O157 STEC are not nearly as well understood, partly because these outbreaks are rarely identified. As a whole, the non-O157 serogroup is less likely to cause severe illness than E. coli O157; however, some non-O157 STEC serogroups can cause the most severe manifestations of STEC illness.

Who gets STEC infections?
People of any age can become infected. Very young children and the elderly are more likely to develop severe illness and hemolytic uremic syndrome (HUS) than others, but even healthy older children and young adults can become seriously ill.

What are the symptoms of STEC infections?
The symptoms of STEC infections vary for each person but often include severe stomach cramps, diarrhea (often bloody), and vomiting. If there is fever, it usually is not very high (less than 101˚F/less than 38.5˚C). Most people get better within 5–7 days. Some infections are very mild, but others are severe or even life-threatening.

What are the complications of STEC infections?
Around 5–10% of those who are diagnosed with STEC infection develop a potentially life-threatening complication known as hemolytic uremic syndrome (HUS). Clues that a person is developing HUS include decreased frequency of urination, feeling very tired, and losing pink color in cheeks and inside the lower eyelids.

Persons with HUS should be hospitalized because their kidneys may stop working and they may develop other serious problems. Most persons with HUS recover within a few weeks, but some suffer permanent damage or die.

How soon do symptoms appear after exposure?
The time between ingesting the STEC bacteria and feeling sick is called the “incubation period.” The incubation period is usually 3-4 days after the exposure, but may be as short as 1 day or as long as 10 days.

The symptoms often begin slowly with mild belly pain or non-bloody diarrhea that worsens over several days. HUS, if it occurs, develops an average 7 days after the first symptoms, when the diarrhea is improving.

Where do STEC come from?
STEC live in the guts of ruminant animals, including cattle, goats, sheep, deer, and elk. The major source for human illnesses is cattle. STEC that cause human illness generally do not make animals sick. Other kinds of animals, including pigs and birds, sometimes pick up STEC from the environment and may spread it.

How are these infections spread?
Infections start when you swallow STEC—in other words, when you get tiny (usually invisible) amounts of human or animal feces in your mouth. Unfortunately, this happens more often than we would like to think about.

Exposures that result in illness include consumption of contaminated food, consumption of unpasteurized (raw) milk, consumption of water that has not been disinfected, contact with cattle, or contact with the feces of infected people.

Some foods are considered to carry such a high risk of infection with E. coli O157 or another germ that health officials recommend that people avoid them completely. These foods include unpasteurized (raw) milk, unpasteurized apple cider, and soft cheeses made from raw milk.

Sometimes the contact is pretty obvious (working with cows at a dairy or changing diapers, for example), but sometimes it is not (like eating an undercooked hamburger or a contaminated piece of lettuce).

People have gotten infected by swallowing lake water while swimming, touching the environment in petting zoos and other animal exhibits, and by eating food prepared by people who did not wash their hands well after using the toilet. Almost everyone has some risk of infection.

What is Listeria?

2016 CDC/James Archer/Illustrator: Jennifer Oosthuizen

Listeriosis is an uncommon but potentially fatal infection usually caused by food contamination.

The bacterium Listeria monocytogenes is what causes foodborne illness, and can cause high fever, severe headache, neck stiffness and nausea. It is an important public health problem in the United States.

Healthy people rarely contract listeriosis. Listeriosis can cause miscarriages and stillbirths, as well as serious and sometimes fatal infections in those with weakened immune systems, such as infants, the elderly, and persons living with HIV or undergoing chemotherapy.

What are the Symptoms of Listeriosis?

A person with listeriosis usually has fever and muscle aches, sometimes preceded by diarrhea or other gastrointestinal symptoms. Almost everyone who is diagnosed with listeriosis has “invasive” infection, in which the bacteria spread beyond the gastrointestinal tract.

Symptoms vary with the infected person:

  • Pregnant women typically experience fever and other non-specific symptoms, such as fatigue and aches.
  • Infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
  • Other persons (who aren’t pregnant), in addition to fever and muscle aches, symptoms can also include headache, stiff neck, confusion, loss of balance, and convulsions.

Manifestations of listeriosis are host-dependent.

Listeriosis can present in different ways depending on the type of infection. In older adults and immune-compromised persons, septicemia and meningitis are the most common clinical presentations. Pregnant women may experience a fever and other non-specific symptoms, such as fatigue and aches, followed by fetal loss or bacteremia and meningitis in their newborns. Immuno-competent persons may experience acute febrile gastroenteritis or no symptoms.

In the United States, an estimated 1,600 persons become seriously ill with listeriosis each year. Of these, 260 die.

How does someone get listeriosis?
You get listeriosis by eating food contaminated with Listeria monocytogenes. Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy. However, healthy persons may consume contaminated foods without becoming ill.

Persons at risk can prevent listeriosis by avoiding certain high-risk foods and by handling and storing food properly.

Who Gets Listeriosis?
• Pregnant women: Pregnant women are about 13 times more likely than the general population to get listeriosis. About one in six (17%) cases of listeriosis occurs during pregnancy.
• Newborn babies: Newborn babies suffer the most serious effects of infection in pregnancy.
• Persons with weakened immune systems from transplants or certain diseases, therapies, or medications.
• Persons with cancer, diabetes, alcoholism, liver or kidney disease.
• Persons with AIDS: They are almost 300 times more likely to get listeriosis than people with healthy immune systems.
• Older adults
• Healthy children and adults occasionally get infected with Listeria, but they rarely become seriously ill.

Most human infections follow consumption of contaminated food. When Listeria bacteria get into a food processing factory, they can live there for years, sometimes contaminating food products.

The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in foods that become contaminated after cooking or processing, such as soft cheeses, processed meats such as hot dogs and deli meat (both products in factory-sealed packages and products sold at deli counters), and smoked seafood. 

Unpasteurized (raw) milk and cheeses and other foods made from unpasteurized milk are particularly likely to contain the bacterium.

Listeria is killed by pasteurization and cooking; however, in some ready-to-eat foods, such as hot dogs and deli meats, contamination may occur after factory cooking but before packaging. Unlike most bacteria, Listeria can grow and multiply in some foods in the refrigerator.

How do I know if I have Listeriosis?
If you develop fever and chills while pregnant or if you are very sick with fever and muscle aches or stiff neck, consult your doctor immediately. A blood or spinal fluid test (to look for the bacteria) will show if you have listeriosis.

How is Listeriosis Treated?
• Listeriosis is treated with antibiotics. A person in a high-risk category who experiences fever and other non-specific symptoms, such as fatigue and aches, within 2 months of eating contaminated food should seek medical care and tell the physician or health care provider about eating the contaminated food.
• If a person has eaten food contaminated with Listeria and does not have any symptoms, most experts believe that no tests or treatment are needed, even for persons at high risk for listeriosis.


Even with prompt treatment, some listeriosis cases result in death. This is particularly likely in older adults and in persons with other serious medical problems.

More information from the CDC:

Recommendations for persons who have a higher risk for listeriosis

Older adults, women who are pregnant, and individuals who are immunocompromised, including transplant recipients, individuals with HIV/AIDS, cancer survivors.

• Do not eat hot dogs, luncheon meats, cold cuts, other deli meats (e.g., bologna), or fermented or dry sausages unless they are heated to an internal temperature of 165°F or until steaming hot just before serving.
• Avoid getting fluid from hot dog and lunch meat packages on other foods, utensils, and food preparation surfaces, and wash hands after handling hot dogs, luncheon meats, and deli meats.
• Pay attention to labels. Do not eat refrigerated pâté or meat spreads from a deli or meat counter or from the refrigerated section of a store. Foods that do not need refrigeration, like canned or shelf-stable pâté and meat spreads, are safe to eat. Refrigerate after opening.

• Do not eat soft cheese such as feta, queso blanco, queso fresco, brie, Camembert, blue-veined, or panela (queso panela) unless it is labeled as made with pasteurized milk.

Make sure the label says, “MADE WITH PASTEURIZED MILK.”

• Do not eat refrigerated smoked seafood, unless it is contained in a cooked dish, such as a casserole, or unless it is a canned or shelf-stable product.
• Refrigerated smoked seafood like salmon, trout, whitefish, cod, tuna, or mackerel, is most often labeled as “nova-style,” “lox,” “kippered,” “smoked,” or “jerky.”
• These fish are typically found in the refrigerator section or sold at seafood and deli counters of grocery stores and delicatessens.
• Canned and shelf stable tuna, salmon, and other fish products are safe to eat.

Three Easy Steps To Help Prevent Listeriosis
The U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and the U.S. Department of Agriculture (USDA) recommend that consumers follow these three easy steps to help prevent listeriosis:

  1. Keep the refrigerator at 40°F (4°C) or below.
  2. Use ready-to-eat, refrigerated foods as soon as possible.
  3. Clean the refrigerator regularly.

It’s All About the Fridge
Keeping the refrigerator at 40°F or below is important because – unlike most foodborne bacteria – Listeria will grow in the refrigerator, and it will grow faster at refrigerator temperatures above 40°F.

And, the longer ready-to-eat, refrigerated foods are stored in the refrigerator, the more time Listeria has to grow. Finally, Listeria can spread from one food to another through spills in the refrigerator.

That’s why keeping the refrigerator clean is also important!

Who’s At Risk
People with weakened immune systems are not able to effectively fight illness, so listeriosis can be particularly serious for at-risk people.

If you’re at risk or if you’re preparing food for someone who’s at risk, read on for the specific things you should know.

→ Here are 3 very specific things you can do to help prevent listeriosis. ←

at the Right Temperature
• Your refrigerator should register at 40°F (4°C) or below and the freezer at 0°F (-18°C).
• Place a refrigerator thermometer in the refrigerator, and check the temperature periodically. Adjust the refrigerator temperature control, if necessary. Place a second thermometer in the freezer.

Ready-to-Eat Foods ASAP!
• Use ready-to-eat, refrigerated foods as soon as possible. The longer they’re stored in the refrigerator, the more chance Listeria has to grow.

the Refrigerator
• Clean your refrigerator regularly.
• Wipe up spills immediately. This is particularly important, so Listeria doesn’t have a place to grow and then spread to other foods.
• Clean the inside walls and shelves with hot water and a mild liquid dish-washing detergent; then rinse. Then dry with a clean cloth or paper towel.

New Studies
New studies show that Listeria can grow over time at refrigerator temperatures above 40°F (4°C). And, the longer ready-to-eat, refrigerated foods are stored in the refrigerator, the more chance Listeria has to grow.

Through food handling and spills, Listeria in refrigerated food can spread to other non-contaminated foods. The good news is – cleaning the refrigerator will often prevent the spread of Listeria.


To reduce your risk for listeriosis, it’s important to use an appliance thermometer made specifically for use in a refrigerator or freezer.

For safety, it is important to verify the temperature of refrigerators and freezers. Refrigerators should maintain a temperature no higher than 40°F (4°C).

Frozen food will hold its top quality for the longest possible time when the freezer maintains 0°F (-18°C). An appliance thermometer can be kept in the refrigerator and freezer to monitor the temperature.

Two are Better than One!
If possible, buy two appliance thermometers – one for your refrigerator and one for your freezer.

  • The refrigerator should register at 40°F (4°C) or below.

Measure the temperature in the refrigerator: Put the thermometer in the middle of the refrigerator. Wait 5 to 8 hours.

If the temperature is greater than 38° to 40°F (3° to 4°C), adjust the refrigerator temperature control to a lower setting. Check again after 5 to 8 hours.

  • The freezer should register at 0°F (-18°C).

Measure the temperature in the freezer: Place the thermometer between frozen food packages. Wait 5 to 8 hours.

What is Salmonella?

Salmonella bacteria are the most frequently reported cause of foodborne illness. 

Salmonella is a gram-negative, rod-shaped bacilli that can cause diarrheal illness in humans. They are passed from the feces of people or animals to other people or other animals. Learn more about this bacteria.

For over 100 years Salmonella germs have been known to cause illness. They were discovered by an American scientist named Daniel E. Salmon, for whom they are named. The Salmonella family includes over 2,300 serotypes of bacteria which are one-celled organisms too small to be seen without a microscope.

Two types, Salmonella Enteritidis and Salmonella Typhimurium, are the most common in the United States and account for half of all human infections.

Food contaminated with Salmonella may not look or smell spoiled. Consumption of food contaminated with these bacteria may cause salmonellosis, a foodborne illness. Many people with salmonellosis recover without treatment and may never see a doctor.

However, Salmonella infections can be life-threatening especially for infants and young children and pregnant women and their unborn babies. Older adults and those with weakened immune systems (individuals living with HIV, cancer, diabetes, kidney disease, or transplant patients) are also at a higher risk for foodborne illness.

Most people experience diarrhea, abdominal cramps, and fever within 6 to 72 hours after the contaminated food was eaten. Additional symptoms may be chills, headache, nausea and vomiting that can last up to seven days.

People with any of the following symptoms should see a health care provider immediately:

  • + Signs of dehydration
  • + Prolonged vomiting that prevents keeping liquids down
  • + Diarrhea for more than 2 days in adults, or more than 24 hours in children
  • + Severe pain in the abdomen or rectum
  • + A fever higher than 101ºF  (38.33ºC)
  • + Stools containing blood or pus
  • + Stools that are black and tarry

Pets with Salmonella infections may be lethargic and have diarrhea or bloody diarrhea, fever, and vomiting. Some pets will have only decreased appetite, fever and abdominal pain.

Infected but otherwise healthy pets can be carriers and infect other animals or humans. If your pet has consumed the recalled product and has these symptoms, please contact your veterinarian.

How Common is Salmonellosis?

Every year, approximately 42,000 cases of salmonellosis are reported in the United States. Because many milder cases are not diagnosed or reported, the actual

2013 CDC/ Antibiotic Resistance Coordination and Strategy Unit/Illustrator: James Archer

number of infections may be twenty-nine or more times greater. 

Determining that Salmonella is the cause of the illness is based on laboratory tests that can identify Salmonella in the stool of an infected person. Once Salmonella has been identified, further testing can determine its specific type.

Children are the most likely to get salmonellosis. The rate of diagnosed infections in children less than five years old is higher than the rate in all other persons. It is estimated that approximately 400 persons die each year with acute salmonellosis. Some strains are antibiotic resistant.

Are there Long-Term Consequences to a Salmonella Infection?

Persons with diarrhea usually recover completely, although it may be several months before their bowel habits are entirely normal.

A small number of persons with Salmonella develop reactive arthritis, which is characterized by joint pain, irritation of the eyes, and painful urination. It can last for months or years, and can lead to chronic arthritis which is difficult to treat.

Antibiotic treatment does not make a difference in whether or not the person develops arthritis. Other complications are aortic aneurysm within three months after infection and ulcerative colitis within one year after infection.

What is Shigella?

Shigellosis is an infectious disease caused by a group of bacteria called Shigella. Most Shigella infections are the result of the bacterium passing from one person to another.

The spread of Shigella from an infected person to others can be stopped by frequent hand washing with soap.

Most people infected with Shigella develop diarrhea, fever, and stomach cramps starting a day or two after they are exposed to the bacteria. The diarrhea is often bloody. Shigellosis usually resolves in 5 to 7 days. Persons with shigellosis in the United States rarely require hospitalization. A severe infection with high fever may be associated with seizures in children less than 2 years old. Some persons who are infected may have no symptoms at all, but may still pass the Shigella bacteria to others.

How do people catch Shigella?
The Shigella bacteria pass from one infected person to the next. Shigella are present in the diarrheal stools of infected persons while they are sick and for up to a week or two afterwards. Most Shigella infections are the result of the bacterium passing from stools or soiled fingers of one person to the mouth of another person. 

Shigella infections may be acquired from eating contaminated food. Contaminated food usually looks and smells normal. Food may become contaminated by infected food handlers who neglect to wash their hands with soap after using the bathroom.

Vegetables can become contaminated if they are harvested from a field with sewage in it. Flies can breed in infected feces and then contaminate food.

Water may become contaminated with Shigella bacteria if sewage runs into it, or if someone with shigellosis swims in or plays with it (especially in splash tables, untreated wading pools, or shallow play fountains used by daycare centers). Shigella infections can then be acquired by drinking, swimming in, or playing with the contaminated water.

Preventing the spread of shigellosis:

  • Wash hands with soap and water thoroughly and frequently, especially after going to the bathroom.
  • Dispose of soiled diapers properly.
  • Disinfect diaper changing areas after using them.
  • Keep children with diarrhea out of child care settings.
  • Supervise hand washing of toddlers and small children after they use the toilet.
  • Do not prepare food for others while ill with diarrhea.
  • Avoid swallowing water from ponds, lakes, or untreated pools.
  • After changing diapers, and before preparing foods or beverages, wash your hands.

Diagnosing Shigella infections
Many different kinds of germs can cause diarrhea, so establishing the cause will help guide treatment. Determining that Shigella is the cause of the illness depends on laboratory tests that identify Shigella in the stools of an infected person. The laboratory can also do special tests to determine which antibiotics, if any, would be best to treat the infection.

Treating Shigella infections
Persons with mild infections usually recover quickly without antibiotic treatment. However, appropriate antibiotic treatment kills Shigella bacteria, and may shorten the illness by a few days.

Some Shigella bacteria have become resistant to antibiotics. This means some antibiotics might not be effective for treatment. Using antibiotics to treat shigellosis can sometimes make the germs more resistant. Therefore, when many persons in a community are affected by shigellosis, antibiotics are sometimes used to treat only the most severe cases.

Antidiarrheal agents such as loperamide (Imodium®) or diphenoxylate with atropine (Lomotil®) can make the illness worse and should be avoided.

About Shigella
Shigella is microscopic living creatures that pass from person to person. Shigella was discovered over 100 years ago by a Japanese scientist named Shiga, for whom they are named.

There are several different kinds of Shigella bacteria: 

  • Shigella sonnei, also known as “Group D” Shigella, accounts for over two-thirds of shigellosis in the United States. 
  • Shigella flexneri, or “Group B” Shigella, accounts for almost all the rest.
  • Other types of Shigella are rare in this country, though they continue to be important causes of disease in the developing world.
  • One type found in the developing world, Shigella dysenteriae type 1, can cause deadly epidemics.

How common is shigellosis?
Every year, about 14,000 cases of shigellosis are reported in the United States. Because many milder cases are not diagnosed or reported, the actual number of infections may be twenty times greater.

2019 CDC/ Antibiotic Resistance Coordination and Strategy Unit/Medical Illustrator: Stephanie Rossow

Shigellosis is particularly common and causes recurrent problems in settings where hygiene is poor and can sometimes sweep through entire communities.

It is more common in summer than winter. Children, especially toddlers aged 2 to 4, are the most likely to get shigellosis. Many cases are related to the spread of illness in child-care settings, and many are the result of the spread of the illness in families with small children.

Long term consequences of shigellosis

Persons with diarrhea usually recover completely, although it may be several months before their bowel habits are entirely normal.

About 2% of persons who are infected with one type of ShigellaShigella flexneri, later develop pains in their joints, irritation of the eyes, and painful urination. This is called post-infectious arthritis. It can last for months or years, and can lead to chronic arthritis. Post-infectious arthritis is caused by a reaction to Shigella infection that happens only in people who are genetically predisposed to it.

Once someone has had shigellosis, they are not likely to get infected with that specific type again for at least several years. However, they can still get infected with other types of Shigella.

What can a person do to prevent this illness?
Currently, there is no vaccine to prevent shigellosis. However, the spread of Shigella from an infected person to other persons can be stopped by frequent and careful hand washing with soap. Frequent and careful hand washing is important among all age groups.


Basic food safety precautions and disinfection of drinking water prevents shigellosis from food and water. However, people with shigellosis should not prepare food or drinks for others until they have been shown to no longer be carrying the Shigella bacterium, or if they have had no diarrhea for at least 2 days.

At swimming beaches, having enough bathrooms and hand washing stations with soap near the swimming area helps keep the water from becoming contaminated.

Informing the public health department about cases of shigellosis is vital. It is important for clinical laboratories to send isolates of Shigella to the City, County or State Public Health Laboratory so the specific type can be determined. If many cases occur at the same time, it may mean that a restaurant, food or water supply has a problem that needs correction by the public health department.

If a number of cases occur in a day-care center, the public health department may need to coordinate efforts to improve hand washing among the staff, children, and their families.

When a community-wide outbreak occurs, a community-wide approach to promote hand washing and basic hygiene among children can stop the outbreak.

Improvements in worker hygiene during vegetable and fruit picking and packing may prevent shigellosis caused by contaminated produce.

2013 CDC/ Antibiotic Resistance Coordination and Strategy Unit/Illustrator: Jennifer Oosthuizen

Preventing staph continued:

• Wash hands and under fingernails vigorously with soap and water before handling and preparing food.
• Do not prepare food if you have a nose or eye infection.
• Do not prepare or serve food for others if you have wounds or skin infections on your hands or wrists.
• Keep kitchens and food-serving areas clean and sanitized.
• If food is to be out longer than two hours, keep hot foods hot (over 140°F) and cold foods cold (40°F or under).
• Store cooked food in a wide, shallow container and refrigerate as soon as possible.

Always remember:

  • Wash your hands for 20 seconds with soap and water before, during, and after preparing food, and before eating.
  • Do not prepare food if you are ill with diarrhea or vomiting.
  • Wear gloves while preparing food if you have wounds or infections on your hands or wrists.

What is MRSA?

MRSA stands for methicillin-resistant Staphylococcus aureus, a type of Staph bacteria that is resistant to several antibiotics.

What is Staphylococcus aureus?

Staphylococcus aureus (Staph) is a common bacterium found on the skin and in the noses of up to 25% of healthy people and animals. 

Staphylococcus aureus is important because it has the ability to make seven different toxins that are frequently responsible for Staph food poisoning. Learn more!

What is staph food poisoning?
Staph food poisoning is a gastrointestinal illness. It is caused by eating foods contaminated with toxins produced by Staphylococcus aureus.

The most common way for food to be contaminated with Staphylococcus is through contact with food workers who carry the bacteria or through contaminated milk and cheeses. 

Staphylococcus is salt tolerant and can grow in salty foods like ham. As the germ multiplies in food, it produces toxins that can cause illness. Staphylococcal toxins are resistant to heat and cannot be destroyed by cooking.

Foods at highest risk of contamination with Staphylococcus aureus and subsequent toxin production are those that are made by hand and require no cooking.

Some examples of foods that have caused staph food poisoning are sliced meat, puddings, some pastries and sandwiches.

What are the symptoms of Staph food poisoning?

  • Staph food poisoning is characterized by a sudden start of nausea, vomiting, and stomach cramps. Most people also have diarrhea.
  • Symptoms usually develop within 30 minutes to 8 hours after eating or drinking an item containing Staph toxin, and last no longer than 1 day. Severe illness is rare.
  • The illness cannot be passed from one person to another.

How do I know if I have staph food poisoning?
Toxin-producing Staphylococcus aureus can be identified in stool or vomit, and toxin can be detected in food items. Diagnosis of staph  food poisoning in an individual is generally based only on the signs and symptoms of the patient.

Testing for the toxin-producing bacteria or the toxin is not usually done in individual patients. Testing is usually reserved for outbreaks involving several persons.

If you think you may have food poisoning, contact your physician.

How should a patient with suspected staph food poisoning be treated?
For most patients, staphylococcal food poisoning will cause a brief illness. The best treatments for these patients are rest, plenty of fluids, and medicines to calm their stomachs.

Highly susceptible patients, such as the young and the elderly, are more likely to have severe illness requiring intravenous therapy and care in a hospital.

Antibiotics are not useful in treating this illness. The toxin is not affected by antibiotics.

Preventing staph foodborne illness
It is important to prevent the contamination of food with Staphylococcus before the toxin can be produced.

What is Vibrio?

Vibrio parahaemolyticus bacterium is in the same family as those that cause cholera. It lives in brackish saltwater and causes gastrointestinal illness in humans. Vibrio naturally inhabits coastal waters in the United States and Canada and is present in higher concentrations during summer. Learn more!

What type of illness is caused by Vibrio?
When ingested, Vibrio causes watery diarrhea often with abdominal cramping, nausea, vomiting, fever and chills. Usually these symptoms occur within 24 hours of ingestion. Illness is usually self-limited and lasts 3 days. Severe disease is rare and occurs more commonly in persons with weakened immune systems.

Vibrio infection
Most people become infected by eating raw or undercooked shellfish, particularly oysters. Less commonly, this organism can cause an infection in the skin when an open wound is exposed to warm seawater.

How is Vibrio infection diagnosed?
Vibrio organisms can be isolated from cultures of stool, wound, or blood. If there is clinical suspicion for infection with this organism, the microbiology laboratory should be notified so that they will perform cultures using this medium. A physician should suspect Vibrio infection if a patient has watery diarrhea and has eaten raw or undercooked seafood, especially oysters.

Treating Vibrio
Treatment is not necessary in most cases of Vibrio infection. There is no evidence that antibiotic treatment decreases the severity or the length of the illness. Patients should drink plenty of liquids to replace fluids lost through diarrhea. In severe or prolonged illnesses, antibiotics such as tetracycline or ciprofloxacin can be used. The choice of antibiotics should be based on antimicrobial susceptibilities of the organism.

How common is infection with Vibrio?
An estimated 4500 cases of Vibrio infection occur each year in the United States. However, the number of cases reported to CDC is much lower because surveillance is complicated by underreporting. To improve our ability to monitor trends, infections caused by V. parahaemolyticus and other Vibrio species became nationally notifiable in 2007. State health departments report cases to CDC, and these reports are summarized annually.

How do oysters get contaminated with Vibrio?
Vibriois a naturally occurring organism commonly found in waters where oysters are cultivated. When the appropriate conditions occur with regard to salt content and temperature, Vibrio thrives.

How is Vibrio infection prevented?
Most infections caused by Vibrio in the United States can be prevented by thoroughly cooking seafood, especially oysters. When an outbreak is traced to an oyster bed, health officials recommend closing the oyster bed until conditions are less favorable for Vibrio.

Timely, voluntary reporting of Vibrio infections to state health departments and to regional offices of the Food and Drug Administration (FDA) will help collaborative efforts to improve investigation of these infections. Regional FDA specialists with expert knowledge about shellfish assist state officials with tracebacks of shellfish. When notified rapidly about cases, officials can sample harvest waters to discover possible sources of infection and may close oyster beds. Ongoing research may help us to predict environmental or other factors that increase the chance that oysters carry Vibrio.

What was meant to be a romantic, relaxing meal to celebrate a special occasion became unforgettable for entirely different reasons when Dona became violently ill from eating oysters contaminated with Vibrio parahaemolyticus.​
2016 CDC/James Archer/Illustrator: Jennifer Oosthuizen

How can I prevent poisoning by
marine toxins?

General guidelines for safe seafood consumption:

  1. Although any person eating fish or shellfish containing toxin or disease-causing bacteria may become ill, persons with weakened immune systems or liver problems should not eat raw seafood because of their higher risk of Vibrio infection.
  2. Keep seafood on ice or refrigerated at less than 38° Fahrenheit to prevent spoilage.

Specific advice for avoiding marine toxin poisoning:

  1. Keep fresh tuna, mackerel, grouper, and mahi mahi refrigerated to prevent development of histamine. Don’t believe that cooking spoiled or toxic seafood will keep you safe. These toxins are not destroyed by cooking.
  2. Do not eat barracuda, especially, those from the Caribbean.
  3. Check with local health officials before collecting shellfish, and look for Health Department advisories about algal blooms, dinoflagellate growth or “redtide” conditions that may be posted at fishing supply stores.
  4. Do not eat finfish or shellfish sold as bait. Bait products do not need to meet the same food safety regulations as seafood for human consumption.

What are marine toxins?
Marine toxins are naturally occurring chemicals that can contaminate certain seafood. The seafood contaminated with these chemicals frequently looks, smells, and tastes normal. When humans eat such seafood, disease can result.

What sort of diseases do marine toxins cause?
The most common diseases caused by marine toxins in United States in order of incidence are scombrotoxic fish poisoning, ciguatera poisoning, paralytic shellfish poisoning, neurotoxic shellfish poisoning and amnesic shellfish poisoning.