Introduction to Foodborne Diseases
How many people inspect cans in the grocery store for bulging ends? The historical story of botulism in canned foods that began in 1919, especially olives and green beans, impacts what some people do a century later. At the time, sensational journalism claimed, “one drop…would depopulate the Earth”. Many changes were made to the commercial canning industry through both voluntary and governmental changes that improved food safety. It is a reminder that knowledge and actions are necessary to keep the food supply safe and involves both the individual and the surveillance and regulation of foodborne illnesses (Kazanjian, 2018).
Epidemiologic Resources in the US for Foodborne Disease
According to the Centers for Disease Control and Prevention (CDC, 2018b), there are 250 foodborne diseases. Bacteria, viruses, and parasites cause many of the foodborne infections, but toxins and chemicals in food can also cause disease. The five most common foodborne disease agents in the US are Norovirus, Salmonella, Clostridium perfringens, Campylobacter, and Staphylococcus aureus. The microorganisms most likely to result in hospitalization are Clostridium botulinum, Listeria monocytogenes, Escherichia coli (E. coli), and Vibrio. The CDC (2019e) estimates that 48 million people get sick, 128,000 are hospitalized, and 3,000 people die annually from foodborne disease. Foodborne disease affects approximately one in every six people each year (Boyce, 2018). The standard that is increasing in use to determine the impact of foodborne pathogens is the disability-adjusted life year (DALY). This combines loss of life and decreased health because of illness compared with an ideal state of health, using time as the common measure (O’Brien, 2017).
Access to current information and referral for patients at risk for, or experiencing foodborne disease is a nursing responsibility. CDC is the governmental agency that is responsible for surveillance, investigations, and implementation of protocols for prevention, identification, and eradication of foodborne disease outbreaks. Case reporting to the CDC is voluntary for most diseases if a single location is involved. Reporting occurs through the National Outbreak Reporting System. State health departments also may have access to provide specific DNA identification, especially for Salmonella, Shigella, Listeria, and Shiga toxin-producing E. coli (STEC). Other resources involved in foodborne disease reporting include OutbreakNet Enhanced, which assists state health departments during outbreaks and identifies gaps in investigation. FoodCORE, with regional locations for response to outbreaks; and the Integrated Food Safety Centers of Excellence, which provides training and information to state and local health departments within regions and through university partners in Colorado, Florida, Minnesota, New York, Oregon, and Tennessee (CDC, 2018c). The Food and Drug Administration (FDA, 2018a) monitors foodborne organisms that occur from any food product, agricultural or commercial, that are regulated by governmental standards.
When two or more people get the same illness from the same contaminated food or drink, it is determined to be an outbreak by the CDC. They maintain records on multistate outbreaks. Examples of multistate outbreaks in 2019 include:
- Salmonella: pig ears as dog treats, papayas, tahini, frozen raw tuna, pre-cut melon, and ground turkey.
- E. coli: bison, flour, and ground beef.
- Listeria monocytogenes: deli-sliced meats and cheeses.
- Cyclospora: basil from Mexico.
- Multiple organisms: raw oysters. (CDC, 2019a)
This list is a reminder of the variety of foods that can transmit disease.
Figure 1 (below) from the CDC outlines the steps of the management of a foodborne disease outbreak.
Figure 1. CDC Outbreak Investigation Process
General Symptoms of Foodborne Disease
Gastroenteritis is the general term applied to the symptoms of any disease affecting the gastrointestinal tract. Infectious foodborne diseases are the most common cause (Boyce, 2018). Primary symptoms are diarrhea and/or vomiting. Diarrhea is defined as three or more loose or liquid stools a day. Acute diarrhea lasts less than 14 days, while chronic diarrhea lasts more than 14 days (Lewis, Bucher, Heitkemper, & Harding, 2017). Prolonged or frequent vomiting can deplete intravascular fluid, causing tachycardia, and, eventually hypotension. Acid-base balance is affected, with vomiting more likely to result in metabolic alkalosis and diarrhea, more commonly resulting in metabolic acidosis. Both can cause hypokalemia. In the following information about the specific foodborne diseases, characteristics of varying degrees and severity of vomiting and diarrhea are described. It is important to teach patients to recognize which symptoms can be managed by home treatment and which require medical treatment (Boyce, 2018).
Foodborne diseases are usually acute illnesses that last less than a week. Many people do not seek treatment (National Institutes of Health [NIH], 2019). A challenge with foodborne disease is that health providers do not see many of those affected by the disease. Sometimes it is days or, in some cases, years after the infection that the patient may seek treatment (Kang & White, 2016). The most common symptoms are the sudden onset of diarrhea, nausea, vomiting, abdominal cramping, and fever (Lewis et al., 2017). Symptoms that indicate a need for medical intervention include bloody stools, high fever >1020 F, prolonged vomiting or inability to keep down liquids, diarrhea for more than three days, and severe dehydration with decreased urination or postural hypotension (CDC, 2019b). The most common acute complication is dehydration. Additional risks occur when a foodborne illness occurs during pregnancy and can result in miscarriage or stillbirth (NIH, 2019). Long-term complications include chronic arthritis, hemolytic uremic syndrome, and brain or nerve damage (CDC, 2019b).
Groups at Increased risk of Foodborne Disease and Complications
Several groups of people are more at risk of foodborne illness. Those at the most significant threat from gastrointestinal infections are young children. Dehydration from diarrhea and vomiting is the immediate physiologic challenge, but the infection may also damage the gut resulting in nutritional and developmental deficiencies (Kang & White, 2016). Young children with Salmonella are three times more likely to be hospitalized. In children under the age of five with E. coli 0157 infections, one out of seven develops kidney failure. Worldwide, gastroenteritis currently results in the death of approximately 1.5 million children annually, but this about one-quarter to one-half of the previous death rates in children. While much credit is given to improved water sanitation, oral rehydration for infants has also improved outcomes. Rotavirus, the most common viral foodborne infection in children, has decreased in incidence in the US by 80% since the implementation of routine immunization (Boyce, 2018).
People over 65 years of age are at higher risk due to decreased immunity. Hospitalization is necessary for approximately half of people over 65 with Salmonella, Campylobacter, Listeria, or E. coli (CDC, 2019d). Older patients are more likely to have cardiac compromise or renal insufficiency that increase the risk for fluid and electrolyte imbalance that is exacerbated by infectious disease. If the older adult has decreased consciousness, the risk for aspiration during vomiting related to the foodborne disease goes up. Antiemetics with central nervous systems side effects present additional risks to older clients. Use the lowest effective dose of antiemetics in older patients, as the risks for falls increases due to dehydration and medication side-effects (Lewis et al., 2017). The use of hypotonic fluids in replacement therapy can increase the risk of hyponatremia (Boyce, 2018). The immunocompromised state of patients with diabetes, liver disease, kidney disease, HIV/AIDS, alcoholism, and cancer increases the risk and severity of foodborne disease. Listeria is 50 times more likely in people on dialysis (CDC, 2019d).
Diagnostic Testing for Foodborne Disease
The classic diagnostic testing in foodborne disease with gastroenteritis has been stool cultures. A stool culture is not routinely performed but is indicated by diarrhea for more than three days, in the presence of high fever, or extreme illness. The stool may also be examined for blood, mucus, white blood cells, parasites, or for the presence of specific toxins. If diarrhea lasts for more than two weeks, the stool may also be examined for ova and parasites (Lewis et al., 2017). Subacute, chronic watery diarrhea indicates a need for parasitic testing. Acute diarrhea with gross blood indicates a need for stool culture for E. coli 0157:H7. This test requires a specific request since it is not part of a standard stool culture. Other indications for stool testing include immunosuppression, exposure to a known outbreak, recent travel, or recent antibiotic use. Polymerase chain reaction (PCR) testing of stool can detect subtypes of organisms and is especially useful for E. coli subtypes (Boyce, 2018). This rapid diagnostic testing (RDT) of stool identifies up to 22 common pathogens, which include bacteria, viruses, and parasites within an hour of sample preparation. While this testing is expensive, it may reduce the total number of tests for the patient and allow for the appropriate medication treatment to begin earlier. Diagnostic stewardship in the use of RDT necessitates a high-quality assessment of history by health care providers and nurses to ensure that symptoms of infectious diarrhea are present (Qasmieh, Quinn, & Ries, 2018).
Other diagnostics tests in foodborne disease include serum testing for blood urea nitrogen (BUN), creatinine, electrolytes, and acid-base evaluation. A complete blood count (CBC) is usually non-specific, but in parasitic infections, eosinophilia is found. Renal function tests, along with a CBC, should be initiated in foodborne disease with risk for hemolytic-uremic syndrome. With E. coli 0157:H7, where onset begins early, renal testing should begin one week after the onset of symptoms. Another test specific to E. coli 0157:H7 is a rapid enzyme assay for the detection of Shiga toxin in the stool. This potent toxin produced by bacteria breaks down tissues, especially in the kidney. White blood cells in stool are more common in enteric pathogens, including Salmonella, Shigella, Campylobacter, and E. coli, and diarrhea does not usually include gross blood. A sigmoidoscopy with culture and biopsy is indicated in adults with grossly bloody diarrhea to evaluate mucosal changes that differentiate the diagnosis of amebic dysentery, shigellosis, or E. coli 0157:H7 (Boyce, 2018).
An added tool in investigating outbreaks is strain typing. Traditionally, a procedure known as pulse-field gel electrophoresis (PFGE) has been used. Still, the newer techniques of matrix-assisted laser desorption/ionization-time of flight mass-spectrometry and whole-genome sequencing are improved processes. Whole-genome sequencing has only recently become rapid and affordable. While these tools are useful in outbreaks, limited personnel with expertise in the technology, along with cost reimbursement when the benefit is to a population, rather than an individual, remain challenges (Lee, 2017).
The spread of foodborne diseases is also a possibility in the hospital setting as part of diagnostic tests. Nosocomial Salmonella infections occurred when decontamination was inadequate of an endoscope after endoscopic retrograde cholangiopancreatography. Adequate training and familiarity with the specific equipment used are essential to prevent similar transmissions of organisms (Robertson et al., 2017).
Infectious Foodborne Diseases of the US
The CDC (2018a) ranks the most common foodborne illnesses each year (see Table 1 below). In this article, the infectious foodborne diseases are initially ranked by their occurrence, hospitalization, and mortality rates and then described in detail. They identify the top five in each category. The remaining portion of the article describes other foodborne diseases, differentiated first by reportability and then by either occurrence or risk. The non-reportable diseases are grouped by causative organism: bacteria, viruses, and parasites.
Table 1. The Leading Foodborne Pathogens in the US
Top five pathogens contributing to domestically acquired foodborne illnesses.
Top five pathogens contributing to domestically acquired foodborne illnesses resulting in hospitalization.
Top five pathogens contributing to domestically acquired foodborne illnesses resulting in death.
The most common foodborne disease in the US and globally is Norovirus (NoV) (CDC, 2018a; Iturriza-Gomara & O’Brien, 2016). Current CDC (2019e) reports estimate 20.8 million cases annually with 56,000 hospitalizations and 149 deaths. The latest global data from the World Health Organization reported 125 million total cases, and 35,000 deaths attributed to NoV infections. This viral infection is spread predominately by human feces and vomit. Environmental contamination by virus particles can last from several days to months. Norovirus is highly infectious, and neither future protection nor cross-protection from other genotypes occurs subsequently. Susceptibility to NoV infection and disease is related to the expression of histo-blood group antigens (HBGAs) as NoV binds to HBGAs. Binding of NoV to animal cells, especially oyster guts, and a NoV-like particle that binds to HBGA-like carbohydrates in the cell wall of lettuce have been identified. Infected food handlers, both symptomatic and asymptomatic, have been identified as sources. The current recommendation is handwashing with soap since alcohol-based hand sanitizer is not as effective in eliminating NoV. An estimated 14% of NoV infections result from the ingestion of contaminated food. Fresh produce and oysters are the two most common foods, but food handlers are also a source. Binding of the NoV to bacteria occurs in the human microbiome and foods, leading to the protection of the NoV during food processing treatments (Iturrize-Gomara & O’Brien, 2016). Viruses, such as norovirus, usual affect the villi of the small bowel and result in more fluid and electrolytes moving into the lumen of the bowel (transudation), causing watery diarrhea. The predominant symptom of NoV in adults is diarrhea, while in children, vomiting is more common. Fever may occur, and the patient may also report abdominal cramping, headache, and muscle pain (Boyce, 2018).
Salmonella causes two different foodborne diseases: non-typhoidal and typhoid fever. Salmonella (nontyphoidal) causes approximately 1.2 million illnesses, 19,000 hospitalizations, and 378 deaths in the US annually. Salmonella enterica serotype Typhi (typhoid fever) is estimated to cause 5,700 illnesses, 1600 acquired in the US) with (CDC, 2019e) with 600 cases hospitalized and no deaths (CDC, 2019e). Incidence increases in the summer months. Children under five, non-breastfed infants, adults over 65, people who are immunocompromised, and those who take certain medications, especially those that reduce stomach acid, are more at risk (CDC, 2019f). The Netherlands experienced the most significant foodborne outbreak worldwide (within one country), with laboratory confirmation of 1,149 cases of Salmonella in 2012 from smoked salmon (Suijkerbuijk et al., 2016).
Nontyphoidal salmonellosis has a mortality of less than 1% but is highly infective with a single bacteria of some strains sufficient to initiate disease. The onset of symptoms begins 6 - 72 hours after exposure, with the duration of acute symptoms usually lasting one to two days. Symptoms resolve after four to seven days, but the dose and strain may alter severity and duration (FDA, 2012). The organism may be shed in the stool for several weeks after infection (CDC, 2019f). Typical symptoms include nausea, vomiting, abdominal cramps, diarrhea, fever, and headache. Complications occur most often in the high-risk groups with dehydration and electrolyte balance a significant risk. Sequelae include reactive arthritis, an autoimmune disorder occurring three to four weeks after infection and septicemia or bacteremia that affects other internal organs and tissues (FDA, 2012). Extra-intestinal, invasive Salmonella infection can affect the bone (osteomyelitis), joints (septic arthritis), brain, and nervous system (meningitis). Antibiotics are not generally used in treatment but are indicated for severe illness or high-risk patients (CDC, 2019).
Typhoid fever, caused by S. typhi and S. paratyphi, has a mortality rate of 10% if untreated. These two species of Salmonella are only found in human hosts; thus, foods contaminated with human feces are the primary risk factor. Fewer than 1,000 cells are needed to cause infection. Onset is usually within one to three weeks but may be as long as two months after exposure. Symptoms include a high fever (103 – 104°F), lethargy, abdominal pain, diarrhea or constipation, headache, general aching pain, anorexia, and occasionally, a flat, rose-colored, spotty rash. Complications include septicemia that may lead to endocarditis, septic arthritis, or chronic infection of the gallbladder. Chronic infection of the gallbladder could lead to the person becoming a carrier (FDA, 2012). Intestinal perforation, neurologic involvement, and death may occur following systemic infection (Dekker & Frank, 2015).
Both forms can be foodborne but can also be transmitted via fecal particles or contaminated water. Traditionally, Salmonella is associated with meat, especially chicken. Currently, more cases are attributed to fresh produce; even dry foods, such as spices, have been the vehicles for outbreaks. The list of linked foods is extensive. It goes well beyond eggs and dairy products to include yeast, coconut, cake mixes, cream-filled desserts, dried gelatin, peanut butter, cantaloupes, tomatoes, and chocolate. While testing of food includes rapid antibody and molecular-based assays, currently, the presence of Salmonella on culture is required to meet regulatory standards for confirmation (FDA, 2012).
Non-pathogenic Clostridium perfringens are common in the environment and the human digestive system. Clostridium perfringens replicates quickly and once in the small intestine begins to make an enterotoxin. C. perfringens type A contains the CPE (carboxypeptidase-E) gene that causes food poisoning from the toxin. Less frequently, types B, C, D, and E contain the CPE gene. CPE gene works mainly in the small intestine. It results in the activation of proteins that occur with the release of enterotoxins as well as increasing loss of fluid and electrolytes (FDA, 2012). Clostridium perfringens in food usually results in mild self-limiting diarrhea. Abdominal cramps and watery diarrhea are the most common symptoms. Symptom onset is typically 6 - 24 hours after eating the contaminated food. It is unusual to have vomiting or fever. Resolution usually occurs within 24 hours. Hospitalization is rarely required, and it is rarely fatal (Bush & Vazquez-Perteho, 2018a).
In some cases, watery diarrhea can cause significant fluid loss and electrolyte imbalance with a risk for cardiac dysrhythmias in some clients (FDA, 2012). Another risk is damage to the small bowel with a risk of perforation. While rare, perforation can be fatal (Bush & Vazquez-Pertejo, 2018a).
A second foodborne disorder from C. perfringens, enteritis necroticans (Pig-bel form), occurs internationally but is rare in the US. It is more severe and often fatal. Along with abdominal pain, vomiting, and diarrhea, the patient may experience abdominal distention, gassy bloating, and bloody diarrhea. The organism produces a beta toxin that causes necrosis in the bowel. The beta toxin is trypsin-sensitive, and adequate levels of trypsin contribute to the resolution of the disease. Food known to inhibit trypsin is sweet potatoes, and a large intake is not recommended (FDA, 2012).
Meat is the most common food source with the bacteria able to withstand temperatures up to 140° F. Prompt refrigeration of leftover cooked meat and reheating to an internal temperature of 170° F is recommended (Bush & Vazquez-Pertejo, 2018b). Fish have been found to have various genotypes of C. perfringens, including type A; these are found predominately on the external surface, indicating environmental contamination and increasing risks to consumers (Sabry, Abd El-Moein, Hamza, & Abdel Kader, 2016). Commercial food preparation is more commonly the source rather than the home. Treatment is supportive, and antibiotics are not given (Bush & Vazquez-Pertejo, 2018b).
Campylobacter is an organism found in both domestic animals and fowl. Sources of infection include contact with infected animals (frequently puppies) or ingestion of contaminated food. Route of infection is both fecal-oral and sexual contact. (Bush & Perez, 2018a). The incidence in the US is estimated at 845,000 per year, with mortality in approximately 76 patients per year. Campylobacter infections are estimated to cause 22,500 DALYs annually. The two most common species are Campylobacter jejuni and Campylobacter coli. People with comorbidities were significantly (14 times) more likely to have a hospital admission based on stool cultures (O’Brien, 2017). Campylobacter fetus poses a specific risk to fetuses and neonates and has a mortality rate of up to 70%. This disorder is associated with contaminated food and beverages, as well as animal contact (FDA, 2012). The peak incidence of Campylobacter occurs during age one to five years. Adults, especially over age 65, are more likely to be affected if predisposing diseases, including diabetes, cirrhosis, or immunodeficiency, are present. Meningitis can occur in infants with C. jejuni (Bush & Perez, 2018a). Campylobacter is more common in males (CDC, 2017a).
Undercooked poultry is the most common source, and chicken livers pose a significant risk from inadequate cooking (O’Brien, 2017). Other food sources include unpasteurized dairy products, vegetables, and seafood. Avoidance of cross-contamination is critical, with particular attention when working with raw poultry products (FDA, 2012).
Campylobacter most frequently results in mild acute enteritis that is self-limiting but can become severe or result in colitis. Watery diarrhea is more common, but bloody diarrhea can occur. Systemic Campylobacter infection has a fever of 100.4 – 104° F, which follows a relapsing or intermittent course. Abdominal pain, commonly in the right lower quadrant, headache, and myalgias, can accompany the fever (Bush & Perez, 2018a). People in industrialized countries experience more severe symptoms than people in developing countries likely due to acquired immunity (Facciola et al., 2017). Patients can also exhibit subacute bacterial endocarditis, reactive arthritis, meningitis, or fever of unknown origin rather than enteric symptoms. Stool samples contain white blood cells (WBC), and rapid molecular stool tests are used for diagnosis. Antibiotics are not used routinely as the infection normally resolves spontaneously. Common antibiotics used when spontaneous resolution does not occur are erythromycin (Erythrocin) and azithromycin (Zithromax). Patients with extraintestinal infections may be prescribed gentamicin (Genoptic), ampicillin (Omnipen), erythromycin (Erythrocin), or a third-generation cephalosporin, such as ceftazidime (Fortaz) to prevent relapses (Bush & Perez, 2018a; CDC, 2017a).
Sequela includes reactive arthritis, Guillain-Barre syndrome (GBS), Miller Fisher syndrome, hemolytic uremic syndrome, inflammatory bowel disease, and functional gastrointestinal disorders. Reactive arthritis onset is approximately two to four weeks after the infection, occurs most often in the knees, and complete resolution occurs in six months. GBS is rare; estimates of occurrence range from 1:1000 and 1:5000, but it is the most significant health consequence (O’Brien, 2017). Previous Campylobacter infection has been found in approximately one-third of GBS cases worldwide (Facciola et al., 2017). Progression is rapid, with the most significant weakness experienced in the first two weeks after the onset of neurologic symptoms. Approximately one-third of patients have muscle weakness for more than three years, and 3% have relapses of weakness for many years. Campylobacter jejuni is most closely related to the onset of GBS due to its mimicry of peripheral nerve proteins. Early diagnosis and treatment of neurologic symptoms is key to positive outcomes. Care for this patient includes plasmapheresis, high-dose immunoglobulin therapy, and supportive care that may include mechanical ventilation. Miller Fisher syndrome is a nonparalytic variation of GBS with ataxia, areflexia, and ophthalmoplegia. Hemolytic uremic syndrome following a Campylobacter infection can lead to a pulmonary-renal syndrome that causes life-threatening pulmonary hemorrhage on rare occasions. Incidence of irritable bowel syndrome (IBS) increases three-fold following a Campylobacter infection. Other gastrointestinal disorders, such as functional dyspepsia and constipation, have been found subsequent to infection (O’Brien, 2017).
Staphylococcus aureus organisms are everywhere and virtually impossible to eliminate from the environment. It is one of the most resistant non-spore-forming human pathogens. It survives a wide range of temperatures (44 – 118° F: optimum 95° F) and pH ranges (4.5 – 9.3, optimum 7.0 – 7.5). It grows with low water activity and is highly tolerant of salts and sugars (FDA, 2012). With these characteristics, it is easy to see that approximately 25% of people have Staphylococcus on their skin. Under specific conditions, like those found in food products, the organism produces a toxin that causes food poisoning. The onset of symptoms after ingestion of the toxin is usually rapid, ranging from 30 minutes to 8 hours (CDC, 2018d). The toxins produced are heat stable and act as pyrogenic toxin superantigens that cause immunosuppression and nonspecific T-cell proliferation (Kadariya, Smith, & Thapaliya, 2014). The single-chain protein of this enterotoxin is resistant to trypsin and pepsin, which usually destroy protein molecules. Each of the known staphylococcal enterotoxins causes emetic activity (FDA, 2012). Severe vomiting begins early in the course with accompanying nausea and abdominal stomach cramps. Diarrhea can also occur (Bush & Perez, 2018g). Significant systemic symptoms from fluid loss can occur and include transient blood pressure and pulse changes along with dehydration, headache, and muscle cramping. Symptoms are intense but usually resolve in a few hours to one day. Death is rare but can occur in infants, the elderly, and the severely ill. Identification of the toxin in food and the emesis or stool of the patient are diagnostic. Enzyme-linked immunosorbent assay-based (ELISA-based) methods are common to identify the enterotoxin (FDA, 2012).
The first outbreak investigation of staphylococcal foodborne disease was in 1884 in Michigan, where the contaminated food was cheese. Since that time, a variety of foods have been identified, along with prevention measures. The most common foods are meat and poultry dishes (55% of S. aureus outbreaks). Handling of foods increases the risk for transmission, and more cases occur in restaurants and delis compare to homes. Adequate time and temperature for cooking, limited time and control of temperature during holding, and food preparation at one time rather than in multiple steps across time, are essential to decrease the risk. It is also necessary to avoid cross-contamination by adequate cleaning and processing of equipment. Handwashing is key to prevention, and while gloves are helpful, frequent changing of gloves and handwashing remains important. The first case of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) occurred in a low-risk person from a food handler who had visited a nursing home and subsequently prepared coleslaw in a restaurant (Kadariya et al., 2014).
Toxoplasmosis is usually asymptomatic in healthy people. The lymphadenopathy and flu-like symptoms are mild. Pregnant people and immunocompromised, especially with HIV/AIDS, are at the highest risk for more severe symptoms (Heavey, 2018). Infection with T. gondii during pregnancy may be asymptomatic or present general symptoms. However, the effects on the fetus are severe. Transplacental transfer to the fetus can result in increased placental thickness, fetal splenomegaly, fetal hepatomegaly, hydrocephalus, fetal ventricular dilation, fetal intracranial calcification, or fetal chorioretinitis. Ultrasound can be used to detect many of these changes (Pfaff & Tillett, 2016). Abortion, stillbirth, or birth defects may occur. Neonates with toxoplasmosis have jaundice, rash, hepatosplenomegaly, and a characteristic tetrad of the following abnormalities: bilateral retinochoroiditis, cerebral calcifications, hydrocephalus or microcephaly, and psychomotor retardation. Children who are born with minimal symptoms may experience intellectual disability, seizure, or retinochoroiditis within months or years later. Serologic testing, PCR-based assays of blood, cerebrospinal fluid, tissue or amniotic fluid, and histopathologic evaluation of biopsies are diagnostic. With neurologic toxoplasmosis, a head CT or MRI with contrast are performed in addition to a lumbar puncture (if no signs of increased intracranial pressure). Treatment of neonates and immunocompromised patients includes pyrimethamine (Daraprim), sulfadiazine (Lantrisul), and leucovorin (Wellcovorin) (Pearson, 2019a). Due to toxic effects on the fetus, the previous drugs are not recommended during pregnancy. Spiramycin (Provamicina) is not available in the US directly, but the FDA can assist in acquisition (Pfaff & Tillett, 2016). The primary prevention is eliminating contact with cat feces, particularly before and during pregnancy. Since soil can pose a risk for contamination, gloves should be worn for gardening. Food is commonly contaminated; strict handwashing by all food handlers, as well as assuring that all meats reach an internal temperature of 170°F, can prevent transmission (Pearson, 2019a). Further research is needed, but recent studies have linked the presence of T. gondii antibodies to neurologic changes that include schizophrenia, suicidal ideation, dementia, addiction, and autism (Heavy, 2018).
Escherichia coli (E. coli) is one of the most numerous organisms of the normal flora within the large intestine. While the most common infection caused by E. coli is when the urinary system becomes contaminated, some strains can cause diarrhea and are frequently foodborne. The five strains that most commonly cause diarrhea include the enterohemorrhagic (EHEC), enterotoxigenic (ETEC), enteroinvasive, enteropathogenic (EPEC), and enteroaggregative (EAEC) (Bush & Perez, 2018c). ETEC most commonly causes Traveler's Diarrhea. Both food and water can be sources with food that is washed in local water or handled improperly, initiating the infection(Boyce, 2019). Symptoms are usually mild and brief, but some patients experience extreme watery stools. Antibiotics are not commonly used but can be effective in reducing the duration and severity. Both ETEC and EPEC are a high risk in children, and EPEC is specifically known to be higher in bottle-fed infants. EPEC had a high general mortality rate in the past (25 – 50%), but improvements in sanitation and medical treatment of fluid loss have decreased this in developed countries. The onset of symptoms is usually within four hours with profuse, watery diarrhea, vomiting, and low-grade fever. Occasionally diarrhea lasts from 21 - 120 days (FDA, 2012).
The EHEC strains are associated with the most severe disease consequences, including STEC. These strains can produce cytotoxins, neurotoxins, and enterotoxins. While there are over 100 serotypes of STEC, the most common in North America is 0157:H7. The toxins produced harm both the mucosal cells and vascular endothelial cells of the large intestine. Diarrhea may begin as watery but within the first 24 hours the diarrhea becomes grossly bloody. The patient also has severe abdominal pain and watery diarrhea, which usually lasts from one to eight days. Fever is typically low-grade, if present, but occasionally can reach 102° F (Bush & Perez, 2018d). Hemolytic-uremic syndrome (HUS) and thrombotic thrombocytopenic purpura develop in approximately 3 - 7% of cases (FDA, 2012). A sudden decrease in hematocrit and platelets, an increase in serum creatinine, hypertension, signs of fluid overload, signs of increased bleeding events, and neurologic changes are indications of HUS. Diagnostic testing of stool cultures requires special media and a specific request for organism serotype identification. Rapid stood assay for Shiga toxin or genetic testing provides more specificity and can be essential for outbreak management. Most of the treatment of EHEC is supportive. Antibiotics are not beneficial, and fluoroquinolones such as ciprofloxacin (Cipro) and levofloxacin (Levaquin) increase the risk for HUS (Bush & Perez, 2018d). One possible explanation has been that the antibiotics break down the bacteria and cause the release of more of the Shiga toxin (FDA, 2012). Cattle are the primary reservoir for STEC, and changes in meat processing have reduced meat contamination. Notification of public health authorities of outbreaks of bloody diarrhea promotes greater outbreak management and prevention. Foods that have significant risks are undercooked beef (especially ground beef), unpasteurized milk, and vegetable crops contaminated by cow manure (Bush & Perez, 2018d). Incidence estimates in the US for foodborne ETEC is 17,000 and other E. coli diarrhea 12,000. US acquired STEC 0157 affects roughly 63,000 people annually, with 3,000 hospitalizations and 20 deaths. STEC non-O157 affects 169,000 people annually, with 405 hospitalizations and an estimated death rate of 0.3% (CDC, 2019e).
Listeriosis is a foodborne disease that affects a small number of people compared to other organisms but is one of the leading causes of death from foodborne disease. While most healthy people experience only mild gastroenteritis, the more severe invasive form results in an overall fatality rate of 15 – 30%. In people with septicemia, the fatality rate is 50%; when meningitis occurs, the fatality rate is approximately 70%. Perinatal/neonatal infections cause the fatality rate to increase to 80%. Onset is rapid for the gastrointestinal form and occurs in a few hours up to three days after food ingestion. The invasive form, which results in septicemia and meningitis, has a variable incubation from three days to three months. The health status of the patient at onset is one of the predictors of disease severity in most people. Healthy individuals are most likely to experience the gastroenteric form and shorter duration, while people who have chronic health problems, immunocompromised, or elderly are more likely to experience the invasive type (FDA, 2012). The most common food source is unpasteurized dairy products, soft cheeses, blue-veined cheese, deli meats, hot dogs, meat salads, unwashed raw vegetables, and refrigerated smoked seafood. Treatment is intravenous ampicillin (Omnipen) for at least 14 days. For those allergic to ampicillin (Omnipen), trimethoprim with sulfamethoxazole (Bactrim) is generally accepted. (Pfaff & Tillett, 2016). Listeria is both salt-tolerant and can grow in temperatures below 34° F. It is found throughout the natural environment in moist environments, soil, and decaying vegetation. One of the cases that illustrate the tenacity of Listeria is a case in 1989 in a meat processing plant. The same strain was found 11 years later in the same meat processing plant. Efforts to decrease disease have led to declines over the last 20 years. Since Listeria contamination can include food workers, incoming air, raw materials, and food processing environments, all food production employees need sufficient education on effective control and prevention measures. In processing areas, the most significant risk occurs after the food is processed with cross-contamination (FDA, 2012).
Listeriosis presents a specific risk during pregnancy. Approximately 14% of cases are in pregnant women, who are at ten times the risk of the general public. Immunologic changes during pregnancy increase the risk, and the highest risk is during the third trimester. The bacteria target placental cell receptors. Transmission during pregnancy can be directly from the mother or can be introduced to neonates as a nosocomial infection due to inadequate handwashing and surface hygiene. While its occurrence is rare, the consequences are extreme. The mother may not be aware of the infection with flu-like symptoms, headache, gastritis, diarrhea, and backache. Some experience severe abdominal pain and fever. A specific concern is that it may be two months after infection before symptoms are experienced. A precaution is that fever of 100.6°F in a pregnant woman with signs and symptoms of Listeria should have blood cultures. Even if the mother experiences mild to moderate symptoms, the fetus is greatly affected by risk for miscarriage, stillbirth, neonatal meningitis, and death. Early-onset symptoms in the neonate include respiratory distress, poor muscle tone, pallor, meconium staining, and a diffuse, grainy rash that can develop into abscesses (granulomatosis infantiesepticum). Late-onset symptoms, with an average time of onset at 14 days after birth, generally involve the central nervous system and include irritability, lethargy, stiff neck, fever, and seizures (Pfaff & Tillett, 2016).
Additional Reportable Foodborne Diseases
There are four genera of Shigella that cause inflammatory dysentery, including A (S. dysenteriae), B (S. flexneri), C (S. boydii), and D (S. sonnei). S. sonnei is most common in the US (Bush & Perez, 2018f). The only host is humans. Shigellosis is the sixth most common domestically acquired foodborne illness in the US, with 31% of the cases foodborne. Contamination of food or water with human feces is the primary source; raw foods, as well as dairy products, poultry, and salads such as tuna, potato, and macaroni, can transmit the disease (FDA, 2012). Food or fomites can spread the disease indirectly, and flies can serve as vectors (Bush & Perez, 2018f). The organism is sensitive and will break down quickly, so it is critical to test the sample as quickly as possible for accuracy. Shigellosis (bacillary dysentery) is the common name for the illness. Diarrhea can be simply watery stool or in severe cases, diarrhea with blood and mucus. Young children, the elderly, and immunocompromised people are affected with greater severity. In unsanitary conditions, the disease spreads rapidly (FDA, 2012). The onset of symptoms occurs 8 - 50 hours after the ingestion of contaminated food. In adults, the patient experiences gripping abdominal pain, urgency to defecate (tenesmus), and passage of formed feces that temporarily relieves the pain. The severity of the diarrhea is progressive, and the stools become liquid with mucus, pus, and sometimes blood. Severe tenesmus may result in rectal prolapse or consequent fecal incontinence. The disease is self-limiting with mild disease resolving in four to eight days, but more severe disease may take three to six weeks to resolve. With some patients, the onset is sudden, with liquid stools, vomiting, and severe dehydration or no symptoms before the onset of delirium, seizures, and coma. The stool may be white liquid without fecal material, often described as rice-water stools. In this form, death may occur in 12 - 24 hours. Children have more severe symptoms and can die in the first 12 days if untreated. Initially, the child has fever, irritability, drowsiness, anorexia, nausea, vomiting, diarrhea, abdominal pain, distention, and tenesmus. Progression in three days changes the stool to containing blood, pus, and mucus and may increase to more than 20 stools per day with resulting weight loss and severe dehydration. Diagnostic testing includes stool cultures, the presence of fecal leukocytes, an elevated WBC count (usually around 13,000), hemoconcentration, and indications of metabolic acidosis. Supportive care with fluid replacement is essential for patients. For the severely ill, antibiotics can be used. This may include a fluoroquinolone (such as ciprofloxacin [Cipro]), azithromycin (Zithromax), or a third-generation cephalosporin (such as ceftriaxone [Rocephin]). It is important not to give antidiarrheal drugs such as loperamide (Imodium), as these may prolong the illness. Meticulous handwashing by the patient and caregivers is crucial. Clothes and bed linen require detergent and hot water for cleaning (Bush & Perez, 2018f).
Vibrio is a bacteria found in saltwater and brackish (mix of salt and fresh) waters. Raw or undercooked seafood, especially oysters, are the primary food source. In the US, the incidence is estimated to be 80,000 cases per year, with 500 hospitalizations and 100 deaths. Transmission occurs most often from May through October. Factors that increase the risk from Vibrio include immunosuppression, liver disease, cancer, diabetes, HIV, thalassemia, bariatric surgery (or other patients with partial gastrectomy), and those on medications to lower stomach acid (CDC, 2019g). Vibrio organisms are susceptible to acidity, freezing, and cooking, and killed by common disinfectants, including bleach and alcohol (FDA, 2012).
The most severe foodborne disease caused by this family of bacteria, cholera, is caused by Vibrio cholerae. Contaminated water and seafood can cause acute small bowel infection. The bacteria produce an enterotoxin that causes the small bowel mucosa to hypersecrete an isotonic electrolyte solution. The patient experiences an abrupt onset of painless, rice-water diarrhea that can exceed one liter per hour but is usually less. Vomiting occurs, but nausea is not typical. Hypovolemia, hypokalemia, and hemoconcentration occur, but serum sodium remains normal. Symptoms of extreme thirst, scant urine, muscle cramps, and weakness occur along with sunken eyes and wrinkling of the skin on the fingers. Renal tubular necrosis, circulatory collapse with cyanosis, and stupor can occur without fluid replacement. Incubation is one to three days. While rare, some people become chronic biliary tract carriers. Culture and serotyping of the stool are used for diagnosis. A rapid dipstick testing for cholera is available for public health purposes, where laboratory testing is limited. Milder cases can be managed with standard rehydration; severe cases require intravenous administration of isotonic fluids as well as potassium replacement to resolve hypokalemia, which is critical in pediatric clients. Once the patient is rehydrated, the fluid administration rate is based on stool volume. Oral rehydration solution (ORS) packets are available in areas where cholera is endemic. The packets contain 13.6 g glucose, 2.6 g sodium chloride, 2.9 g trisodium citrate dihydrate (or 2.5 g potassium bicarbonate), and 1.5 g potassium chloride, added to one liter of clean water. When packets are not available, six small spoons of sugar and one-half spoon of salt can be substituted. The cessation of vomiting and return of appetite are indications that solid food can be resumed (Bush & Perez, 2018b).
Vibrio vulnificus is much less common, with approximately 96 cases per year acquired in the US (CDC, 2019e), but has a mortality rate of 35% in septicemia cases. The onset of V. vulnificus is 12 hours to 21 days, with a mean time to septicemia of four days. The mean duration of septic illness is 1.6 days, reflecting, to some extent, the high mortality rate once septicemia occurs. In healthy people, the acute enteritis is usually mild and self-limiting, but susceptible people are at high risk for septicemia. While other seafood and cross-contamination are risks, 90% of cases in the US are from eating raw gulf coast oysters. Factors that increase the risk are chronic liver disease (including transplantation or liver cancer), medications and diseases causing immunosuppression, insufficient gastric acid, diabetes, renal disease, or intestinal disease. It is critical to teach people at risk to eat cooked seafood and take measures to decrease cross-contamination (FDA, 2012).
The Vibrio species that cause less severe foodborne diseases include V. parahaemolyticus, V. mimicus, and V. hollisae, which are typically associated with inadequately cooked seafood, especially shellfish (Bush & Perez, 2018e). V. parahaemolyticus is not usually transmitted by the fecal-oral route because the organism is damaged by freshwater (FDA, 2012). Symptoms typically include diarrhea that is large in volume and watery, abdominal pain, weakness, and tenesmus. Less frequently, the patient may exhibit nausea, vomiting, low-grade fever, and bloody stools (which can contain granular leukocytes). The culture media used specifically for Vibrio is thiosulfate citrate bile salts sucrose medium, and both the stool and the suspected food can be cultured. Treatment includes replacement of a large amount of fluid and electrolytes lost. Antibiotics are not generally used, but for severe cases, ciprofloxacin (Cipro) or doxycycline (Vibramycin) may be given as a single dose. Oral cholera vaccines, such as Vaxchora, are available and recommended for people who plan to travel to endemic areas (Bush & Perez, 2018e).
Foodborne Clostridium botulinum has a hospitalization rate of approximate 83% and a fatality rate of 17% (CDC, 2019e). Even with treatment, mortality is between 5% and 10%. The bacteria are anaerobic and produce a potent neurotoxin. The neurotoxin blocks motor nerve terminals at the neuromuscular junction, resulting in flaccid paralysis. Improperly home-canned foods are the most common source; it is more common in low acid foods such as corn, peppers, green beans, beets, asparagus, and mushrooms. Other foods at risk are tuna fish, chicken and chicken livers, liver pate, luncheon meats, lobster, and smoked or salted fish. The onset of the disease varies from four hours to eight days but is typically from 18 – 36 hours. Neurologic symptoms begin early with diplopia, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Neurologic progression is symmetrical and downward, starting at the head with eventual paralysis of arms, trunk, legs, and respiratory muscles. When the diaphragm and chest muscles become involved, death from asphyxia can occur without intervention. Early administration of botulinum antitoxin, which is available from the CDC, can improve outcomes. Mechanical ventilation may be necessary for weeks to months. While the symptoms are highly diagnostic, differentiation from other disorders may be difficult. Stool and serum can be tested for the presence of the toxin, but the most specific test is the mouse neutralization test that takes 48 hours (FDA, 2012).
The first sign of infant botulism is constipation. Subsequently, the infant exhibits a flat facial expression, poor feeding with weak sucking, weak cry, decreased movement, difficulty in swallowing, excessive drooling, progressive muscle weakness, and breathing problems. An antitoxin specific to infant botulism (BIG-IV), is available and should be administered early. Supportive treatment is given with the implementation of mechanical ventilation and intensive care for weeks to months. While many items may be risks, the one food specifically linked to incidence is honey. The caution to not give honey to any child under 12 months of age is essential teaching for preventive care. Currently, an adult form of botulism that is similar to infant botulism has been found in patients with a surgical alteration of the gastrointestinal system and/or antibiotic therapy (FDA, 2012).
As a foodborne disease, brucellosis in the U.S is most frequently contracted from the consumption of imported raw milk or soft cheese products made from raw milk from goats or cows. Humans are more likely to contract the species Brucella meletensis, which is from goats. The disease burden is the greatest in endemic countries where goats are raised, and there is no pasteurization. A zoonotic transfer (infectious disease spread from an animal species to human) occurs with raw milk being the most common source but human contact with the reproductive parts of infected animals as another source. Human to human transfer is rare but has occurred through reproduction and breastfeeding. In animals, abortion is a common symptom; in humans, this is rare. Pasteurization of milk (mandated by law since 1947), along with surveillance and control measures, has minimized the risk of this disease from food products in the US. The onset of symptoms is generally within three weeks but can be longer. The disease was once known as undulant fever because of intermittent fever and sweating. Septicemia happens at the beginning of the illness. Without treatment, the disease can become chronic with the recurrence of febrile illness. Development of brucellar spondylitis, a focalization of brucellosis in the bones that is most common in the lumbar vertebrae, can also occur. Diagnostic tests include isolation of the organism from blood or bone marrow, testing for anti-Brucella antibodies, and radiologic examination for vertebral changes and bone spurs. An aggressive combination antibiotic treatment for up to six weeks can prevent relapses in up to 90% of patients. The most common combinations are doxycycline (Vibramycin) plus rifampin (Rifadin) or doxycycline (Vibramycin) plus streptomycin (Streptomycin) (FDA, 2012).
Two types of F. tularensis, type A and B, cause tularemia. Type A is found primarily in rabbits and rodents, is more virulent, and occurs mostly in the US and Canada. Food can be contaminated; however, other routes include bites of arthropod vectors (such as deer flies, ticks, and fleas), inhalation, and direct contact with infected tissues or material (Bush & Perez, 2018h). Animal meat, especially undercooked meat from rabbits and hares as well as milk, can be food sources. The other risk, less specific to the food, is if rodent droppings have contaminated the food. It is considered one of the most infectious microorganisms because inhaling as few as ten bacteria cells can lead to infection with a high mortality rate; in foodborne, over one million are required. The onset of symptoms can be from one day to a week but is typically three to six days. Some of the organisms are more virulent, and this factor influences outcomes. Infected food can cause either oropharyngeal infection, which causes pharyngitis and necrotic cervical adenopathy or gastrointestinal infection, with a range of symptoms from mild diarrhea to severe bowel damage. Diagnosis includes confirmation made by culture on enriched media, but real-time PCR, direct fluorescent antibody (DFA), and ELISA-based techniques are used for preliminary diagnosis (FDA, 2012). Leukocytosis or only an elevation in the proportion of neutrophils, eosinophils, and basophils in the CBC provide evidence of infection. In severe cases, streptomycin (Streptomycin) injectable is used for tularemia (Bush & Perez, 2018h). Foodborne tularemia is rare in the US. It is important to note that any form can spread to the lungs and/or meninges, causing severe disease and increased mortality (FDA, 2012).
Hepatitis A (HAV) has an estimated hospitalization rate of 37.5% and a death rate of 2.4% based on the present CDC data available (CDC, 2019e). With the implementation of the Hepatitis vaccine, there was a 95% decrease in incidence from 1995 - 2011. From 2011 - 2017, the incidence has increased by 140%; people who use intravenous drugs, and the homeless are at the greatest risk (CDC, 2019i). CDC (2019h) identifies other people at risk for HAV: travelers to countries with high or endemic HAV, men who have sex with men, people with clotting factor disorders, people who work with primates, and people with adopted children from countries with high or intermediate endemic HAV. Hepatitis A is a hardy virus that can survive freezing; food must be cooked to a temperature of over 185°F for at least one minute (CDC, 2019h). The virus can live for months in environments with poor sanitation and improper sewage disposal (Walker, 2018).
People with HAV may be asymptomatic, which is most typical in children less than six, or can be a severely disabling disease (FDA, 2012). Incubation is typically 28 days but can range from 15 - 50 days. In adults, the onset is usually abrupt with abdominal pain, fever, malaise, anorexia, nausea with or without vomiting, and diarrhea. Progression of the disease is noted by liver symptoms that include jaundice, dark urine, clay-colored stool, and hepatomegaly. Diagnosis consists of a blood test for serum immunoglobulin M (IgM) anti-HAV antibodies that are detectable five to ten days after exposure. Reverse transcriptase-polymerase chain reaction (RT-PCR) may also be used to detect HAV ribonucleic acid (RNA) (Walker, 2018). Fulminate hepatitis can occur with liver failure and is most likely in patients with chronic liver disease. Mortality in these cases is 70 – 80% (FDA, 2012). During the course of disease, liver status can be established by tests for serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and bilirubin. Physical care during the disease includes adequate rest, a diet of small meals that are high-calorie and high-protein (based on liver status), and modification of medications that are metabolized by the liver as directed by the health care provider. Environmental care includes routine handwashing with soap and water for 15- 20 seconds, no sharing of eating utensils or toothbrushes with family, wearing gloves, and disinfection of bed linens, bathroom surfaces, and laundry used by the patient (Walker, 2018). After recovery, serum IgG antibodies are present, and immunity is life-long (CDC, 2019h).
Vaccination has made HAV a preventable disease. Children from 12 months to 18 years should receive two doses of Havrix or Vaqta with the second dose 6 –18 months after the initial dose. These vaccines can also be given to adults who have been exposed to HAV. For general prevention in adults, three doses of the Twinrix vaccine that includes both hepatitis A and hepatitis B are given; the second dose one month after the initial dose and the third dose six months later. If a person has travel planned with risk for exposure, four doses of Twinrix can be given with three doses in 21 days (initial, day 7, and day 21-30) and the fourth dose at 12 months after the initial dose. Hepatitis A vaccine can be given during pregnancy. Neither health-care workers nor food service workers need routine vaccination against HAV. Immune globulin can be administered to people who have been exposed to HAV but need to be administered within two weeks of exposure (CDC, 2019h).
Estimates of incidence, based on serologic surveys, indicate that 80% of the US population has had cryptosporidiosis. The organism, an oocyte, is half the size of a red blood cell and requires as few as 10 to cause an infection. Ingested food and water are likely sources. Still, pool water is a major vehicle as the organism is extremely tolerant of chlorine and can exist for long periods in the presence of bleach. Infection from person-to-person by fecal-oral route is common. Fresh produce is the most common food source, but juices and milk may also be infected (FDA, 2012). Once in the body, Cryptosporidium differentiates into two forms; thick-walled organisms are shed in the stool, and thin-walled organisms break down in the intestinal wall and can cause symptoms. The onset of symptoms is typically one week, and 80% of those infected have symptoms. In immunocompetent people, the onset is usually sudden with profuse, watery diarrhea, and abdominal cramping. Occasionally, the person may have nausea, anorexia, fever, and malaise. The symptoms typically resolve in one to two weeks but may last for a month. Caution should be advised because the organism continues to be shed in stools for several weeks after symptoms have resolved. Symptom onset in immunocompromised patients is much more gradual, but the diarrhea is more severe, with fluid losses of more than 5 -10 liters per day in AIDS patients. Diarrhea can become intractable and may persist for life in these patients (Pearson, 2018a). A CD4 count of fewer than 180 cells/mm3 is the trigger point for the greatest risk for severe and protracted disease in AIDS patients (FDA, 2012). Diagnostic testing includes microscopic stool examination of multiple samples using phase-contrast microscopy, staining with modified Ziehl-Neelsen or Kinyoun techniques, as well as immunofluorescence microscopy with fluorescein-labeled monoclonal antibodies. Specific enzyme immunoassay for fecal Cryptosporidium provides greater sensitivity than microscopic examination alone. Intestinal biopsies may reveal Cryptosporidium in digestive epithelial cells (Pearson, 2018a).
Cyclospora cayetanensis is a protozoan parasite that is shed in the feces of vertebrates but requires one to two weeks outside of the body in the environment to mature and become infective. The disease is more common in tropical and semi-tropical climates, especially during the rainy season (FDA, 2012). Outbreaks in the US have been associated with contaminated fresh vegetables, including prewashed salad mixes, basil, snow peas, and cilantro (Pearson, 2018b). Symptom onset occurs seven to ten days after ingestion. The diarrhea is watery, can be explosive, and is accompanied by abdominal pain and bloating. While some patients are asymptomatic, others have severe, flu-like symptoms with headache, vomiting, fever, and general aching (FDA, 2012). AIDS patients are at risk for developing severe, intractable, voluminous diarrhea, as well as extraintestinal disease that includes cholecystitis and disseminated infection. Diagnosis includes identification of the organism in stool using Ziehl-Neelsen or Kinyoun acid-fast staining technique, and a unique quality of the organism is auto-fluorescence. More than three stool specimens may be necessary because cyst secretion is intermittent. Biopsy of intestinal tissue can reveal intracellular parasite stages. Treatment of the organism is with trimethoprim/sulfamethoxazole (Bactrim), and AIDS patients require higher doses and a longer duration of treatment (Pearson, 2018b). Death is extremely rare, but without treatment, symptoms can last for months, and relapses are possible (FDA, 2012).
Trichinosis is a parasitic infection in which at least a male and female parasite are ingested when infected meat is eaten. Then they spend a day or two in the epithelium of the small intestine. Within three days, the newborn larvae they produced are shed into the intestine. From there, the larvae travel throughout the body and migrate to the liver, lung, eye, heart, and brain but can only survive long-term in skeletal muscle. Once in skeletal muscle, the larvae settle down to live until the animal dies or something eats the animal. Any animal that eats meat can be at risk, but the most common food source for humans has been pork. In the US, changes in pork production have contributed to the decreased incidence of trichinosis; this includes a requirement to cook any meat product fed to pigs (who are omnivores), prevention of rodent contamination in pig enclosures, and required surveillance for Trichinella. Even with these measures, the caution remains that raw pork should always be cooked thoroughly (internal temperature greater than 160°F). Commercial freezing to a lower temperature can also destroy the larvae, but home freezing is insufficient and should never be considered effective for eliminating Trichinella from wild game. Cases in the US have included walrus, bear meat, and cougar, along with more common game meats (FDA, 2012). Symptoms of nausea, abdominal cramping, and diarrhea begin when the newborn larvae begin to increase in number in the digestive system. As the larvae migrate, systemic symptoms including periorbital edema, myalgia, persistent fever (greater than 102°F), headache, petechiae, and subconjunctival hemorrhages begin to present. Eye pain and photophobia frequently occur before chronic myalgia. An increase in eosinophil count begins when the larvae invade tissues, peaks two to four weeks after infections, and decreases once the larvae become encysted in the muscle cells. The larvae that do not go to muscle tissue eventually die, but large numbers present and dying in tissue can result in cardiac, neurologic, or pulmonary complications with death possible. Enzyme immunoassay is the fastest test to confirm the diagnosis. Laboratory measurement of increased creatine kinase and lactic dehydrogenase is found in half the patients. Muscle biopsy is usually not necessary but can be performed for species identification. Early treatment with an anthelmintic, such as albendazole (Albenza) or mebendazole (Vermox), can eliminate adult worms. Once the larvae are in muscle tissue, the medication may not kill the larvae, and larger doses have adverse effects. Analgesics to relieve muscle pain may be given. Some patients experience an allergic response to the larvae; when myocardium or the central nervous systems are involved, prednisone (Deltasone) may be given (Pearson, 2019b).
Common Foodborne Diseases That Do Not Require Reporting
Yersinia hospitalization rate is 34%, and the death rate is estimated at 2% (CDC, 2019e). The two most common species of Yersinia that cause gastroenteritis are Y. enterocolitica and Y. pseudotuberculosis. It is transmitted by the fecal-oral route, and the organism is found in animals (pigs, birds, beavers, cats, and dogs) and insects (fleas, flies, and frogs). Refrigeration does not kill the organism. Foods most at risk to carry Yersinia are meats, especially pork, seafood, and unpasteurized milk. The spread of the organism can occur when handling meat products, during storage, or with poor sanitation and improper sterilization. In the home, handwashing and exclusive use of a cutting board for meat with a separate board for other products can decrease risk (FDA, 2012). Foods, such as chitlins that are prepared at home and include pork intestines are a known risk. Physical contact should not occur with young children by any person while preparing this food (CDC, 2019j). In adult patients, the disease is most commonly self-limiting diarrhea. Children less than five years old exhibit fever and abdominal pain as well as diarrhea and/or vomiting. Some children complain of headache and sore throat at disease onset, and some may experience bloody stools. The abdominal pain is frequently in the right lower quadrant, and differentiation from appendicitis can be challenging, but yersiniosis has a much higher rate of diarrhea. Unnecessary appendectomies have been performed without adequate diagnostic consideration of yersiniosis. Specimens of feces, blood, or vomit can be tested for the presence of Yersinia in patients with symptoms that indicate possible infection (CDC, 2016). Serology for biotype and PCR methods of molecular-based assays can be used to confirm the diagnoses. Treatment for the gastroenteritis is supportive. Complications are more likely in people with the human immunologic leukocyte antigen, HLA-B27. These include reactive arthritis, glomerulonephritis, endocarditis, erythema nodosum, uveitis, and thyroid disorders. Reactive arthritis can occur in patients who were asymptomatic. Bacteremia is a rare complication. Antibiotics such as gentamicin (Garamycin) or cefotaxime (Claforan) may be given for septicemia or other complications (FDA, 2012).
Foodborne Bacillus cereus is estimated by the CDC (2019e) to affect approximately 63,000 people annually in the US. It has two types based on the predominant symptom: diarrheal or emetic. The diarrheal form has an incubation of 6 – 15 hours, followed by watery diarrhea, abdominal cramps, and occasionally nausea. The emetic form has an incubation of 30 minutes to 6 hours, followed by nausea and vomiting. Both forms are usually self-limited and resolve in 24 hours (Foodsafety.gov, 2019). A cytotoxin was found in a strain of B. cereus that caused a severe outbreak and three deaths. Local and systemic infection of B. cereus has caused pyogenic infections, gangrene, sepsis, meningitis, cellulitis, panophthalmitis, lung abscesses, infant death, and endocarditis. Outbreaks have been attributed to a variety of foods, including rice, beef, turkey, beans, and vegetables; food mixtures such as sauces, casseroles, and soups have also been implicated. Diagnosis is based on isolation of the organism from food, feces, or vomit of the patient. The emetic enterotoxin of B. cereus has been implicated in the development of liver failure in otherwise healthy individuals (FDA, 2018c).
Astrovirus, rotavirus, sapovirus (SaV) and Hepatitis E are viral gastrointestinal illnesses that do not require reporting to the CDC or state agencies (CDC, 2019e). They are all transmitted by the fecal-oral route, and most are spread person to person with food handlers at the greatest risk for spreading. Fecal contamination of water where food is obtained is also a source. In 2012/2014, the largest outbreak in Europe occurred with 1,500 patients in 13 European countries with the source identified as frozen berries. Foodborne transmission of the Hepatitis E virus is increasing with processed pork, wild game, and shellfish as the major sources. SaV is similar to NoV; it is found in shellfish, but rarely transmitted through food. SaV does not bind to HGBAs, nor is there the pattern of susceptibility that occurs with NoV. Rotavirus and astrovirus are also rarely found to be foodborne but are transmitted person-to-person. Some of the emerging viruses with potential for foodborne transmission include SARS coronavirus, H1N1 influenza, and Zika virus. While food consumption is a risk, people who handle food also risk cutaneous transmission. While fecal matter is the main source, an awareness that viruses can also be spread through urine, saliva, and breast milk is necessary (Iturriz-Gomara & O’Brien, 2016).
Prior to vaccination, rotavirus was the most common viral foodborne infection in young children. In the 95 countries where vaccination has been implemented, a 49–89 % decrease in hospital admission for rotavirus and an overall 17–55% decrease in all hospital admissions for gastroenteritis in children under age five occurred within two years of the immunization being initiated. Without immunization, children are at greatest risk from ages 4 – 23 months. Food contaminated with feces of an infected person has been the transmitting agent. Diarrhea and vomiting are typical, and without rehydration, can progress to hypovolemic shock, coma, and death. Unlike NoV, rotavirus immunity progresses with each subsequent infection. The rotavirus vaccine decreases incidence by limiting both infections and shedding of the organism. Diagnosis of even subclinical cases is possible with detection of viral nucleic acid. In developed countries, it is more common in the winter, but there is no seasonality in undeveloped countries. Lack of adequate rehydration therapies results in severe illness, and 90% of the 200,000 deaths worldwide are in developing countries. Treatment with antimotility drugs is not recommended. Probiotics with Lactobacillus rhamnosus strain GG, Lactobacillus reuteri, and Saccharomyces boulardi can decrease the duration of diarrhea. Continuation of breastfeeding or resumption of feeding after rehydration is recommended in children less than six months of age. Zinc supplementation is an added recommendation in developing countries (Banyai, Estes, Martella & Parashar, 2018). Both of the rotavirus vaccines for use in infants are oral drops. RotaTeq (RV5) is given in three doses at two months, four months, and six months of age. Rotarix (RV1) is given in two doses at two months and four months of age. The vaccine should not be given after eight months of age, even if dosing is incomplete. Contraindications include allergic response to the vaccine, immunodeficiency, or a history of intussusception. A vaccine dose should be postponed when the child has moderate or severe illness, including diarrhea or vomiting. Side effects of the vaccine include irritability, mild diarrhea or vomiting. Adverse effects include a risk for intussusception, which usually occurs within a week after the first or second dose (Savoy, 2019).
Non-infectious Foodborne Disease
Food is a daily requirement of all human beings. The two following examples are a reminder that risks can be present beyond infectious disease.
Most nurses are aware of the risk of mercury poisoning from fish during pregnancy. While exposure to mercury should be minimized for everyone, it is most critical during pregnancy because it is linked to the brain development of the fetus. Microorganisms in the water process inorganic and elemental mercury and deposit an organic compound, methylmercury, in the tissue of fish (CDC, 2017b). Fish that eat other fish and have a longer lifespan build up more mercury and are the greatest risk. Fish in this category include orange roughy, king mackerel, marlin, shark, swordfish, tilefish, and bigeye tuna. These should be avoided, especially during pregnancy (FDA, 2019). During fetal development, exposure to methylmercury is known to result in abnormalities and cerebral palsy. Chronic exposure in other ages results in neurologic damage (CDC, 2017b). Current recommendations for nutrition during pregnancy include 8 – 12 ounces of low-mercury fish per week. Some of the low-mercury seafood are catfish, cod, flounder, salmon, sardines, shrimp, light tuna, tilapia, and trout (FDA, 2017).
Rice is a major food in a large part of the world. Inorganic arsenic is found in rice, even in countries like the US, where water has a low arsenic content. Inorganic arsenic is carcinogenic to the bladder, lungs, skin, and prostate (Sohn, 2014). Research by Signes-Pastor, Zens, Seigne, Schned & Karagas (2019) regarding the risk for bladder cancer, supports an elevated risk of arsenic poisoning with the intake of brown rice. Arsenic also increases the risk of heart disease. Immediate symptoms of arsenic poisoning are muscle cramping, gastrointestinal problems, and lesions on the hands and feet. Current experimentation to decrease this risk focuses on identifying and growing rice varieties that absorb less arsenic from the soil and water. The recommendation for safe intake is no more than two or three servings of rice each week. Traditionally, rice has been cooked with equal parts water and rice; cooking rice with three times as much water than rice and rinsing the rice before and after cooking can decrease the arsenic content by 30% (Sohn, 2014).
Scombroid syndrome occurs when fish are contaminated by histamines. Approximately 5% of food poisoning in the US is from scombroid syndrome. Bacteria in fish gills and the gastrointestinal tract are the source of the histamine. Scombridae and Scomberesocidae families of fish are the usual source; this group includes tuna, mackerel, albacore, sardines, anchovies, and mahi-mahi. Neither food processing nor cooking eliminate the histamine from the fish. Onset of symptoms is approximately 10 – 30 minutes after ingestion and it usually resolves in 24 hours. It is self-limiting but can last several days. Flushing sometimes accompanied by hives and edema cause confusion with fish allergy. Scombroid syndrome symptoms also include abdominal pain, diarrhea, nausea, vomiting, headache, dizziness, and palpitations. Some people experience a taste sensation of metallic, pepper, or bitterness, and rarely, wheezing and hypotension occur. Diagnosis includes history as well as histamine testing of the patient’s plasma and from the fish. Patients on isoniazid and monoamine oxidase inhibitors are at increased risk for scombroid syndrome. Administration of rapid-acting antihistamines targets the cause and symptomatic treatment, including intravenous fluids and ranitidine (Zantac) for gastrointestinal irritation and nausea, can be used (Ridolo, Martignago, Senna & Ricci, 2016).
Foodborne Disease Control Measures in the Home
The home is both a setting for food preparation and a shared environment for people with various risks and exposures. While this is evident globally, food safety and handling in the US have experienced recent cultural changes that have increased risk. The FDA (2018a) compiles current data and research of the trends affecting foodborne disease in the US. Lando, Bazaco & Chen (2018) researched the utilization of cell phones during food preparation. Mobile devices have become an extension of self and there was decreased likelihood of handwashing before and after touching the device which increases the risk for contamination with foodborne organisms. The aging of the population and the increase in people who are immunocompromised living at home has increased the risk of foodborne disease. (FDA, 2019). Two groups have been found to have the best foodhandling practices at home, those born before 1940 when foodborne disease was more prevalent and the group that were young adults during the E. coli OH157:H7 outbreak in the early 1990s (Teisl, Lando, Levy, & Noblet, 2015). The availability of products such as donor breast milk necessitates education to assure that risks for disease transmission are minimized by pasteurization and screening of donors as well as correct handling in the home (Moreno, 2016). The challenge of changing older habits to improve food safety is exemplified by current public health education to avoid eating anything containing raw flour, such as dough; raw flour may be contaminated with organisms and has not been treated to inhibit potential for disease (CDC, 2019c).
The CDC and FDA each provide information on food safety for home use. Figure 2 and Figure 3 (below) are examples of teaching tools available to assist people in gaining information to decrease the risk of foodborne illness by implementing safer food handling practices.
Figure 2. Food Safe Shopping & Storage
Figure 3. Food Safe Meal Prep
Evans and Redmond (2018) researched the knowledge and food-handling practices for oncology patients at home. Patients with cancer are more at risk for severe consequences of foodborne organisms with 15-25% of serious Salmonella infections occurring in this population. Recommendations that are good practice with the general population but essential for oncology patients include strict adherence to use-by dates on ready-to-eat food, eating ready-to-eat food within two days of opening, assuring temperatures of refrigerators are at 41°F or less (using a thermometer for accuracy), and completely avoiding raw or undercooked foods especially seafood, eggs, meat, soft cheeses, and unpasteurized dairy products. A thermometer is also necessary to ensure that meat and other food reach the necessary internal temperature of 145-165°F. Reviews of handwashing need to include the use of hot water and soap; rubbing all hand surfaces including the palms, back of hand, and fingers; and drying hands only on paper towels. Household cleaning practices and areas of highest risk should be reviewed. Family members and patients should be taught food safety practices to implement prior to and during the patient’s chemotherapy treatment (Evans & Redmond, 2018).
One of the new areas of concern for the introduction of foodborne illness in the home is the use of probiotics and prebiotics. These products are considered food or dietary supplements in the US and are granted generally recognized as safe (GRAS) status. Products with this status within the FDA are not subjected to close monitoring. Lack of standardization of number and type of cultures used as well as lack of quality control increase potential effects, especially in pediatric patients where use is increasing. Specific risks have been identified related to contamination with a case study in the death of a premature infant from a fatal gastrointestinal mucormycosis related to a contaminated commercial dietary supplement. Other general risks include systemic infections, production of toxins by the probiotic organisms, gene transfer of antibiotic resistance, and unpredicted changes in the immune system. Recommendations to improve quality control for all probiotics and the establishment of standards for probiotic preparation for clinical indications are proposed to decrease the risk (Kolacek et al., 2017).
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