Incubation Periods and Symptoms


Common   Pathogens

Incubation PeriodS

Common                          Symptoms

   Bacillus Cereus


1-6 hrs (vomiting)               6-24 hrs (diarrhea)

Nausea and diarrhea. Typically resolves within 24 to 48 hours




2 to 7 days               (usually 3 to 5 days)

Diarrhea (often bloody), abdominal cramps, nausea and headaches. Typically resolves within 1 to 10 days

   C. Botulinum



12 to 72 hrs                 (usually 18 to 36 hrs)

Nausea, vomiting, diarrhea, fatigue, headache, dry mouth, double vision, muscle paralysis, respiratory failure. Duration is variable (days to months).

   C. Perfringins



8 to 22 hrs            (average is 12 hrs)

Diarrhea, abdominal cramps and vomiting; usually no fever. Typically resolves within 1 to 2 days.

   E. coli O157:H7



24+ hrs to 10 days (usually 3 to 4 days)

Diarrhea (often bloody), abdominal cramps and vomiting; usually no fever. HUS may develop in rare cases. Typically resolves within 1 to 8 days (in non-complicated cases)

   Hepatitis A


15 to 50 days        (average is 28 days)

Diarrhea, dark urine, jaundice and flu-like symptoms, including headaches, fever, nausea and abdominal pain. Duration is variable (ranging a few weeks to 3 months).



9-48 hrs                         (for GI symptoms)

2 to 6 weeks                 (for invasive disease)


Fever, muscle aches, nausea, diarrhea; pregnant women may suffer flu-like symptoms and stillbirth; elderly, immune-compromised and infants can develop sepsis and meningitis. Duration is variable.




12 to 72 hrs            (usually 24 to 48 hrs)

Diarrhea, abdominal cramps, vomiting, headaches and fever. Typically resolves within 1 to 3 days.



6 to 72 hrs              (usually 12-36 hrs)

Diarrhea, abdominal cramps, nausea, vomiting and fever. Typically resolves within 4 to 7 days.




24 to 72 hrs             (usually 36 to 48 hrs)

Watery diarrhea, nausea, vomiting, abdominal cramps, chills and fever. Stool may contain blood and mucus. Typically resolves within 4 to 7days.



30 minutes to 8 hrs (usually 2 to 4 hrs)

Diarrhea, abdominal cramps, nausea and vomiting. Typically resolves in 24 to 48 hrs.


Bacillus Cereus Fact Sheet

Bacillus cereus, a commonly occurring pathogen which can survive in remarkably hostile conditions, is typically found in soil. Illness associated with B. cereus can occur when heat-resistant B. cereus endospores survive cooking. If the food is then inadequately refrigerated or held for extended periods at improper temperatures the endospores can germinate and multiply. Once the spores germinate, the vegetative cells can multiply and produce illness causing enterotoxins. B. cereus is known to cause two distinctly different types of food-borne illness.

  • The first type of illness, referred to as the Rapid-onset (Emetic) Vomiting-type, is characterized by nausea and vomiting. The incubation period ranges from 1 to 6 hours. Both the symptomology and incubation period mirror those of Staphylococcus aureus.
  • The second type of illness, generally referred to as the Slow-onset Diarrheal-type, is characterized by diarrhea and abdominal pain. The diarrheal-type illness has an incubation period ranging from 6 to 24 hours. The symptoms include watery diarrhea, abdominal cramps and pain. This type generally mimics the symptoms of Clostridium perfringens.

Regardless of type, symptoms typically persist for less than 24 hours. Generally, gastroenteritis symptoms from B. cereus resolve by themselves. In very rare cases, however, some degree of medical intervention may be required.

The diarrheal-type food poisoning has been associated with a wide variety of foods, including meat and vegetable dishes, sauces, pastas, desserts and dairy products. In turn, the vomiting-type outbreaks have typically been associated with rice products. Other starchy foods such as potato, pasta and cheese have also been implicated. Some outbreaks may ultimately go unreported because of the similarities between B. cereus, Staphylococcus aureus intoxication (B. cereus vomiting-type) and C. perfringens food poisoning (B. cereus diarrheal-type).

B. cereus and B. anthracis may pose a higher risk to those working in food preparation areas and slaughterhouses. While intact tissues and meat from animals are sterile, once slaughtered, the potential for contamination emerges.

The presence of large numbers of B. cereus (greater than 10^6 organisms /g) in a food can be indicative of active growth and proliferation of the organism. Confirmation of B. cereus as the etiologic agent in a food-borne illness outbreak requires, at the very least: (1) isolation of strains of the same serotype from the suspect food and patient; (2) isolation of large numbers of a B. cereus serotype known to cause food-borne illness from the suspect food and patient, and (3) isolation of B. cereus from suspect foods and determining their enterotoxigenicity by serological (diarrheal toxin) or biological (diarrheal and emetic) tests. According to the FDA, the rapid onset time from consumption to symptoms in the emetic form of the disease, coupled with microbiological evidence, is often sufficient to diagnose this type of food poisoning.


Schneider et al., "Preventing Foodborne Illness: Bacillus cereus and Bacillus anthracis ". Florida Cooperative Extension Service, University of Florida. November, 2004.

Bacillus Cereus Images

Campylobacter Fact Sheet

Campylobacter is one of the most common causes of diarrheal illness in the United States. (Campylobacteriosis is the infectious disease caused by bacteria of the genus Campylobacter). The vast majority of cases are caused by one species, called Campylobacter jejuni. Campylobacteriosis occurs much more frequently in the summer months than in the winter. Approximately 13 cases are diagnosed each year for each 100,000 persons in the population, although the actual number of illnesses is likely underreported. Campylobacter infection is diagnosed when a culture of a stool specimen yields the organism.

Most cases of campylobacteriosis are associated with the consumption of raw or undercooked poultry. This is because many chickens carry the pathogen, but show no signs of illness. In 2005, for instance, Campylobacter was present on 47% of raw chicken breasts tested through the FDA-NARMS Retail Food program. In turn, Campylobacter can be spread from bird to bird through a common water source or through contact with infected feces. When an infected bird is slaughtered, it is possible for the Campylobacter organisms to be transferred from the intestines to the meat. Household pets can also become infected, and some people have acquired their infection from contact with the stool of an ill dog or cat. Similarly, 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 relatively small number of Campylobacter organisms can cause illness in humans. Most people who become ill with campylobacteriosis develop diarrhea, cramping, abdominal pain and fever within three to five days after exposure to the organism. The diarrhea may be bloody and can be accompanied by nausea and vomiting. Most people who get campylobacteriosis recover completely within two to five days, although in very rare cases recovery can take up to 10 days. 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 erythromycin or a fluoroquinolone can be used, and can shorten the duration of symptoms if given early in the illness. Your doctor will decide whether antibiotics are necessary. Notably, some infected persons never develop symptoms.

In extremely rare cases, in persons with compromised immune systems, Campylobacter can spread to the bloodstream and cause a serious infection. As a result of this infection, some people may 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. Although Campylobacter does not commonly cause death, it has been estimated that approximately 124 persons with Campylobacter infections die each year.

Fortunately, illnesses can be avoided if food is handled and cooked properly. Some simple food handling practices can help prevent Campylobacter infections.

  • 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;
  • Wash hands with soap before preparing food;
  • Wash hands with soap after handling raw foods of animal origin and before touching anything else;
  • Prevent cross-contamination in the kitchen by using separate cutting boards for foods of animal origin and other foods and by carefully cleaning all cutting boards, countertops, and utensils with soap and hot water after preparing raw food of animal origin;
  • 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;
  • Wash hands with soap after contact with pet feces

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.


Campylobacter Images

Clostridium Botulinum Fact Sheet

Clostridium botulinum is a type of bacteria often found in soil.  Botulism is characterized as a rare paralytic disease caused by a nerve toxin produced by the pathogen.  Although there are different types of botulism, food-borne botulism is caused by ingesting the botulism toxin. The rod-shaped organisms grow best in low-oxygen environments. The bacteria themselves form spores which allow for existence in a dormant state. The bacteria then flourish when they are once again exposed to hospitable growth conditions. This is why food-borne botulism is often associated with low acid content, home-canned foods, such as asparagus, green beans, beets and corn. Though extremely rare, outbreaks of botulism from more unusual sources such as chopped garlic in oil, chili peppers, tomatoes, carrot juice and home-canned or fermented fish do occur.

The classic symptoms of botulism can include double or blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Infants with botulism can appear lethargic, feed poorly, become constipated, cry weakly and exhibit poor muscle tone. These symptoms are indicative of the muscle paralysis caused by the bacterial toxin. If untreated, these symptoms may progress to include paralysis of the arms, legs, trunk and respiratory muscles. In food-borne botulism, symptoms generally begin 18 to 36 hours after ingestion of a contaminated product.  In the United States, an average 145 cases are reported each year. Of these, only a small percentage are associated with the consumption of contaminated foods.

Though symptoms typically resolve within a few weeks, paralysis and respiratory difficulty associated with botulism can require intensive treatment. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism. Given the scientific advancements in the treatment of botulism, only an extremely small percentage of botulism cases will result in death.

Notably, the botulinum toxin becomes unstable if exposed to high temperatures, and is destroyed when offending foods are heated to 176 degrees for ten minutes or longer. 


Clostridium Botulinum Images

Clostridium Perfringens Fact Sheet


Clostridium perfringens (“C. perfringens”) is an anaerobic bacterium that is widely distributed throughout the environment. It also occurs in the intestines of humans and animals. Spores of the organism persist in soil, dust, water and areas subject to human or animal fecal pollution. C. perfringens is classified into 5 types (A–E) on the basis of its ability to produce one or more of the following toxins; alpha, beta, epsilon and iota (α, β, ε, and ι). Enterotoxin (CPE)-producing (cpe+) C. perfringens type A is continuously reported as one of the most common food poisoning agents.

As previously mentioned, C. perfringens poisoning is one of the most common reported food borne illnesses in the United States. Undercooked poultry is the most frequently implicated source. Institutional environments (such as school cafeterias, hospitals, nursing homes, prisons, etc.), where large quantities of food are prepared several hours before serving, are at the highest risk of experiencing a C. perfringens outbreak.

When exposed to extreme conditions, high temperature for example, C. perfringens pathogens can sporulate. These spores can be very resilient. They can, for instance survive at boiling temperature for up to one hour. When the environment once again becomes conducive to growth, the cells return to a vegetative state. Instances, such as when the product is “hot-held” at improper temperatures, improperly cooled or stored, etc, may lead to the production of large numbers of organisms. If the product is subsequently consumed, the pathogens can produce the toxins which result the onset of illness. Temperature abuse is cited as the most common circumstance in which C. perfringens outbreaks occur. The growth range for the bacteria is between 53 and122 degrees fahrenheit, with the optimal range falling being between 109 to 116 degrees.

In a typical outbreak, dozens, or in some cases hundreds of individuals can be affected. It is likely that some outbreaks go unreported because the implicated foods or patient feces are not tested for C. perfringens. The CDC estimates that about 10,000 actual cases occur annually.

Typically, symptoms occur 8 to 22 hours after the ingestion of a large number of organisms, and may include severe abdominal cramps and diarrhea. The illness is usually over within 24 hours, but less severe symptoms may persist in some individuals, particularly the elderly and infirm, for 1 or 2 weeks. A few deaths have been reported as a result of dehydration and other complications.

Diagnosis of C. perfringens poisoning can be made by determination of common symptomology or bacteriological testing. C. perfringens can be subjected to PFGE fingerprinting but is not tracked by PulseNet. Serological assays are used for detecting enterotoxin in the feces of patients and for testing the ability of strains to produce toxin. The procedures take 1-3 days.

Necrotic enteritis (pig-bel syndrome) is a more serious disease that can also be caused by C. perfringens in extremely rare cases.  Deaths from necrotic enteritis, while rare, can result from intestinal infection and necrosis secondary to septicemia.


Berdanier, Carolyn, and Dwyer, Johanna and Feldman, Elaine. Handbook of Food and Nutrition: Second Edition. CRC Press, 2007.

Clostridium Perfringens Images

E. coli O157:H7 Fact Sheet

E. coli (Escherichia coli) is a common bacterial inhabitant of the intestines of all animals, including humans.  It is, in fact, the dominant species of bacteria found in feces, and is known to have hundreds of strains virtually all of which are harmless, or, in some cases, helpful.  Normally, E. coli serves a useful function in the body by suppressing the growth of harmful bacterial species and synthesizing appreciable amounts of vitamins.

E. coli serotype O157:H7 is a rare variety of E. coli that produces toxins which are capable of inflicting damage to the lining of the intestine. These toxins are closely related or identical to the toxin produced by Shigella dysenteriae and are referred to as Shiga toxins. In very rare instances, the infection can progress to hemolytic uremic syndrome ("HUS") and kidney failure. E. coli O157:H7 can survive at low temperatures as well as under acidic conditions, and the infectious dose is relatively small.

Undercooked or raw hamburger (ground beef) has been implicated in many outbreaks of E. coli O157:H7 but, as previously mentioned, raw or undercooked beef is only one of many potential sources. Historically, outbreaks have implicated water, spinach, alfalfa sprouts, unpasteurized fruit juices, dry-cured salami, lettuce, game meat, and cheese curds. E. coli O157:H7 has also been found in sheep, pigs, goats, poultry, and deer. Wild and domestic animals that live around cattle farms may also harbor this species. Some other risk factors include drinking or swimming in contaminated water, handling animal feces and eating fruit and vegetables fertilized or irrigated with animal manure. Poor personal hygiene (e.g., not washing hands properly) and unsafe food preparation practices also increase the risk of contracting or spreading E. coli.

Infection from E. coli O157:H7 is characterized by mild to severe cramping (abdominal pain) and diarrhea which is initially watery but can become bloody. Some individuals exhibit watery diarrhea only.  Occasionally, vomiting occurs. Fever is typically either low-grade or absent. The illness is usually self-limited, and lasts for only a few days.  As noted, in very rare cases, illness may be complicated by HUS or thrombotic thrombocytopenic purpura (TTP). Some individuals, the very young in particular, are more suseptible to serious complications. On the opposite end of the spectrum, some infected individuals remain asymptomatic.

Symptoms usually manifest within 2 to 4 days. Most people recover without specific treatment within days after onset. There is no evidence that antibiotics improve the course of disease.  In fact, it is believed that treatment with some antibiotics may precipitate kidney complications. Anti-diarrheal agents, such as loperamide (Imodium), should be avoided.

There are several microbiological methods that can be used to isolate E. coli O157:H7. Unlike typical E. coli, O157:H7 isolates do not ferment sorbitol and are negative with the MUG assay; therefore, these criteria are commonly used for selective isolation. Sorbitol-MacConkey agar has been used extensively to isolate this organism from clinical specimens. Hemorrhagic colitis agar, a selective and differential medium, is used in a direct plating method to isolate O157:H7 from foods. A third procedure uses a Sorbitol-MacConkey medium containing potassium tellurite and Cefixime. Faster testing methods using a variety of technologies, including recombinant DNA methods, are being developed.

As is the case with all foodborne pathogens, safe handling and preventive measures can eliminate the risk of becoming ill from E. coli O157:H7.  Some key preventative measures include:

In the home:

  • Cook ground beef to at least 165 degrees Fahrenheit or until the meat is brown and the juices run clear;
  • Drink only milk products and fruit juices that have been pasteurized;
  • Wash all fruit and vegetables adequately and carefully;
  • Wash hands with soap after using the restroom;
  • Take special care when handling and disposing of diapers;
  • Wash hands before food preparation;
  • Wash hands immediately after handling raw meat;
  • Take care to clean all kitchen utensils and surfaces after handling raw meat to avoid cross-contamination; and
  • Make sure all drinking water has been properly treated.

On the farm:

  • Use potable quality water for washing fruit and vegetables;
  • Manage fecal waste so as not to contaminate water supplies;
  • Avoid spreading fecal material via clothes and shoes and tools; and
  • Wash hands with soap after petting or handling animals.


Schneider, Keith and Renee M. Goodrich, and Melissa A. Kirby. “Preventing Foodborne Illness: E. coli 0157: H7”. Food Science and Human Nutrition Department, Florida Cooperative Extension Service, IFAS, University of Florida. January, 2003.

Mead, P. S. and P. M. Griffin, 1998: Escherichia coli O157:H7. Lancet 352, 1207-1212.

E. coli O157:H7 Images

E. sakazakii Fact Sheet

Several species within the genus enterobacter have been recognized as causative agents of hospital- acquired infections. Enterobacter sakazakii is a rod-shaped bacterium that has been implicated in several outbreaks of neonatal meningitis. It has been isolated from clinical materials including cerebrospinal fluid, blood, skin, wounds, respiratory tract (sputum, throat, and nose), the digestive tract and urine. Researchers have also isolated E. sakazakii from reconstituted milk-based infant formula. The presence of the microorganism in the finished product, therefore, probably originated in the factory, likely from heat-sensitive micronutrients added post-pasteurization.

E. sakazakii is a rare cause of invasive disease in neonates.  Infection has been known to cause meningitis, which can result in severe neurological complications. Illnesses associated with E. sakazakii, including sepsis, meningitis, or necrotizing enterocolitis, have prompted the recall of certain powdered infant formulas in the United States.

Infant infections in the healthcare setting can be avoided by the proper handling and use of infant formula products. Clinicians should be aware that not all powdered formulas are sterile, and could potentially contain opportunistic pathogens such as E. sakazakii. A recent survey indicated that of 16 responding facilities, nine used powdered formulas in the NICU setting; four (25%) reported powdered formula as a principal source of patient feeding, and five (31%) reported use of powdered formula along with other formula types for principal feeding.

Risk for infection depends upon several factors, including the quantity of bacteria present in the product, handling after preparation, and underlying patient characteristics (e.g., immunosuppression, premature birth, or low birth weight). Because powdered formula is not always sterile, and may provide a good medium for growth, prolonged periods of storage or administration of powdered formula at room temperature might amplify the amount of bacteria already present. Health-care providers can reduce the risk to hospitalized neonates by choosing alternatives to powdered forms when possible.  Individuals preparing formula should in all cases ensure they are following the manufacturer's written instructions.

A study of the thermal resistance of E. sakazakii in reconstituted dried infant formula demonstrated that the organism is highly thermo-tolerant. Thus, process controls during manufacture, along with the use of aseptic procedures during the storage and preparation of dried infant formula, can significantly reduce the potential for illness.

The FDA has already proposed recommendations concerning the preparation of powdered infant formula in the NICU, and advises that formula products be selected on the basis of nutritional need. They also recommend that written guidelines be available in the event of a product recall. These guidelines should include notification of health care providers, a system for reporting and following up on specific formula products used, and retention of recall records.


Centers for Disease Control and Prevention. Enterobacter sakazakii infections associated with the use of powdered infant formula -- Tennessee, 2001. MMWR Morb Mortal Wkly Rep 2002; 51 (14): 298-300.

Weir, Erica. “Powdered infant formula and fatal infection with Enterobacter sakazakii”. Canadian Medical Association Journal, Vol. 166, 2002.

Kanhai et al. “Occurrence of Enterobacter sakazakii in food production environments and households”. Lancet, Vol. 363, 2004.

E. sakazakii Images





Hepatitis A Fact Sheet

Hepatitis A is a contagious liver disease that results from infection with the hepatitis A virus (HAV). It has the potential to range from a mild illness with limited syptomology to a severe illness lasting several months. Hepatitis A is usually spread when a person ingests food contaminated by the virus. Hepatitis A appears only as an acute or newly occurring infection and does not become chronic.

Reported cases of Hepatitis A are at their lowest in 40 years, due in large part, to effective vaccination programs. Doctors now vaccinate children, people traveling abroad and those at heightened risk for the disease. Vaccination with the full, two-dose series of hepatitis A vaccine is the best way to prevent infection. The Hepatitis A vaccine has been licensed in the United States for use in people 12 months and older. The vaccine is recommended for persons who have an increased likelihood of contracting HAV infection or are more likely to get seriously ill if they contract the virus.

In the United States, there were an estimated 32,000 new hepatitis A virus infections in 2006. This estimate is considered to be conservative, however, because many people infected with Hepatitis A remain asymptomatic. In two recent outbreaks, one in 1997 and another in 2003, strawberries and green onions were considered to be the vehicles through which the pathogen was transmitted. Given that the virus is transmitted through fecal–oral contact, good hygiene (including proper hand washing), is integral to the prevention of illness.

Not surprisingly, illnesses associated with Hepatitis A are more likely to occur in countries where Hepatitis A is common, and where there are poor sanitary conditions or poor personal hygiene. The food and drinks most likely to be contaminated include fruits, vegetables, shellfish, ice, and water. In the United States, chlorination of water typically kills virus when present in water.

There is no specific treatment for Hepatitis A. Patients generally suffer from loss of appetite, and the main concern is ensuring that a patient receives adequate nutrition. Young children infected with Hepatitis A commonly remain asymptomatic.  For adults, the most common symptom, occurring in more than 70 percent of cases, is jaundice. Symptoms usually last less than 2 months, although extremely rare cases can experience a prolonged or relapsing illness which can last for up to 6 months. The average incubation period for Hepatitis A is 28 days. The most common symptoms—aside from jaundice—include:

  • Fever;
  • Fatigue;
  • Loss of appetite;
  • Nausea;
  • Vomiting;
  • Abdominal pain;
  • Dark urine;
  • Clay-colored bowel movements; or 
  • Joint pain.

Like other pathogens, illness from Hepatitis A can be easily avoided.  The pathogen is killed after one minute at 185 degrees F (85 degrees C).  Thus, properly boiling contaminated water, or thoroughly cooking contaminated foods, will destroy the virus.


Hepatitis A Images

Listeria Fact Sheet

Listeria monocytogenes is a Gram-positive bacterium, motile by means of flagella. Some studies suggest that 1-10% of humans may be intestinal carriers of L. monocytogenes. It has been found in at least 37 mammalian species, both domestic and feral, as well as at least 17 species of birds and some species of fish.  L. monocytogenes can be isolated from soil, silage, and other environmental sources. The pathogen is also able to resist, in part, the deleterious effects of freezing, drying and heat.

Listeriosis is an infection caused by eating food contaminated with the pathogen. The disease affects primarily persons of advanced age, pregnant women, newborns, and adults with weakened immune systems.  Symptoms typically include fever, muscle aches and sometimes gastrointestinal symptoms such as nausea or diarrhea. In rare cases, when the infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur. Although infected pregnant women will typically experience only mild flu-like syptoms, infections during pregnancy can in rare cases lead to miscarriage or stillbirth. When an infection does occur during pregnancy, antibiotics can often prevent infection of the fetus or newborn.

Listeria monocytogenes is typically found in soil and water. Vegetables can become contaminated from the soil or from fertilizer. Animals can carry the bacterium without appearing ill, which can lead also to the contamination of meats and dairy products. The pathogen has also been associated processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter. Unpasteurized (raw) milk, or foods made from unpasteurized milk, can also become contaminated with ListeriaAlthough the pathogen is killed by pasteurization and cooking, certain ready-to-eat foods such as hot dogs and deli meats can become contaminated prior to packaging.

Preventative Measures include:

  • Thoroughly cook raw food from animal sources, such as beef, pork, or poultry;
  • Wash raw vegetables thoroughly before eating;
  • Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods;
  • Avoid unpasteurized (raw) milk or foods made from unpasteurized milk;
  • Wash hands, knives, and cutting boards after handling uncooked foods; and
  • Consume perishable and ready-to-eat foods as soon as possible.

Additional recommendations for high risk individuals, such as pregnant women and persons with weakened immune systems, include:

  • Avoid hot dogs, luncheon meats and deli meats, unless they are fully cooked;
  • Avoid getting fluid from hot dog packages on other foods, utensils, and food preparation surfaces, and wash hands after handling hot dogs, luncheon meats, and deli meats;
  • Avoid soft cheeses such as feta, Brie, and Camembert, blue-veined cheeses, or Mexican-style cheeses such as queso blanco, queso fresco, and Panela, unless they have labels that clearly state they are made from pastuerized milk;
  • Avoid refrigerated pâtés or meat spreads. Canned or shelf-stable pâtés and meat spreads may be eaten; and
  • Avoid smoked seafood, unless it is contained in a cooked dish, such as a casserole. Refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna or mackerel, is most often labeled as "nova-style," "lox," "kippered," "smoked," or "jerky." The fish is found in the refrigerator section or sold at deli counters of grocery stores and delicatessens. Canned or shelf-stable smoked seafood may be eaten.


Listeria Images

Norovirus Fact Sheet

Noroviruses are members of a group of viruses called caliciviruses - also refered to as “Norwalk-like viruses.” Infection affects the stomach and intestines, causing an illness called gastroenteritis, or “stomach flu.”  The resulting inflammation of the stomach and intestines is not related to the flu (or influenza), which is a respiratory illness caused by influenza virus.

The symptoms of gastroenteritis include nausea, vomiting, and/or diarrhea accompanied by abdominal cramps. Some people also complain of headaches, fever, chills, and muscle aches.  Symtoms typically begin 24 to 48 hours after ingestion of the virus, but can appear as early as 12 hours after exposure. In turn, the resulting illness usually lasts for only 1 or 2 days. Although there is no evidence that infected individuals can become long-term carriers of the virus, it can remain in the stool and vomit of infected individuals for as long as 2 weeks after symptoms resolve.

Food and drinks can become contaminated with norovirus through contact with an infected person.  Food can be contaminated either by direct contact with contaminated hands or work surfaces that are contaminated with stool or vomit, or by tiny droplets from nearby vomit that can travel through air to land on food. Because the virus is so small, it takes relatively few norovirus particles to cause illness. Although the virus cannot multiply outside of human bodies, once on food or in water, it can cause illness.  Individuals can become infected with norovirus in several ways, including:

  • Eating food or drinking liquids that have been contaminated with norovirus;
  • Touching surfaces or objects contaminated with the virus, and then placing their hand in their mouth; and
  • Direct contact with another person who is infected and showing symptoms (for example, when caring for someone with illness, or when sharing foods or eating utensils).

Some foods can be contaminated with norovirus before being delivered to a restaurant or store. Several outbreaks have been caused by the consumption of oysters harvested from contaminated waters. Additionally, produce such as salads and frozen fruit may also become contaminated during harvesting and production.

People working with food who are sick with norovirus gastroenteritis are a particular risk to others, because they handle the food and drink many other people will consume.  A sick food handler can easily – without meaning to – contaminate the food he or she is handling. Many of those eating the contaminated food may become ill, causing an outbreak.

Most people recover completely within 1 to 2 days, with no long-term complications. In rare cases, however, persons who are unable to drink enough liquids to replace those lost from vomiting and/or diarrhea may become dehydrated and require special medical attention. These people include young children, the elderly, and persons unable to care for themselves.

As with most other pathogens, illness from norovirus can be easily avoided if proper hygienic and food handling procedures are followed.  Preventative Measures include:

  • Practice good hygiene, including thorough hand washing;
  • Disinfect potentially contaminated areas with a solution of detergent and chlorine bleach (sodium hypochlorite);
  • Routinely disinfect surfaces and furniture in common areas, such as lobbies and dining rooms. Where possible, allow bleach to stay on surfaces longer than 10 minutes;
  • Clean vomit with a two-step process: Collect visible debris with absorbent material, and then disinfect any surfaces that may have come in contact with vomit;
  • Avoid consuming raw shellfish, which may have been harvested from infected waters; and
  • Avoid contact sports if you have acute gastroenteritis;


Norovirus Images





Salmonella Fact Sheet

Salmonella is a Gram-negative, rod-shaped, motile bacteriumSalmonella serotype Typhimurium and Salmonella serotype Enteritidis are the most common in the United States, and have been known to cause illness for over 100 years. They were discovered by an American scientist named Salmon, for whom they are named. 

Although Salmonella is typically associated with raw and undercooked poultry products, the pathogen has also been found in a wide variety of other foods, including raw beef, milk and dairy products, fish and shrimp, frog legs, yeast, salad dressings, cake mixes, cream-filled desserts and toppings, dried gelatin, peanut butter, cocoa, chocolate and various pet foods. S. enteritidis creates additional challenges with respect to shell eggs, because, when present, the organism can survive inside the egg. 

In addition to direct contamination from source food products (such as eggs), Salmonella can also be transmitted from the contaminated feces of carriers (such as infected individuals) to foods, food product surfaces and other people.  Acute symptoms include nausea, vomiting, abdominal cramps, diarrhea, fever, and headaches. In extremely rare cases, chronic symptoms such as arthritis may develop 3-4 weeks following the onset of acute symptoms. Typically, the incubation period ranges between 12 and 36 hours. Although the infective dose usually requires only a relatively small number of bacteria, the amount ultimately depends upon the age and health of host.  In most cases, acute symptoms will only last for 1 to 2 days, and often do not require treatment other than oral fluids. Persons with severe diarrhea may require rehydration with intravenous fluids. Antibiotics, such as ampicillin, trimethoprim-sulfamethoxazole, or ciprofloxacin, are not usually necessary unless the infection spreads from the intestines.

As is the case with many other pathogens, illness from Salmonella can be easily avoided.  Preventative measures include:

  • Cooking poultry, ground beef, and eggs thoroughly to 160 degress F.  If you are served undercooked meat, poultry or eggs in a restaurant, do not hesitate to send it back to the kitchen for further cooking;
  • Avoiding foods containing raw eggs, or raw (unpasteurized) milk;
  • Washing hands, kitchen work surfaces, and utensils immediately after they have been in contact with raw meat or poultry products;
  • Being particularly careful when handling foods prepared for infants, the elderly, and those with weak immune systems;
  • Washing hands with soap after handling reptiles, birds, or baby chicks, and after potential contact with pet feces; and
  • Avoiding direct or even indirect contact between reptiles (turtles, iguanas, other lizards, snakes) and infants or immunocompromised persons;


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Shigella Fact Sheet

Shigella are Gram-positive, nonmotile, nonsporeforming rod-shaped bacteria. Shigella bateria were discovered over 100 years ago by a Japanese scientist named Shiga, for whom they are named. Currently, Shigella (shigellosis) accounts for approximately 10% of reported food-borne illness in the United States. There are several different kinds of Shigella that cause illness: Shigella sonnei, known as "Group D" Shigella, accounts for over two-thirds of shigellosis in the United States. In turn, Shigella flexneri, or "group B" Shigella, accounts for the majority of 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.

In addition to person to person transmission (through the fecal-oral route), Shigella may also be acquired from eating contaminated food, or by drinking or swimming in contaminated water. Incriminting foods have included salads (potato, tuna, shrimp, macaroni, and chicken), raw vegetables, milk and dairy products, and poultry. 

Shigella are highly infectious, and a relatively small number of organisms can cause illness.  In turn, illness is caused when Shigella organisms are consumed and then attach to and penetrate the epithelial cells of the intestinal mucosa.  After invasion, the bacteria multiply and spread to contiguous cells resulting in tissue destruction. Some strains produce enterotoxin and Shiga toxin (similar to the verotoxin of E. Coli O157:H7).  Symptoms include abdominal pain, cramps, diarrhea, fever, vomiting and/or blood or mucus in stools. Symptoms typically occur between 36 and 48 hours after the consumption of contaminated food, and will typically resolve within 4 to 7 days.  

As with other common food-borne pathogens, the spread of Shigella can be prevented by frequent and careful handwashing with soap.  


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Staphylococcus Fact Sheet

Staphylococcus aureus is a spherical bacterium (coccus) which typically appears in pairs, short chains, or bunched, grape-like clusters. These organisms are Gram-positive. The bacteria is capable of producing a heat-stable protein toxin that can cause illness.

Staphylococci can exist in air, dust, sewage, water, and food or on food equipment, environmental surfaces, humans, and animals. Humans and animals are the primary reservoirs. Staphylococci are present in the nasal passages and throats and on the hair and skin of 50 percent or more of healthy individuals. This incidence is even higher for those who associate with, or who come in contact with, sick individuals and hospital environments.  Although food handlers are usually the main source of food contamination in food poisoning outbreaks, equipment and environmental surfaces can also be sources of contamination with staphylococcus.

Notably, foods that require considerable preparation (using hands), and are maintained at slightly elevated temperatures, are frequently associated with outbreaks.  These foods typically include salads products (such as egg, tuna, chicken, potato, and macaroni) and bakery products (such as cream-filled pastries and cream pies).  Other foods associated with outbreaks have included sandwich fillings, dairy products, meat products, poultry and egg products.

If Staphylococci are introduced into food, the bacteria can multiply and develop pre-formed enterotoxins.  This usually occurs if the food is not kept hot enough (140°F or above) or cold enough (45°F or below).  Once ingested, illness can be caused by the preformed enterotoxins.  A toxin dose of less than 1.0 microgram in contaminated food, which is reached when the bacterial population exceeds 100,000 per gram, can produce symptoms.

The onset of symptoms in staphylococcal food poisoning is usually rapid and in many cases acute, depending on individual susceptibility to the toxin, the amount of contaminated food eaten, the amount of toxin in the food ingested, and the general health of the individual. The most common symptoms include nausea, vomiting, abdominal cramping and prostration. Some individuals may not always demonstrate all the symptoms associated with the illness. In more severe cases, headache, muscle cramping, and transient changes in blood pressure and pulse rate may occur.  Recovery generally takes only two days.

As is true with most other common food-borne pathogens, the spread of Staphylococci to foods can be prevented by following good hygienic practices.


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