|
| A) | It is a sentinel surveillance program comprised of 11 geographic areas. | ||
| B) | It monitors incidence of infections caused by nine foodborne enteric pathogens. | ||
| C) | It detects trends in preventable foodborne infection and seeks to promote food safety. | ||
| D) | All the above |
The Foodborne Diseases Active Surveillance Network (FoodNet) was established in 1996 to monitor the incidence and trends of foodborne disease in the United States. FoodNet is a collaborative effort between the Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (FDA), the U.S. Department of Agriculture (USDA), and state health departments. Designed as a sentinel program, FoodNet expanded its catchment area in 2023 (adding Colorado) and now conducts active, population-based surveillance across 11 geographic areas covering 16% of the population (53.6 million persons) [2]. FoodNet public health officials routinely communicate with more than 700 clinical laboratories to assure that identification of new infections is timely, accurate, and thorough. The system monitors incidence of laboratory-confirmed infections caused by nine enteric bacterial and parasitic pathogens commonly acquired by exposure to contaminated food. A preliminary summary report of data from the previous year is published in the Morbidity and Mortality Weekly Report each spring. In 2023, FoodNet identified 26,607 cases, 7,234 hospitalizations, and 177 deaths attributable to foodborne diseases [2]. The overall incidence per 100,000 population was highest for Campylobacter (23.4), followed by Salmonella (16.6), Shiga toxin-producing Escherichia coli (STEC) (4.7), and Shigella (4.8). Incidences of Campylobacter and STEC infection increased in 2023, whereas the incidence of Salmonella and Shigella remained stable.
| A) | 4 million illnesses. | ||
| B) | 14 million illnesses. | ||
| C) | 48 million illnesses. | ||
| D) | 148 million illnesses. |
According to the World Health Organization, a foodborne disease is "usually infectious or toxic in nature, caused by bacteria, viruses, parasites, or chemical substances entering the body through contaminated food or water" [29]. More than 250 specific pathogens or toxins have been identified as causes of human foodborne disease worldwide. An estimated 600 million people—almost 1 in 10 people in the world—fall ill after eating contaminated food and 420,000 die every year [29]. Children younger than 5 years of age account for 40% of the foodborne disease burden, with 125,000 deaths every year. In 2018, the World Bank estimated that the total productivity loss associated with foodborne disease in low-and-middle income countries cost $95.2 billion per year, and the annual cost of treating foodborne illnesses cost $15 billion [238]. In the United States, after combining the estimates for known pathogens and unspecified agents, the annual burden of foodborne diseases is estimated to be 48 million illnesses, 128,000 hospitalizations and 3,000 deaths [30]. The estimated annual economic burden is $77.7 billion, mainly due to healthcare costs and lost productivity [31]. Despite increased surveillance, intensified awareness/education campaigns, and improved food safety, the incidence of foodborne disease has not changed significantly since the late 1990s, and it may increase further as a result of the expanding global food economy and the increased threat of bioterrorism [32].
| A) | All food-related illnesses are caused by parasites. | ||
| B) | Viruses replicate in human intestines, not in foods. | ||
| C) | Foodborne infections cannot be spread through droplet transmission. | ||
| D) | Approximately 90% of all cases of acute gastroenteritis are attributable to foodborne disease. |
The hallmark characteristics of an infectious food-related illness are gastrointestinal symptoms, most notably diarrhea, abdominal cramps, and vomiting. However, some individuals may be asymptomatic or only mildly ill. Approximately 36% of all cases of acute gastroenteritis are attributable to foodborne disease [36].
| A) | Vibrio | ||
| B) | Shigella | ||
| C) | Listeria | ||
| D) | Salmonella |
LABORATORY-DIAGNOSED BACTERIAL AND PARASITIC FOODBORNE INFECTIONS IN 2023a
| Pathogen | No. of Cases | Incidence per 100,000 | ||
|---|---|---|---|---|
| Campylobacter | 11,926 | 23.4 | ||
| Salmonella | 8,454 | 16.6 | ||
| Shigella | 3,186 | 6.2 | ||
| STEC O157 | 3,351 | 6.6 | ||
| Cyclospora | None identified | — | ||
| Yersinia | 1,437 | 2.8 | ||
| Vibrio | 567 | 1.1 | ||
| Listeria | 163 | 0.3 | ||
| ||||
| A) | younger than 5 years of age. | ||
| B) | 5 to 9 years of age. | ||
| C) | 20 to 59 years of age. | ||
| D) | 60 years of age and older. |
FoodNet surveillance data show that the highest incidence of bacterial foodborne disease is found among children younger than 5 years of age, followed by children 5 to 9 years of age (Table 4) [76]. The most common causative pathogens in these two age groups are Salmonella, Campylobacter, and Shigella [76,77]. Only Vibrio and Listeria infections occur more frequently in older individuals than in children. Among individuals 60 years of age or older, Salmonella and Campylobacter are the leading causes of bacterial foodborne infection [76].
| A) | Giardia | ||
| B) | Cyclospora | ||
| C) | Cryptosporidium | ||
| D) | Toxoplasma gondii |
INCIDENCE OF LABORATORY-CONFIRMED BACTERIAL AND PARASITIC FOODBORNE DISEASE ACCORDING TO AGE
| Pathogen | Incidence (per 100,000) | ||||
|---|---|---|---|---|---|
| <5 years of age | 5 to 9 years of age | 10 to 19 years of age | 20 to 64 years of age | >65 years of age | |
| Bacteria | |||||
| Salmonella | 63.5 | 19.3 | 11.3 | 12.2 | 17.2 |
| Campylobacter | 24.1 | 10.5 | 9.4 | 14.5 | 15.3 |
| Shigella | 16.9 | 14.8 | 2.9 | 3.1 | 1.4 |
| STEC O157 | 4.7 | 2.3 | 1.7 | 0.6 | 0.7 |
| STEC non-O157 | 4.8 | 1.3 | 1.7 | 0.7 | 0.9 |
| Yersinia | 1.3 | 0.3 | 0.2 | 0.2 | 0.5 |
| Listeria | 0.2 | — | 0.03 | 0.2 | 1.1 |
| Vibrio | 0.1 | 0.3 | 0.1 | 0.4 | 0.8 |
| Parasites | |||||
| Cryptosporidium | 3.7 | 3.1 | 1.7 | 2.5 | 3.0 |
| Cyclospora | — | — | — | 0.04 | 0.03 |
| A) | Vibrio | ||
| B) | Shigella | ||
| C) | Listeria | ||
| D) | Salmonella |
Most foodborne infections result in self-limited illness that resolves within a few days to a week. Severity of illness caused by bacterial foodborne disease varies by etiology, as evidenced by hospitalization rates reported by FoodNet for 2016 (Table 5) [92]. The case-fatality rate also varies by pathogen; mortality rates in 2015 were 12.9% for Listeria, 2.6% for Vibrio, 0.4% for Salmonella, and 0.2% for Campylobacter [93]. Hospitalization and mortality rates are somewhat higher among persons older than 65 years of age, and the hospitalization rate for children younger than 5 years of age ranges from 11.3% for Shigella to 100% for Listeria foodborne infections [93].
| A) | Shigella | ||
| B) | Bacillus cereus | ||
| C) | Campylobacter jejuni | ||
| D) | Staphylococcus aureus |
COMMON ASSOCIATIONS BETWEEN PATHOGENS AND SPECIFIC FOOD SOURCES
| Food Source | Pathogens | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Beef |
| ||||||||||
| Poultry |
| ||||||||||
| Pork |
| ||||||||||
| Meat products, gravies |
| ||||||||||
| Raw (unpasteurized) milk and dairy products (soft cheeses) |
| ||||||||||
| Raw and undercooked eggs | Salmonella | ||||||||||
| Improperly canned goods; smoked or salted fish | Clostridium botulinum | ||||||||||
| Fresh or minimally processed produce (vegetables, fruit) |
| ||||||||||
| Shellfish (raw or undercooked) |
| ||||||||||
| Processed meats |
| ||||||||||
| Rice products and other starchy foods, including potato, pasta, and cheese products | Bacillus cereus (emetic type) | ||||||||||
| Prepared salads (potato, tuna, macaroni, chicken) and sandwiches |
| ||||||||||
| Puddings, custards, pastries |
| ||||||||||
| Fruit juices (unpasteurized) |
|
| A) | Norovirus, mollusks | ||
| B) | Scombroid toxin, fish | ||
| C) | Salmonella, poultry/pork | ||
| D) | All of the above |
The source of a food-related illness cannot always be identified; approximately 56% of cases have no known cause [66,67]. In 2015, an identifiable food source accounted for approximately 46% of outbreaks of known etiology [44]. The number of outbreaks and infected individuals associated with a food source varies over time. In 2008, poultry was the most common source, associated with 32 outbreaks; in 2015, fish was the leading source, associated with 222 outbreaks [44,66,67]. The highest number of foodborne infections was associated with exposure to vegetables (1,596) in 2002, to poultry (1,355) in 2006, to fruits and nuts (1,755) in 2008, and to chicken (3,114) in 2009–2015 [66,67]. Analysis of data from 2016 demonstrated that the top six pathogen-food source pairs representing the most outbreaks/illnesses were [92]:
Scombroid or ciguatoxin in fish (23 outbreaks, 68 illnesses)
Salmonella in chicken (8 outbreaks, 307 illnesses)
Campylobacter in dairy (7 outbreaks, 57 illnesses)
Norovirus in mollusks (6 outbreaks, 209 illnesses)
Salmonella in pork (6 outbreaks, 96 illnesses)
Vibrio parahaemolyticus in mollusks (6 outbreaks, 19 illnesses)
| A) | tuna. | ||
| B) | lobster. | ||
| C) | mussels. | ||
| D) | grouper. |
SOURCES OF MARINE TOXINS
| Toxin | Fish |
|---|---|
| Ciguatoxin | Grouper, snapper, amberjack, mackerel, triggerfish, barracuda |
| Tetrodotoxin | Pufferfish |
| Scombroid | Tuna, mahi mahi, bluefish, sardines, mackerel, amberjack, abalone |
| Shellfish Toxins | |
| Paralytic | Mussels, clams, cockles, scallops |
| Diarrhetic | Mussels, oysters, scallops, clams |
| Neurotoxic | Shellfish harvested along the Florida coast and the Gulf of Mexico |
| Amnesic | Bivalve mollusks, crabs, lobsters |
| A) | a virus. | ||
| B) | a toxin. | ||
| C) | a parasite. | ||
| D) | bacteria. |
FOUR DIAGNOSTIC CLUES TO DETERMINE THE ETIOLOGY OF A FOODBORNE ILLNESS
| Diagnostic Clue | Likely Etiology |
|---|---|
| Incubation Period (Time to Onset of Symptoms) | |
| Very short (hours) | Toxin |
| Approximately one day | Virus |
| Several days | Bacteria |
| Duration of Illness | |
| Short | Virus or toxin |
| Long | Bacteria |
| Predominant Clinical Symptoms | |
| Diarrhea | Virus or bacteria |
| Vomiting | Toxin |
| Severe illness | Bacteria |
| Population Involved in the Outbreak | |
| Closed population (school, healthcare facility) | Virus |
| Large catered event | Toxin or virus |
| A) | Giardia | ||
| B) | Shigella | ||
| C) | Salmonella | ||
| D) | STEC O157 |
DIFFERENTIAL DIAGNOSIS OF FOODBORNE ILLNESSES ACCORDING TO SYMPTOMS ON CLINICAL PRESENTATION
| Symptom | Possible Diagnosis | |||||||
|---|---|---|---|---|---|---|---|---|
| Gastroenteritis, with vomiting as primary symptom (fever and/or diarrhea may also be present) |
| |||||||
| Noninflammatory diarrhea (acute watery diarrhea, usually without fever) |
| |||||||
| Inflammatory diarrhea (grossly bloody stool, fever, invasive gastroenteritis) |
| |||||||
| Persistent diarrhea (14 days or more) |
| |||||||
| Neurologic symptoms (paresthesias, respiratory depression, bronchospasm, cranial nerve palsies) |
| |||||||
| Systemic illness (fever, weakness, arthritis, jaundice) |
|
| A) | Shigella | ||
| B) | Salmonella | ||
| C) | STEC O157 | ||
| D) | Campylobacter jejuni |
Routine stool culture examinations vary according to the particular suspected pathogens, and practitioners should be aware of pathogens that must be specifically requested. Many physicians surveyed have said they do not know whether stool culture examination includes testing for some specific species (e.g., Yersinia, Vibrio, STEC O157) [112]. A routine stool culture usually includes screening for Salmonella and Shigella species and Campylobacterjejuni or coli[21]. As such, if Vibrio, Yersinia, STEC O157, or Campylobacter species other than jejuni/coli is suspected, the practitioner should communicate this to, and consult with, the receiving clinical microbiology laboratory.
| A) | The list of nationally notifiable diseases is updated each year. | ||
| B) | Practitioners should report nationally notifiable diseases directly to the CDC. | ||
| C) | Reporting of a nationally notifiable disease is best done by the clinical laboratory. | ||
| D) | A nationally notifiable disease should be reported only after laboratory confirmation. |
Because healthcare professionals are often the first to identify foodborne illnesses, they are the frontline protection for the public against many foodborne disease outbreaks [21]. Prompt and accurate disease reporting to the local or state health department is necessary for the prevention and control of outbreaks as well as for accurate surveillance [17,21]. Healthcare practitioners should be familiar with the list of nationally notifiable diseases and check with the CDC for the most recent list, as it is updated annually [114].
The CDC recommends that suspected foodborne-illness outbreaks or sporadic illnesses that may be caused by a nationally notifiable disease should be reported as soon as possible [21]. Because early intervention is crucial, definitive diagnoses are unnecessary [17,21]. Links to state health department websites, which include contact information for local health departments, are available on the CDC website. When reporting, the practitioner should provide the following information to the local or state health department [117,118]:
Date of illness(es)
Age, sex, and full residence address and phone number for patient(s)
Symptom complexes (especially unusual symptoms)
Disease patterns
Local or state health departments may communicate additional requests or requirements to practitioners under their jurisdiction.
Many practitioners leave the reporting responsibilities up to the clinical laboratory [117,118]. However, the practitioner should report the illness because he or she is the one who is uniquely able to describe symptomatic clusters and communicate other specific information [117]. Practitioner failure to report foodborne illnesses has led to missed opportunities for the implementation of early prevention measures and postexposure prophylaxis [117].
| A) | is highest in the summer and fall. | ||
| B) | is highest in the 20 to 49 age-group. | ||
| C) | does not vary according to food source or serotype. | ||
| D) | is the second-highest among bacteria-related foodborne illnesses. |
Salmonella infection, or salmonellosis, is second only to Campylobacter among the leading causes of bacterial foodborne disease. According to preliminary FoodNet data for 2023, the incidence was 16.6 per 100,000 [2]. Compared with 2016–2018, the 2023 reported incidences of S. enterica serotypes Enteritidis and Newport remained stable, whereas the incidences of Typhimurium and Javiana serotypes decreased substantially [2]. Salmonella remains the most common cause of outbreak-related foodborne illness, accounting for 644 reported outbreaks in 2023 [2].
| A) | meningitis. | ||
| B) | reactive arthritis. | ||
| C) | irritable bowel syndrome. | ||
| D) | Guillain-Barré syndrome. |
Acute Campylobacter infection may cause intestinal hemorrhage, toxic colitis, meningitis, bacteremia, and HUS [69]. HUS is characterized by renal impairment, microangiopathic hemolytic anemia, and thrombocytopenia and most frequently affects children with campylobacteriosis [34,69]. Other potential long-term complications of campylobacteriosis include reactive arthritis (1% to 7%), irritable bowel syndrome (25%), and Guillain-Barré syndrome (0.1%) [69,129,130]. The mortality rate associated with campylobacteriosis is 0.1% [34].
| A) | Pregnant women are at low risk for listeriosis. | ||
| B) | The mortality rate associated with listeriosis is less than 15%. | ||
| C) | The incidence of listeriosis has increased since the early 2000s. | ||
| D) | Gastrointestinal symptoms usually begin within 9 to 48 hours after ingestion of contaminated food. |
Since 2000, the incidence of listeriosis has decreased considerably, by 34% between 1989 and 1993, by 36% from 1996 to 2006, and by 26% from 2014 to 2016 [2,133]. In 2008, 33 individuals were affected by three confirmed outbreaks [66]. In 2017, 8 confirmed foodborne listeriosis outbreaks resulted in 32 illnesses, and 31 hospitalizations [3]. In 2011, health officials in Colorado notified the CDC of seven cases of listeriosis associated with consumption of cantaloupe from the same farm [146]. In 2023, CDC surveillance recorded 163 Listeria infections, leading to 159 hospitalizations and 36 deaths [2].
Pregnant women are at high risk for the disease, but symptoms are nonspecific and diagnosis is difficult [147]. Maternal infection leads to premature birth or spontaneous abortion in many cases [34,148,149]. The mortality rate associated with Listeria infection is approximately 20% to 30% [94,95].
Ubiquitous in the environment, Listeria is found in many species of mammals (particularly herd animals), birds, and marine life [34,69]. Contaminated soil or water can cause contamination of fruits and vegetables or farm animals. Raw (unpasteurized) milk is a primary source. As many as 10% of humans are carriers of the pathogen [34].
Foodborne listeriosis often begins with fever, muscle aches, nausea, and possibly diarrhea; gastrointestinal symptoms usually begin within 9 to 48 hours after ingestion [21]. In pregnant women, infection usually manifests as mild flu-like symptoms [21]. Potential complications include bacteremia and meningitis [21]. Listeriosis-related meningitis is associated with a mortality rate of approximately 70% [34]. Invasive disease typically manifests 2 to 6 weeks after ingestion [21].
| A) | Refrigeration destroys Yersinia. | ||
| B) | Symptoms of yersiniosis differ according to age. | ||
| C) | Muscle aches are a common symptom of yersiniosis. | ||
| D) | Yersinia is often transmitted through contaminated water. |
Pigs are the primary reservoirs for Yersinia [155]. However, humans may be carriers for several months after infection [69,155]. Commonly associated foods are raw/undercooked pork, oysters, fish, unpasteurized milk, and ice cream [34,69]. The organism can grow at 4°C, which means that refrigerated meats can be sources of infection [34,132]. Waterborne infections are rare [69].
Symptoms associated with Yersinia infection usually occur within 24 to 48 hours after ingestion of contaminated food [21]. The clinical presentation of yersiniosis is age-specific. In infants and young children, mucoid diarrhea with blood and leukocytes, as well as fever, is common, whereas in adolescents and adults, an appendicitis-like syndrome (i.e., diarrhea, vomiting, fever, abdominal pain) usually occurs [34,69]. Yersinia enterocolitica may lead to reactive arthritis in 2% to 3% of individuals with infection, even in the absence of obvious symptoms [34,69]. Bacteremia is a potential complication among children with excessive iron storage or who have compromised immune systems [69].
| A) | The mortality rate associated with botulism is approximately 25%. | ||
| B) | Foodborne botulism is more common than infantile botulism. | ||
| C) | The incidence of foodborne botulism in Alaska remains more than 800 times the overall U.S. rate. | ||
| D) | None of the above |
The incidence of foodborne botulism in Alaska remains more than 800 times the overall U.S. rate [159]. Approximately 27% of all foodborne botulism cases in the United States have occurred in that state [160]. Between 1950 and 2016, 200 outbreaks (366 cases; 303 confirmed, 63 suspected) of foodborne botulism were recorded in Alaska and involved Alaska Natives [160,161]. In 2016, 205 confirmed cases of botulism were reported to the CDC, with foodborne botulism accounting for 29 of the cases (14%) [162]. Infant botulism was more common than foodborne botulism, with 150 cases (73%) reported in 2016 [162]. Most cases of infant botulism have occurred in breastfed babies when nonhuman-milk foods were introduced [69,119]. The rate of mortality associated with the disease is approximately 5% [133].
| A) | Bacillus cereus is most often associated with fruit. | ||
| B) | Bacillus cereus is heat resistant and can survive cooking. | ||
| C) | Symptoms of Bacillus cereus often persist for one to two weeks. | ||
| D) | The onset of symptoms is more rapid with the diarrheal type of Bacillus cereus infection than with the emetic type. |
Bacillus cereus food poisoning is transmitted through ingestion of contaminated food, and there is a broad range of potential food sources, including meats, milk, vegetables, and fish (diarrheal-type illness) and rice products and other starchy foods, such as potato, pasta, and cheese products (emetic-type illness) [34]. Bacillus cereus occurring in grains and beans was the pathogen-food category pair responsible for the most illnesses in outbreaks [3]. Outbreaks also have often involved food mixtures, such as sauces, puddings, soups, casseroles, and pastries. Bacillus cereus is heat resistant and can survive cooking (even at recommended temperatures). In addition to contaminated food, transmission of infection can also occur with improper food handling or storage; person-to-person transmission is rare [34].
The symptoms caused by the diarrheal type of Bacillus cereus food poisoning are similar to those of Clostridium perfringens infection. Symptoms include watery diarrhea and abdominal cramps that may be accompanied by nausea but usually not vomiting. The onset of symptoms is typically 6 to 16 hours after ingestion of contaminated food [21,34]. Symptoms usually resolve within 24 to 48 hours [21].
The enteric type of Bacillus cereus food poisoning causes symptoms similar to those associated with foodborne Staphylococcus aureus infection. The onset of nausea and vomiting occurs within one to six hours after ingestion of contaminated food and may be accompanied by diarrhea and/or abdominal cramps [21,34]. Symptoms usually resolve within 24 hours.
| A) | occurs most often in Alaska. | ||
| B) | causes abrupt onset of symptoms. | ||
| C) | is usually transmitted through person-to-person contact. | ||
| D) | is most commonly traceable to dairy products from infected animals. |
Brucellosis is rare in the United States, with an incidence of less than 0.5 per 100,000 [44]. Most cases are caused by Brucella melitensis, the majority of which are reported from California, Florida, Texas, and Arizona [166]. There were no foodborne outbreaks of Brucella reported in 2017 [3].
In the United States, most human infection is acquired by direct contact with infected livestock or animals harboring Brucella, or by consumption of undercooked game meat or contaminated milk and dairy products (133; 166]. Transmission through person-to-person contact is extremely rare. Animals harboring Brucella infection and susceptible to human contact include cattle, sheep, goats, pig, bison, moose, moose, elk, and caribou [166]. Occupational exposures occur among slaughterhouse workers, hunters, veterinary staff, animal shelter staff, and microbiology laboratory personnel.
Symptoms typically occur 7 to 21 days after ingestion of contaminated food [21]. The clinical presentation of brucellosis is nonspecific and includes fever with chills, sweating, malaise, headache, and myalgia as well as diarrhea, which may be bloody during the acute stage of disease [21]. Symptoms may last for weeks. Meninges, bone, and/or the heart may be involved, which can lead to such complications as meningitis, osteomyelitis, and endocarditis [69,166]. Disease is usually more severe in adults than in children [69].
| A) | It does not usually cause vomiting. | ||
| B) | It is best diagnosed with microbiologic testing. | ||
| C) | It can occur from ingesting improperly stored foods. | ||
| D) | It is characterized by diarrhea occurring one to two days after ingestion of contaminated food. |
Staphylococcus aureus is transmitted through person-to-person contact, usually as a result of a food handler who is infected with the bacteria [133]. The bacteria will multiply on improperly stored foods, especially pastries, custards, salad dressings, cheeses, meat products, and expressed human milk [69,133]. Staphylococcal toxins are resistant to heat and cannot be destroyed by cooking [133].
Staphylococcal food poisoning is characterized by the rapid onset of nausea and vomiting, which may occur within 30 minutes of ingestion (range: 1 to 6 hours) [21,133,167]. Other symptoms include abdominal pain, diarrhea, and fever [21,167]. The disease is usually mild, with recovery within 1 to 3 days [21,133].
Staphylococcus aureus toxins can be identified from stool, vomitus, and food, but microbiologic testing is not usually done [21,167]. Staphylococcal enterotoxin B is classified as a category B bioterrorism agent and is nationally notifiable [133].
| A) | Norovirus is the most common cause of foodborne gastroenteritis in the United States. | ||
| B) | Vaccination against norovirus is recommended as children reach the age of eating in public. | ||
| C) | Norovirus accounts for almost half of all reported foodborne outbreaks caused by a single identified pathogen. | ||
| D) | Food handlers are a common source, and acquisition of infection is associated with eating in restaurants. |
Norovirus is the leading cause of gastroenteritis and foodborne disease outbreaks in the United States. About 50% of all outbreaks of food-related illness are caused by norovirus [174]. Most of these outbreaks occur in food-service settings. Infected food workers are frequently the source of outbreaks, often by touching ready-to-eat foods with their bare hands before serving them. Norovirus outbreaks can also occur from food contaminated at the source, such as oysters harvested from contaminated waters or fruit and vegetables sprayed with contaminated water in the field. According to estimates derived from surveillance data, norovirus causes 2 million illnesses, 56,000 to 71,000 hospitalizations, and 570 to 800 deaths annually [172]. In 2017, norovirus was the most common cause of confirmed single-etiology foodborne outbreaks, accounting for 140 (35%) outbreaks and 4,092 (46%) illnesses; moreover, it was the suspect etiologic agent for an additional 177 outbreaks and 2,140 food-related illnesses [3]. The incidence of norovirus infection increases during the winter months, and periodic outbreaks tend to occur in association with the emergence of new GII strains that evade population immunity [171].
In 2009, the CDC launched CaliciNet, an outbreak surveillance network for noroviruses in the United States [173,174]. The CDC uses the information to link norovirus outbreaks, monitor trends, and identify emerging strains. As of 2018, 34 laboratories in 29 states and the District of Columbia have been certified by the CDC to participate in CaliciNet [175].
Between 2009 and 2012, norovirus was the etiologic pathogen identified in 1,008 foodborne outbreaks, accounting for 48% of all reported outbreaks with a single known cause [176]. Eating in restaurants was the most common setting (65%), and food handlers were implicated as the source in 70% of outbreaks in which factors contributing to contamination could be identified. Other factors included contamination of food during preparation (92%) and consumption of raw food (75%) [176]. Specific food categories were implicated in only 67 outbreaks, the most frequent being leafy vegetables (30%), fruits (21%), and mollusks (19%) [176].
Foodborne infection with either norovirus or sapovirus is transmitted via the fecal-oral route through infected food handlers, exposure to contaminated surfaces, consumption of contaminated food, or rarely, ingestion of contaminated water [171,176,177]. Aerosolized norovirus particles in vomitus can also contribute to spread of the disease, and these particles can travel a distance of up to 3 feet [177,178,179]. The most common sources are prepared foods (e.g., sandwiches, salads) and raw produce [84].
| A) | is rare in the United States. | ||
| B) | is characterized by inflammatory diarrhea. | ||
| C) | causes symptoms within a few hours of infection. | ||
| D) | should not be ruled out on the basis of one negative microbiologic test. |
Prevalence studies show 2% of the population of North America harbors Cryptosporidium in the gastrointestinal tract; serologic surveys indicate that 80% of the population has had a past infection [34]. Two confirmed outbreaks of foodborne infection with Cryptosporidium were reported in 2017, affecting 12 individuals [3]. The incidence of Cryptosporidium was 3.7 per 100,000 in 2017, ranking it fourth among the infectious foodborne pathogens monitored in the FoodNet program [2]. Rates of cryptosporidiosis peak strongly in the late summer [123].
Foodborne acquisition of cryptosporidiosis usually occurs by way of an infected food handler [21]. Animals raised for food may also serve as vehicles for transmission, and the parasite most commonly infects herd animals (e.g., cows, goats, sheep) [34]. Fresh produce may also become contaminated [34].
Infection with Cryptosporidium causes noninflammatory, profuse watery diarrhea lasting up to two to three weeks, often accompanied by stomach cramps, nausea and vomiting, slight fever, anorexia, and weight loss [21,185]. Some individuals may be asymptomatic [69,185]. The onset of symptoms is usually within 2 to 10 days [21,185]. Although infection is self-limiting in otherwise healthy individuals (10 to 14 days), it can become chronic in individuals with compromised immune systems [185].
A confirmed case requires evidence of Cryptosporidium organisms or DNA in stool, intestinal fluid, or tissue samples. Light microscopy of stained specimens is a common means of testing; other methods include direct florescent antibody (DFA) test, enzyme immunoassay (EIA), and polymerase chain reaction (PCR) [69,186]. These tests must be ordered specifically [21]. Because shedding may be intermittent, three stool samples collected on different days should be tested before suspected cryptosporidiosis can be ruled out [69]. Cryptosporidium infection is a nationally notifiable disease.
| A) | Cyclospora infection occurs most often in cooler climates. | ||
| B) | Antimicrobial therapy is not recommended for cyclosporiasis. | ||
| C) | Washing of contaminated produce does not eliminate the risk of transmission. | ||
| D) | Transmission of cyclosporiasis is most likely through person-to-person contact. |
Cyclosporiasis occurs most commonly in tropical and subtropical areas [97,184]. The disease is not known to be endemic in the United States; however, since 1990, multiple foodborne outbreaks of cyclosporiasis, affecting thousands of individuals, have been documented in the United States and Canada [184,187,188]. Most reported illnesses arise in the spring and summer months. During the period of 1997–2008, the CDC was notified of 1,110 laboratory-confirmed cases of sporadic cyclosporiasis, occurring in 37 states, including seven in which cyclosporiasis is not an explicitly reportable disease. More than one-third of the case-patients had a documented history of international travel [97]. In 2009, 141 cases of Cyclospora were reported to the CDC [187]. In 2023, FoodNet surveillance identified 367 cases of Cyclospora foodborne disease, of which 39 isolates were outbreak-associated, for an incidence rate of 0.7 per 100,000 persons [2]. Throughout 2023, CDC identified 2,272 cases of cyclosporiasis nationwide; onset of illness in all cases was between April 1 and August 31, 186 were hospitalized (no deaths) [187].
In 2018, multiple outbreaks of cyclosporiasis (2,299 confirmed cases) linked to produce items were reported to the CDC from 33 states [188,189]. Approximately one-third of the illnesses were associated with one of two large multistate outbreaks in the Midwest: one outbreak involved prepackaged vegetable trays (broccoli, cauliflower, carrots) sold at a convenience store chain; and one involved salads (carrots, romaine, spinach, kale, red leaf lettuce) sold at a fast food chain. Additional clusters were associated with basil and cilantro. Two basil-associated clusters of 8 confirmed cases were identified in two states in the West and Midwest. Multiple cilantro-associated clusters were identified, including three associated with unrelated Mexican-style restaurants in the Midwest. The CDC received reports of 53 confirmed cases associated with these three clusters [189].
Individuals become infected with Cyclospora by ingesting oocysts that have become environmentally contaminated [187]. Direct person-to-person transmission of Cyclospora is unlikely because shed oocysts are noninfectious [184]. Washing of contaminated produce decreases, but does not eliminate, the risk of transmission [69]. A large outbreak of Cyclospora on imported raspberries demonstrates the potential risk for transmission from contaminated water or infected food handlers [51].
The onset of symptoms of cyclosporiasis is typically at least 1 week after ingestion of contaminated food (range: 2 to 14 days) [21,187]. Symptoms include profuse, usually watery diarrhea, loss of appetite with resultant weight loss, stomach cramps, nausea and vomiting, and fatigue [21,187]. Illness may become persistent (10 to 12 weeks) and relapsing if left untreated [21,187].
Oocysts can be detected in stool samples, but testing must be specifically requested [21,187]. Cyclosporiasis is a nationally notifiable infection. The recommended treatment is oral TMP-SMX for 7 to 10 days [21,184,187].
| A) | Ciguatera | ||
| B) | Scombroid | ||
| C) | Domic acid | ||
| D) | Tetrodotoxin |
Different types of blooms occur in various geographic locations in the United States, and the toxins produced differ according to the bloom (Table 12) [194]. Pyrodinium bahamense from harmful algal blooms have caused toxic pufferfish exclusively in the waters off the coast of Florida. Another toxin, tetrodotoxin, is also found in pufferfish, but in species that inhabit the shallow waters of the temperate and tropical zones [195]. These fish (e.g., ocean sunfishes, porcupine fishes, pufferfish [fugu]) are considered to be a delicacy in some cultures but are the most poisonous of all marine life [196]. Tetrodotoxin is among the most potent poisons known [197; 198].
| A) | Dizziness | ||
| B) | Bradycardia | ||
| C) | Abdominal pain | ||
| D) | Reversal of temperature sensations |
Gastrointestinal symptoms (e.g., diarrhea, vomiting, abdominal pain) occur in more than 50% of individuals within 2 to 6 hours after ingestion of the toxin and may last 1 to 2 days; neurologic symptoms, which include reversal of temperature sensations, distal and perioral numbness and/or tingling, and dizziness, usually occur within a few hours to 3 days and can be persistent, lasting weeks to several months [21,201,202]. Within 2 to 5 days, cardiovascular symptoms (less common but potentially severe), such as bradycardia, hypotension, and T wave abnormalities, may appear [21,202].
| A) | Amnesic shellfish poisoning | ||
| B) | Diarrheic shellfish poisoning | ||
| C) | Neurotoxic shellfish poisoning | ||
| D) | All of the above |
Symptoms of neurotoxic shellfish poisoning occur within a few minutes to 3 hours. The toxin (e.g., brevetoxin) causes both gastrointestinal and neurologic symptoms, generally mild and self-limited [193,211]. Gastrointestinal symptoms may include diarrhea and vomiting. Neurologic symptoms may include tingling and/or numbness of the lips, tongue, and throat; muscle aches; dizziness; and reversal of temperature sensations [21,193,212]. Neurotoxic shellfish poisoning is the least common of the shellfish poisonings and is less severe than ciguatera poisoning. Recovery is complete within hours to 2 to 3 days [21,201]. No fatalities have been reported [211].
| A) | Complete recovery within 2 to 6 days | ||
| B) | Spontaneous recovery within 5 to 24 hours | ||
| C) | Alternating periods of drowsiness and excitement for several hours, followed by complete recovery | ||
| D) | Apparent recovery within a few hours, followed by a symptom-free period of 3 to 5 days, and subsequent coma and death |
DIAGNOSIS OF MUSHROOM POISONINGS ACCORDING TO SYMPTOMS AND THEIR ONSET
| Symptoms | Onset | Cause | Disease Course |
|---|---|---|---|
| Nausea, abdominal discomfort (sometimes with diarrhea and vomiting) | 15 minutes to 2 hours | Unknown toxins (from numerous genera) | Rapid and complete recovery; severe illness may cause symptoms to last 2 to 3 days and require fluid replacement |
| Excessive sweating, lacrimation, salivation | 15 to 30 minutes | Muscarine | Complete recovery within approximately 2 hours; death is rare but may result from cardiac or respiratory failure |
| Inebriation or hallucinations without drowsiness or sleep | 15 minutes to 2 hours | Psilocybin | Complete and spontaneous recovery occurs within 5 to 10 hours; if large amount of toxin ingested, recovery may take up to 24 hours; more severe in children |
| Delirium with sleepiness or coma | 1 to 2 hours | Ibotenic acid/muscimol | Alternating periods of drowsiness and excitement occur for several hours, followed by total recovery |
| Feeling of abdominal fullness, severe headache, vomiting (no diarrhea) | 6 to 10 hours | Gyromitrin | Complete recovery occurs within 2 to 6 days; correction of metabolic acidosis may be required; some deaths have occurred as a result of liver failure |
| Persistent and intense vomiting; abdominal pain; profuse, watery diarrhea | 6 to 12 hours | Amanitin | Apparent recovery occurs a few hours after onset of symptoms, followed by a symptom-free period of 3 to 5 days, and subsequently by a period of jaundice, loss of strength, coma, and often death |
| Intense, burning thirst and frequent urination, followed by gastrointestinal disturbances, headache, pain in the limbs, spasms, and loss of consciousness | 3 to 21 days | Orellanine | Recovery (including recovery of renal function) may require several months in cases of less severe poisoning; death from kidney failure may occur in cases of severe poisoning |
| Flushing; palpitations; rapid heartbeat; rapid, labored breathing within 30 minutes to 2 hours after consuming alcohol | Within 72 hours | Coprine | Recovery is spontaneous and complete within a few to several hours after onset of symptoms |
| A) | Giardia | ||
| B) | Rotavirus | ||
| C) | Norovirus | ||
| D) | Cyclospora |
Vaccines have been developed for two viruses that can be transmitted through food: rotavirus and hepatitis A. Two vaccines are now available for rotavirus: RV5 (RotaTeq) was approved for use in 2006, and RV1 (Rotarix) was approved in 2008. The American Academy of Pediatrics recommends routine vaccination with either vaccine, without noting a preference for either one [225]. RV5 is given orally in a three-dose series, at 2, 4, and 6 months of age. RV1 is given orally in a two-dose series, at 2 and 4 months of age [225]. Studies have shown that the vaccines provide 85% to 95% protection against severe rotavirus and 74% to 87% protection against any rotavirus illness [225,226].