Foodborne illness and disease

• ALSO KNOWN AS: Enteric diseases, food poisoning

DEFINITION: Foodborne illnesses and diseases, or enteric diseases, are transmitted to humans from infectious organisms in food and water, generally resulting in gastrointestinal symptoms that vary in severity and duration. Enteric diseases may be caused by viruses, bacteria, or parasites. Technically, the phrase “food poisoning” refers to ingestion of food-borne toxins rather than infectious agents such as bacteria and viruses.

Enteric diseases are thought to cause about 70 percent of cases of diarrhea. Often, what is referred to as a stomach bug or a twenty-four-hour flu is actually the result of a foodborne illness. It is usually difficult to pinpoint the cause of stomach upset because of the long incubation periods for most infectious agents and because exposure occurs several times each day. As a result, epidemiologists believe that for every known case of food-borne illness, dozens more go unreported. The World Health Organization (WHO) estimated in 2024 that nearly one in ten people becomes ill after eating contaminated food.

To be confirmed as a case of enteric disease, the illness must lead a person to seek medical care. A stool specimen must be collected and sent to a laboratory, which tests the sample for multiple organisms. If the lab confirms a specific pathogen, it must report the case to the local health department, to the Centers for Disease Control and Prevention (CDC), or both. An outbreak is said to occur when two or more cases can be traced to the same source, as when multiple people become ill after eating the same food at a picnic.

Characteristics

Symptoms associated with enteric diseases vary according to the pathogen responsible, but often include diarrhea, nausea, abdominal pain, vomiting, and fever. Generally, food-borne illness results in a temporary, uncomfortable period of stomach upset. A health care provider should be consulted, however, if the patient has trouble keeping liquids down or has diarrhea that persists for more than three days and is accompanied by a fever of more than 101.5° Fahrenheit, is bloody, and leads to dehydration. In addition, an estimated 15 percent of people who experience acute gastroenteritis develop reactive arthritis within four weeks of infection with Campylobacter, Salmonella, Shigella, Yersinia, or, occasionally, Escherichia coli O157:H7. Symptoms of this type of arthritis include lower extremity stiffness and pain.

The most common cause of foodborne illness in the United States is the family of noroviruses (Norwalk virus being the best known). The incubation period is twelve to forty-eight hours, and the illness lasts for twelve to sixty hours. Symptoms include nausea, vomiting, abdominal cramping, diarrhea, fever, muscle pain, and headache. Common sources include shellfish and other foods (such as those in salad bars) contaminated by infected persons.

Campylobacter infections result in the onset of symptoms two to five days after the consumption of contaminated raw or undercooked poultry, unpasteurized milk, or contaminated water. Symptoms, including diarrhea (sometimes bloody), cramps, fever, and vomiting, last two to ten days.

Salmonella spp. are commonly found in eggs, poultry, unpasteurized milk and juice, cheese, raw fruits and vegetables (such as sprouts and melons), and street-vended foods. Most strains of Salmonella cause symptoms that include diarrhea, fever, cramps, and vomiting. Certain strains result in typhoid fever, with fever, headache, constipation, malaise, chills, and myalgia. Symptoms appear after an incubation period of one to three days and typically last four to seven days. Salmonella typically causes the most hospitalizations of any food-borne illness.

Clostridium perfringens infections have an incubation period of eight to sixteen hours after ingestion of a contaminated food, such as meat, poultry, or gravy; and after ingestion of dried or precooked foods or foods left out of a refrigerator or freezer (at room temperature or higher) for too long. Symptoms include watery diarrhea, nausea, and cramping, which last twenty-four to forty-eight hours.

Giardia is a parasite that causes symptoms one to two weeks after consumption of contaminated water, uncooked food, or food handled by an ill person after cooking. Diarrhea, stomach cramps, and gas can last days or weeks.

Staphylococcus aureus infections commonly result in the sudden onset of severe nausea and vomiting and cramps (and sometimes diarrhea and fever), one to six hours after eating contaminated foods, such as unrefrigerated or improperly stored meats, mayonnaise-based salads, pastries containing cream or cheese, and other prepared foods. Symptoms last twenty-four to forty-eight hours.

E. coli has several forms, most of which are harmless and all of which are common in the digestive tracts of warm-blooded animals (including humans). Enterotoxigenic E. coli (ETEC) is a common cause of travelers’ diarrhea (also known colloquially as Montezuma’s revenge, Delhi belly, and yalla yalla). ETEC infection typically has a one-to-three-day incubation period, after which the infected person experiences watery diarrhea, cramps, and vomiting for three days to one week or more. ETEC is associated with fecal-contaminated water or food.

Less common, but more serious, forms of E. coli are known as enterohemorrhagic E. coli (EHEC), which include E. coli O157:H7 and other Shiga toxin-producing E. coli (STEC). These forms of E. coli result in severe and often bloody diarrhea, abdominal pain, and vomiting, and are more common in children under four years old. Illness manifests one to eight days after the consumption of undercooked beef, especially hamburger, unpasteurized milk and juice, raw fruits and vegetables, and contaminated water. EHEC-associated symptoms generally last five to ten days. In the US, between 2 and 7 percent of individuals infected with E. coli O157:H7 (mostly children and the elderly) develop hemolytic-uremic syndrome annually, and of those, about one-third develop chronic kidney disease, and 3 to 5 percent die. E. coli transmitted from infected poultry and pork products is thought to be a significant cause of around 90 percent of the millions of urinary tract infections (UTIs) that occur each year.

Toxoplasma gondii is a parasite that infects humans through the ingestion of unwashed fruits and vegetables contaminated by animal feces or the ingestion of raw and partially cooked meat (especially pork, lamb, and venison). The incubation period is five to twenty-three days, and symptoms, which are present only in about 20 percent of infected persons, include flu-like illness or swollen lymph nodes (or both), which can last months.

Shigella infections result in symptoms of abdominal cramps, fever, and diarrhea about twenty-four to forty-eight hours after contact with contaminated food and last four to seven days. Shigella is associated with fecal-oral transmission, often spread from an infected food worker to ready-to-eat foods such as raw vegetables, salads, and sandwiches.

Yersinia infections cause symptoms that include diarrhea, vomiting, fever, abdominal pain, and, sometimes, a red rash. Yersinia is associated with undercooked pork, unpasteurized milk, tofu (soy), and contaminated water. Symptoms appear twenty-four to forty-eight hours after infection and last one to three weeks. Rarely, Yersinia can result in a bloodstream infection.

In addition to the foregoing common causes of foodborne illnesses, certain others are tracked by the CDC, often because they can be deadly. Listeria is one such pathogen. Although only three cases occurred for every 100,000 people in the early 2020s, its fatality rate of 20 percent placed it third in the US for food-borne illness deaths, and virtually every infected individual required hospitalization. Listeria can survive refrigeration for weeks, but cooking kills the bacteria. Raw milk, undercooked or raw foods such as smoked salmon, and soft cheeses are the most common food sources. According to the CDC in 2024, Listeria was responsible for 1,250 illnesses and 172 deaths in the US each year, making it the third leading cause of death from foodborne illness.

Treatment

Initial treatment for persons with foodborne illnesses generally focuses on rehydration, because both vomiting and diarrhea tend to lead to potentially dangerous dehydration. Antibiotic therapy is necessary only in cases of invasive bacterial infections, such as Shigella. In persons with mild to moderate Salmonella infection, antibiotic therapy may not be helpful and may actually be harmful; it can lead to the person being a long-term asymptomatic carrier who can easily spread the bacteria to others. Antibiotics should never be used for persons with suspected STEC infection because of the increased risk for development of hemolytic-uremic syndrome, which is fatal in developed countries 2 to 4 percent of the time, and leads to chronic kidney disease in another 5 percent. Similarly, antibiotic therapy in persons with C. difficile infection increases the risk of developing toxic megacolon, with a high mortality rate, which varies based on other medical factors. Antibiotic treatment is ineffective in cases caused by viruses.

Risk Factors

The risk factors associated with foodborne illnesses range from those at the kitchen level to those in the food system as a whole. Raw and undercooked foods, inadequate home canning, cross-contamination (in which bacteria are transmitted by the use of unwashed cutting boards, for example), insufficient hygiene by food service workers, and foods kept at the wrong temperatures are all examples of risk factors at the consumer level.

At the producer level, food system issues include widespread consolidation, industrialization, and globalization, all risk factors for the spread of foodborne illnesses because they can lead to a lack of oversight and inspection and to problems with tracing foods that are produced on an industrial scale. For example, one infected cow can contaminate large amounts of ground beef because meat from many animals is often mixed during the processing of the ground beef.

Labor and economic development issues can play a role in the spread of foodborne diseases. For example, a large percentage of fresh fruits and vegetables comes from countries without chlorinated water supplies. Contaminated water that is used to irrigate fields or wash produce after harvest can lead to Salmonella and E. coli infections inside the tissue of the produce itself, where it cannot be washed off. Farm workers, food service workers, and meat workers without appropriate access to toilets or facilities for handwashing can contaminate food, too.

Industrial-scale, concentrated, or confined animal-feeding operations (CAFOs) are sources of nearly all the meat, poultry, and eggs in the United States. CAFOs generate enormous amounts of animal waste, which is often disposed of by being spread (as raw manure) on agricultural fields. Runoff from these fields can contaminate drinking water. CAFOs are also blamed for increasing the development of antibiotic-resistant bacteria through the routine use of low doses of antibiotics in herds, which causes the animals to grow faster. The close contact of thousands of confined animals also facilitates the spread of pathogens among those animals.

Prevention and Outcomes

In home kitchens, consumers can reduce their risk of food-borne illnesses by practicing four principles of safe food handling: clean, separate, cook, and chill. “Clean” means washing hands and food-preparation surfaces thoroughly and often. “Separate” means keeping items that are used for animal products separate from items used for other foods, and keeping animal products separate from other items in one’s grocery cart, grocery bags, and refrigerator. “Cook” refers to cooking foods to a high enough internal temperature to kill pathogens and staying away from raw or partially cooked foods, such as rare steaks or sauces containing raw eggs. “Chill” refers to refrigerating leftover food promptly in a refrigerator kept at 40° Fahrenheit or lower. Consumers should also practice the so-called 2-2-4 rule for safe handling of leftovers: no more than two hours should pass between cooking the food and refrigerating leftovers; store food in shallow containers (no more than two inches deep) so it cools quickly once refrigerated; and use or freeze the food within four days.

Consumers can also reduce their foodborne disease risk through their food choices. Avoiding or minimizing consumption of animal products is one way to minimize risk, as meat, poultry, seafood, eggs, and dairy are the primary sources of foodborne diseases in the United States. Free-range eggs are less likely to carry Salmonella than eggs from hens kept in battery cages, and organic eggs are even safer than free-range eggs. Meat and poultry from animals raised on smaller farms or pasture, and (for cattle) fed grass rather than corn, are less likely than factory-farmed meat and poultry to carry E. coli and other pathogens.

Only one-quarter of foodborne illnesses originate from improper home food handling, with the remainder caused by problems at the source or somewhere along the chain before food reaches the eater. Regulatory oversight of food in the United States is fragmented among multiple departments and agencies. The US Department of Agriculture (USDA) inspects meat, poultry, and pasteurized and processed eggs, whereas the US Food and Drug Administration (FDA) regulates all other foods. Regulatory fragmentation and resource and budget constraints on inspection processes may be further systemic causes of the ongoing problems related to food safety in the United States.

Impact

The CDC estimated in 2025 that 48 million people get sick from foodborne illnesses annually. Of these, 128,000 people are hospitalized, and 3,000 die. By 2022, the CDC had reported 250 different foodborne diseases.

Foodborne illnesses cost the US economy billions of dollars each year. Costs are incurred by patients and the health care system for treatment. Patients may lose wages, and their illnesses are a drain on productivity. In 2023, about 47.8 million cases of foodborne illness in the US cost $74.7 billion.

Outbreaks also lead to food recalls and associated costs. Between 2007 and 2015, several notable outbreaks occurred. Westland/Hallmark recalled more than 143 million pounds of beef deemed unfit for consumption, and the Peanut Corporation of America recalled more than 3,900 different bulk peanut butter products from roughly 360 different companies because of suspected Salmonella contamination. The CDC reported 250 multistate outbreaks between 2017 and 2020, which were linked to 7,659 illnesses, 2,044 hospitalizations, and 41 deaths. These outbreaks increase food costs and cause distrust in the food system.

In late 2015, two outbreaks of food-borne illness severely damaged the reputation of the popular nationwide restaurant Chipotle. After the CDC linked more than fifty cases of E. coli STEC O26 to food served at several of the chain's restaurants in nine states throughout the country, questions were raised once again about the lack of understanding regarding food-borne illness and food safety, especially because of Chipotle's dedication to using fresh and organic products. The concern was further heightened when a second outbreak occurred at a Chipotle in Boston that left several Boston College students ill with norovirus.

Further unsettling for consumers was the 2022 recall of Abbott Laboratories' infant formula due to concerns of Cronobacter, Salmonella, and other illnesses linked to the company's formula-manufacturing facility in Sturgis, Michigan. This led to a nationwide shortage of the necessity, as the plant produced around 8 million pounds of formula per month and was temporarily shut down. Abbott Laboratories was investigated by the FDA in early 2022 after an employee wrote a thirty-four-page document explaining issues of sanitation in the Michigan facility. In 2023, the Department of Justice opened a criminal investigation into the company. In 2025, workers at the facility reported that it was engaging in unsanitary practices similar to those documented in 2022. That same year, the Trump administration cut 3,500 Food and Drug Administration jobs. While the administration said that food safety inspectors had not been eliminated, the Heritage Foundation's Project 2025, a blueprint for the administration's policies, targeted "excessive regulation" of infant formula for reevaluation.

The USDA Summary of Recall Cases for 2024 reported thirty-four recalls totaling 19,913,171 pounds of goods. Of the thirty-four recalls, twelve involved more than one type of meat or poultry species and resulted in a total of 19,156,012 pounds of recalled goods. Five of the recalls affected 255,616 pounds of chicken, and four recalls affected 213,194 pounds of beef.

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