Food-borne illnesses are diverse in etiology, and food poisoning can follow ingestion of infectious organisms or noninfectious substances. Food-borne diseases (FBDs) constitute a serious public health problem in the United States. FBDs encompass classic toxin-mediated food poisoning, such as botulism; gastroenteritis that follows ingestion of preformed Staphylococcus aureus toxin; ingestion of chemicals in foods; and bacterial (see the image below), parasitic, and viral infections. Many FBDs are zoonoses, which implies that the infectious agent has a primary animal reservoir and that humans are affected incidentally.
View Image
Escherichia coli on Gram stain. Gram-negative bacilli.
See 5 Cases of Food Poisoning: Can You Identify the Pathogen?, a Critical Images slideshow, to help identify various pathogens and symptoms related to foodborne disease.
Although the GI tract is the primary target, autonomic nervous system disturbances and CNS impairment are prominent manifestations in chemical-related, plant-related, and seafood-related poisonings and in botulism. The severity of dehydration can vary depending on the pathogen.
Typically, FBDs in which severe vomiting (eg, staphylococcal-toxin gastroenteritis) and small bowel diarrhea occur, typified by Vibrio cholerae infection, can cause life-threatening dehydration. Other organs involved include the liver in hepatitis A, muscles in trichinosis, lymph nodes in toxoplasmosis, and, importantly, the kidneys in hemolytic-uremic syndrome (HUS), which follows enterohemorrhagic Escherichia coli -induced diarrhea.
See the image below.
View Image
Escherichia coli on Gram stain. Gram-negative bacilli.
The US Centers for Disease Control and Prevention (CDC) estimates 1 in 6 Americans (48 million people) are affected by foodborne illness annually. The estimates suggest 128,000 people are hospitalized and 3,000 die.[1] The 31 known pathogens account for an estimated 9.4 million annual cases, 55,961 hospitalizations, and 1,351 deaths. Unspecified agents account for 38.4 million cases, 71,878 hospitalizations, and 1,686 deaths.[2]
The most common pathogens are as follows:[1]
Norovirus – 5,461,731 cases
Salmonella – 1,027,561
Clostridium perfringens – 965,958
Campylobacter species – 845,024
Staphylococcus aureus – 241,148
The most common pathogens responsible for hospitalizations are as follows:[1]
Salmonella – 19,336 hospitalizations
Norovirus – 14,663 hospitalizations
Campylobacter species – 8,463 hospitalizations
Toxoplasma gondii – 4,428 hospitalizations
E coli – 2,138 hospitalizations
The pathogens most commonly associated with death are as follows:
Salmonella – 378 deaths
T gondii – 327 deaths
Listeria monocytogenes – 255 deaths
Norovirus – 149 deaths
Campylobacter species – 76 deaths
The CDC recognized the following outbreaks and sources in 2012:[1]
E coli – Spinach and spring mix, raw clover sprouts at Jimmy John’s restaurants
Salmonella – Peanut butter, FrescolinaMarte brand ricotta salata cheese, mangoes, cantaloupe, ground beef, live poultry, dry dog food, raw scraped ground tuna product, small turtles, raw clover sprouts
International
International statistics are probably impossible to compute, but the obvious relevance of worldwide FBDs is the risk to travelers in the very mobile American and world population and the estimated 2 million deaths in children alone.[3, 4, 5]
Mortality/Morbidity
The epidemiologic relevance of FBD is that outbreaks can involve an immense number of individuals and have the potential to overwhelm local health care services. Death can occur in a small proportion of affected patients; therefore, practitioners must take responsibility for reporting suspected FBDs and participate in investigations by the agency (eg, by saving food or vomitus samples).
Race
No specific racial predilection is noted, except that invasive Salmonella infections are more prevalent in individuals with hemoglobinopathies, which, in turn, are more common among people of African and Mediterranean descent.
Sex
No sex predilection is known for any food-borne illness; however, Listeria infection is often severe and life threatening in pregnant women.
Age
The CDC found that 5 bacterial enteric pathogens (Campylobacter, E coli 0157 , Salmonella, Shigella, and Y enterocolitica) caused 291,162 illnesses annually in children younger than 5 years.[6] This resulted in 102,746 doctor visits, 7,830 hospitalizations, and 64 deaths. Rates of illness remain higher in children.
Because few food-borne illnesses present with their own pathognomonic clinical picture, and because laboratory tests are of limited value in acute food poisoning, a systematic interrogation of patients and their families is the best way to deduce the etiology. Immediately following initiation of supportive treatment, the practitioner should obtain a history in the areas described below. This allows the list of possible agents to be narrowed, which helps dictate treatment and laboratory investigation.
A statement of the etiology and a brief description of the illness are included with each of the 4 incubation periods (ie, intervals between suspected food and onset of illness) to help relate this important historical clue to the specific infective agent.
Short incubation (ie, within 1 d, usually < 16 h)
See the list below:
Chemical causes (ultrashort incubation): The onset of nausea, vomiting, and cramps within 1-2 hours is observed in poisonings involving metal, fish-associated toxins (eg, scombroid, ciguatera), shellfish-associated toxins, monosodium glutamate, or mushrooms. The toxic agent in shellfish-related and ciguatera-related disease is derived from dinoflagellate organisms present in the fish or shellfish. Note that neurologic symptoms can present weeks later. Amanita mushrooms can lead to hepatorenal failure.
Bacterial causes - Emetic syndrome (1-6 h)
S aureus: Nausea and vomiting are caused by the action of preformed enterotoxins A-E.
Bacillus cereus (emetic syndrome, indistinguishable from staphylococcal food poisoning): This spore-forming rod is present in raw rice grains. The emetic toxin is a preformed heat-stable toxin produced upon germination of the spores.[7] Bacterial causes - Diarrheal syndrome (8-16 h)
B cereus (diarrheal syndrome): The diarrheal toxin is a heat-labile toxin formed after sporulation.
C perfringens type A: Diarrhea and abdominal cramps occur within 1 day of ingestion of cooked meat stored at 15-60°C. Slow cooling allows heat-activated spores to germinate and to elaborate the enterotoxin.
Intermediate incubation (1-3 d)
See the list below:
Diarrheal disease: This category comprises bacterial and viral infectious pathogens. The clinical presentation depends on the target organ (ie, small bowel or large bowel), which varies depending on the pathogen.
Diarrheal disease, large bowel enteritis: Fever and constitutional symptoms usually accompany the diarrhea caused by invasive pathogens in the large bowel. Dysentery, bloody stools with mucous, and cramps or tenesmus are typical. Campylobacter jejuni: This is a leading cause of bacterial food-borne illness in the United States. Vomiting is uncommon, and the illness is short and self-limiting.
Shigella species: Shigellae cause the prototypical diarrheal syndrome with blood, mucous, and pain that is termed bacillary dysentery. Tenesmus and small-volume stools are typical. Toxemia may be severe, occasionally causing seizures in children.
Enteroinvasive E coli (EIEC): Several serotypes of diarrheagenic E coli possess Shigella -like invasiveness factors that allow mucosal invasion. The disease is a febrile dysentery that mimics shigellosis.
Salmonella species, nontyphoidal salmonellosis: This is a zoonotic infection acquired from bovine or poultry reservoirs and is very common in the United States. The illness can range from mild nonbloody diarrhea to a severe dysenteric illness.
Salmonella species, enteric (typhoid) fever: In the United States, enteric fever occurs in travelers or recent immigrants and is a systemic toxic illness. Salmonella typhi has an exclusively human reservoir and is acquired either via ingestion of a large inoculum in food or contaminated water or from personal contact with a carrier.
Vibrio parahaemolyticus: Although it is a common worldwide pathogen, in the United States, V parahaemolyticus infection is restricted geographically to the Atlantic and Gulf coasts. The diarrhea is profuse and watery, and blood is not commonly present in the stool.Diarrheal disease, small bowel enteritis
Enterotoxigenic E coli (ETEC): Enterotoxin-producing strains of E coli are the most common cause of traveler's diarrhea. The diagnosis is clinical; fever and bloody stools are typically absent.
Vibrio cholerae (01 and non-01 strains): Cholera is likely only in endemic areas and during epidemics. The profuse diarrhea and vomiting can lead to dehydration and prostration.
Viral agents (Norwalklike viruses, rotavirus, adenoviruses, astroviruses, caliciviruses): Vomiting and headache accompany the diarrhea and fever more commonly with viral than with bacterial infections.
All the large bowel pathogens also secrete enterotoxins that induce profuse watery small bowel diarrhea in some patients.
Botulism: Nausea, vomiting, skeletal muscle paralysis, and autonomic symptoms occur within 18-36 hours of ingestion of food containing Clostridium botulinum. The disease is mediated by preformed toxin in older children and adults, but it may follow ingestion of spores in infants. Diarrhea occurs only in approximately 5% of patients; instead, constipation may be noted. Infants with botulism present with muscular weakness that manifests as weak cry, difficulty sucking and swallowing, or respiratory failure. Upon examination, the baby has profound hypotonia but may be alert.
Long incubation (3-5 d)
See the list below:
Enterohemorrhagic E coli (EHEC): These strains of E coli cause hemorrhagic colitis with a 15% risk of progression to hemolytic-uremic syndrome (HUS) in children, which is the result of cytotoxins termed verotoxins or Shigalike toxins. E coli O157:H7 is one of many such cytotoxin-producing E coli strains that reside in the gut of cattle. Although these organisms can cause mild nonbloody diarrhea, hemorrhagic colitis is the usual symptom. Mild abdominal pain, malaise, and transient fever are followed by watery diarrhea. Bloody stools and more severe abdominal pain ensue several days later. Paucity of fever is a diagnostic clue. When HUS occurs, its onset is 5-13 days after the onset of diarrhea.
Yersinia species
Yersinia enterocolitica most often causes a febrile illness with abdominal pain due to mesenteric lymphadenitis in which diarrhea is not prominent. The illness can mimic appendicitis. The illness may be prolonged, lasting 2-3 weeks. In infants, a diarrheal illness is common, with occasional septicemia. The diagnosis is made with blood and stool cultures. Treatment is indicated only for infants with septicemia.[8]
The symptom complex for Yersinia pseudotuberculosis infection includes fever, rash (scarlatiniform or erythema nodosum), and abdominal pain.
Very long incubation (1-4 wk): This category comprises parasitic food-borne diseases (FBDs), but shorter incubation periods can occur, especially in Entamoeba histolytica infection.
Parasitic
Giardiasis: The spectrum of illness ranges from asymptomatic carriage to acute watery diarrhea, but a subacute intermittent diarrheal illness is also common.
Amebiasis: E histolytica is a protozoan that causes dysentery and extraintestinal, most commonly hepatic, abscesses.
Cryptosporidiosis: The organism Cryptosporidium parvum causes a diarrheal illness with fever and abdominal pain.
Cyclosporiasis: Frequent watery stools, which can be accompanied by fever and a relapsing course, characterize this FBD caused by Cyclospora cayetanensis.
Trichinosis: This is a rare illness, caused by Trichinella spiralis, that is acquired by ingestion of contaminated or raw pork, bear, or moose meat. GI tract symptoms are followed by muscle inflammation and periorbital edema.
Cysticercosis: This infection is caused by the larval stage of pork tapeworm and is most often acquired by ingestion of food or water contaminated with the ova of the tapeworm rather than from eating raw pork.
Anisakiasis, fish tapeworm, and flatworm infections: These uncommon worm infestations occur after consumption of certain types of raw fish.
Bacterial
Listeriosis: Diarrhea in Listeria monocytogenes infection may be mild, but systemic symptoms are prominent. The diarrhea has a short incubation period (< 48 h), but symptoms of systemic spread could appear weeks later. The major risk is that of maternal infection during pregnancy. Neonatal sepsis and meningitis follow amniotic fluid infection. Older children and adults can develop meningitis. The infection is a particular hazard to individuals who are immunocompromised.
Brucellosis: This is a febrile illness now only rarely acquired in the United States. The food source is raw or unpasteurized milk or cheese, most commonly from goats (Brucella melitensis).
Viral: The incubation period of hepatitis A is 15-50 days for this viral hepatitis transmitted via the fecal-oral route.
Protozoal, toxoplasmosis: A febrile and subacute lymphadenitis results from ingestion of undercooked meat. A nonspecific illness with systemic symptoms and generalized lymphadenopathy can occur in healthy individuals, or an asymptomatic infection can result. Persons who are immunocompromised can develop CNS infection.
Type of food consumed: The following is a checklist of commonly implicated food items that may suggest the etiology of a FBD:
Food sources
See the list below:
Tap water when traveling abroad
Undercooked eggs, egg salad, or egg-containing salad dressings
Shellfish, including mussels, oysters, or scallops
Wild mushrooms
Fish
Ciguatera - Grouper, red snapper, barracuda, or amberjack
Scombroid - Tuna, bluefin tuna, skipjack, mackerel, marlin, mahimahi, or puffer fish
Raw fish prepared at home (sashimi or sushi, especially Alaskan salmon, rockfish)
Meat (specify if undercooked or wild game)
Unpasteurized milk, cheese, eggnog, ice cream, or juices[9]
Cream pastries or cookie and cake batters
Home-canned goods
Food in corroded metal containers
Fresh produce, including fruit[10]
Hot dogs, deli meats, or chitterlings (ie, pork innards)
Stool culture is an expensive test with a very low yield and is indicated particularly if patients with food poisoning have bloody diarrhea, severe abdominal pain, or are immunocompromised. When the likely pathogen is a Campylobacter, Yersinia, or Vibrio species, or if Shigalike toxin-producing E coli (eg, E coli O157:H7) is suspected, the laboratory should be notified because special media or incubation conditions (high or low temperature) are required.
Stool examination for parasites is indicated for GI tract illnesses that appear to have occurred after a long incubation period. Certain travel history, such as travel to tropical countries, camping, and drinking well or stream water should prompt consideration of parasitic food-borne illness.
Blood cultures are performed for bacteremic food-borne diseases (FBDs).
Serum electrolyte levels, BUN levels, creatinine levels, CBC count, and urinalysis are performed to assess hydration, renal function, and presence of hemolytic-uremic syndrome (HUS). Evidence of hemolysis and thrombocytopenia are present in patients with HUS.
Toxin testing, serotyping, and molecular techniques are available only from large commercial and public health laboratories. They are generally ordered only as part of an epidemiologic investigation.
Testing of food or vomitus for toxins may be offered by a poison control center or the local health authorities.
The mainstay of medical treatment in food poisoning is fluid and electrolyte replenishment. Guidelines for the diagnosis and management of food-borne illnesses have been established by the American Medical Association, American Nurses Association-American Nurses Foundation, the Centers for Disease Control and Prevention, Center for Food Safety and Applied Nutrition, the US Food and Drug Administration (FDA), Food Safety and Inspection Service, and US Department of Agriculture.[11]
The treating physician should be careful not to assign blame for the cause of food poisoning, for example, a particular restaurant or gathering, since the information available is almost always circumstantial until health or law enforcement officials have completed an investigation.
Bioterrorism or negligence of hygiene may be suspected but difficult to prove by the physician.
Immediate specific antibiotic therapy is not indicated in most food-borne illnesses; therefore, the physician should not be concerned about medicolegal pitfalls regarding failure to prescribe an antibiotic. In fact, in enterohemorrhagic E coli (EHEC) infection that may lead to hemolytic-uremic syndrome (HUS), antibiotics are contraindicated.[12]
Most food-borne diseases (FBDs) are not amenable to specific antidotes or antimicrobial therapy, but the few exceptions are mentioned below.
Short incubation
See the list below:
Chemical/mushroom: Treatment varies depending on the chemical or toxin. Consult with staff at a poison control center or an emergency manual. For most agents, the care is supportive only. Exceptions include intravenous mannitol for ciguatera toxin, antihistamines for scombroid poisoning, and atropine or physostigmine for poisoning with certain mushrooms.
Bacterial: No specific therapy is indicated. Institute rehydration.
Intermediate incubation
See the list below:
Campylobacter infections: A macrolide, especially erythromycin, and possibly azithromycin, a quinolone, or a parenteral aminoglycoside (eg, gentamicin) are indicated. However, symptoms often resolve by the time culture results are received.
Shigella infection: Antibiotic treatment of infection is currently problematic because of increasing rates of resistance.[13] Treatment is important to prevent transmission. Azithromycin, third-generation cephalosporins (including oral cefixime or cefpodoxime), and ciprofloxacin are choices based on laboratory susceptibility testing. Consultation with a pediatric infectious diseases specialist is highly recommended.
Salmonella infection: Institute rehydration. Administer parenteral extended-spectrum cephalosporin if bacteremia occurs.
Salmonella enteric fever: A typical regimen is a parenteral cephalosporin followed by oral amoxicillin, quinolone or cefixime based on susceptibility. A study that described changes in antimicrobial resistance among nontyphoidal Salmonella in the United States from 1996 through 2009 reported an increase in resistance to ceftriaxone and nonsusceptibility to ciprofloxacin and an overall decline in multidrug resistance.[14, 15]
V cholerae, V parahaemolyticus, Vibrio vulnificus: Institute rehydration; a tetracycline can be administered to children older than 8 years.
Enterotoxigenic E coli (ETEC): For rapid resolution of illness, a short course of a quinolone, trimethoprim-sulfamethoxazole (TMP-SMZ), azithromycin, or rifaximin can be administered on an outpatient basis.
Norwalklike virus, rotavirus, or other viruses acquired via the fecal-oral route: Supportive care is indicated. Rehydration is especially important for infants with rotavirus infection.
Botulism: Treatment is chiefly supportive, with the notable exception of infant botulism, for which an antitoxin (BabyBIG) is available from the California Department of Health Services. Contact them at (510) 231-7600 to review the indications for such treatment. Rarely, use of a botulinum antitoxin can be considered in older children by contacting the CDC at 800-CDC-INFO.[16, 17]
Long incubation
See the list below:
Enterohemorrhagic E coli (EHEC): Most studies suggest that antibiotics are likely to increase the risk of developing hemolytic-uremic syndrome (HUS). Treatment, including treatment of HUS, is supportive.
Yersinia enterocolitica infection: Treatment is supportive. Parenteral aminoglycosides or third-generation cephalosporins are indicated if bacteremia is present.
Very long incubation
See the list below:
Giardiasis: Metronidazole is the drug of choice, but tinidazole and nitazoxanide may be better tolerated.
Amebiasis: Metronidazole followed by an luminal agent, usually tinidazole or paromomycin, is indicated.
Cryptosporidiosis: The illness is brief and self-limiting. Nitazoxanide or paromomycin are considered in severe cases.
Cyclosporiasis: TMP-SMZ may be an effective treatment for the immunocompromised host.
Listeria Infection: Intravenous ampicillin or TMP-SMZ is administered to treat systemic Listeria infection.
Brucellosis: A combination of doxycycline and streptomycin is the regimen of first choice.
Consultation with an infectious disease specialist may be beneficial in complicated or unusual cases.
For chemical or mushroom poisonings, consult with a poison control center for advice on specific antidotes and for help with identifying the implicated mushrooms.
For suspected point-source outbreaks of staphylococcal toxins or infective pathogens, call the local health department. Staff members usually have information regarding the species or strain involved and its antibiotic susceptibility.
As with other pediatric gastroenteritides, dietary restrictions are no longer are the standard of care, and the child is allowed solid foods as desired to maintain nutritional status.
Prevention of food-borne diseases (FBDs) occurs on 2 levels.
Level 1: The CDC has initiated a major educational initiative for practitioners and the lay public to recognize, report, and prevent FBDs. Part of this effort is "Fight BAC!".
Level 2: The second level of prevention is at the individual level.
Care with food preparation, good hand-washing technique, and refrigeration are essential to prevention of FBDs. Particular care should be taken with foods offered to persons who are pregnant or who are immunocompromised. A good axiom is never to serve reheated leftovers to these individuals.
Unfortunately, many diseases are difficult to prevent, and following a vegetarian diet does not guarantee that organisms customarily associated with meat (eg, Shiga toxin-producing E coli, Listeria species, cysticerci) will not be a hazard. The seafood that causes chemical food poisoning is not obviously spoiled; therefore, the occurrence is unpredictable. Most mushroom toxins are not destroyed by heating.
For excellent patient education resources, visit eMedicineHealth's Digestive Disorders Center and First Aid and Injuries Center. Also, see eMedicineHealth's patient education articles Food Poisoning, Gastroenteritis, Vomiting and Nausea, and Diarrhea.
Sunil K Sood, MBBS, , MD, Professor of Clinical Pediatrics, Department of Pediatrics, Albert Einstein College of Medicine; Chief, Pediatric Infectious Diseases, Firm Director, Pediatric Unit, Schneider Children's Hospital at North Shore, North Shore University Hospital
Disclosure: Nothing to disclose.
Specialty Editors
Mary L Windle, PharmD, Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Nothing to disclose.
Larry I Lutwick, MD, FACP, Editor-in-Chief, ID Cases; Moderator, Program for Monitoring Emerging Diseases; Adjunct Professor of Medicine, State University of New York Downstate College of Medicine
Disclosure: Nothing to disclose.
Chief Editor
Russell W Steele, MD, Clinical Professor, Tulane University School of Medicine; Staff Physician, Ochsner Clinic Foundation
Disclosure: Nothing to disclose.
Acknowledgements
Rosemary Johann-Liang, MD Medical Officer, Infectious Diseases and Pediatrics, Division of Special Pathogens and Immunological Drug Products, Center for Drug Evaluation and Research, Food and Drug Administration
Rosemary Johann-Liang, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, and Infectious Diseases Society of America
){kind=link}