Foodborne illness in the United States is most frequently associated with familiar names: Salmonella, Escherichia coli, and Listeria monocytogenes. These pathogens dominate public health messaging, outbreak headlines, and consumer awareness campaigns. Yet the landscape of foodborne disease is considerably broader. Several other pathogens cause substantial illness, hospitalization, and long-term complications, yet remain comparatively obscure to the general public. Understanding these lesser-known threats is essential for comprehensive food safety.
The Centers for Disease Control and Prevention (CDC) tracks foodborne illness through multiple surveillance systems. While Campylobacter and Salmonella consistently rank as the top causes of gastrointestinal infections monitored by FoodNet, other pathogens account for a meaningful share of the overall burden. Between 2016 and 2018, FoodNet data showed higher incidences of several pathogens compared with previous periods (CDC, July 2024), highlighting the need for continued awareness by both healthcare professionals and the public.
Clostridium perfringens
Clostridium perfringens ranks among the most common causes of food poisoning in the United States, yet it receives far less public attention than its better-known counterparts. According to government estimates, C. perfringens causes nearly 1 million cases of foodborne illness each year (Foodsafety.gov, April 2026). The bacterium is found throughout the environment, including raw meat and poultry, the intestines of animals and humans, and soil.
The defining characteristic of C. perfringens food poisoning is its association with large-scale food preparation. Outbreaks frequently occur in settings where food is prepared for large groups and kept at unsafe temperatures for extended periods, including hospitals, school cafeterias, prisons, nursing homes, and catered events. The bacterium grows rapidly in the temperature “danger zone” between 40 and 140 degrees Fahrenheit, producing a toxin in the intestine that causes illness.
Symptoms develop within 6 to 24 hours after consuming contaminated food and typically include diarrhea and abdominal cramps. The illness usually begins suddenly and resolves within 24 hours. Fever and vomiting are not characteristic features. Dehydration is the primary concern. Young children and elderly individuals may experience more severe symptoms lasting one to two weeks. Treatment focuses on fluid replacement, as antibiotics are not typically required.
Prevention relies on proper temperature control. Cooked food must be kept at 140 degrees Fahrenheit or hotter, or promptly refrigerated at 40 degrees Fahrenheit or colder. Leftovers should be refrigerated within two hours, or within one hour if ambient temperatures exceed 90 degrees Fahrenheit. Large portions should be divided into smaller containers for faster cooling, and leftovers should be reheated to 165 degrees Fahrenheit before serving.
Campylobacter
Campylobacter jejuni is the most commonly reported bacterial cause of foodborne infection in the United States, yet many consumers remain unaware of its significance. It is estimated that 1.5 million people become ill from Campylobacter infection annually (Floridahealth.gov, April 2026) with only a fraction of cases diagnosed and reported. The bacterium grows best near avian body temperature, and birds can carry it without showing signs of illness, making poultry the primary reservoir for human infection.
Campylobacter infection typically manifests as acute gastroenteritis with diarrhea (often bloody), abdominal pain, fever, and nausea, with an incubation period of two to five days. While most people recover fully, the pathogen is associated with serious post-infectious complications. Between 0.2 and 1.7 per 1,000 Campylobacter illnesses lead to Guillain-Barré syndrome, a potentially paralyzing autoimmune disorder of the peripheral nervous system. Campylobacter is estimated to be responsible for 5 to 41% of all Guillain-Barré syndrome cases (Foodborne Pathogens and Disease, January 2020). Additional complications include reactive arthritis and irritable bowel syndrome.
Children under five years of age have the highest incidence of campylobacteriosis, and individuals with weakened immune systems are at increased risk for severe disease, including bloodstream infection. Transmission occurs primarily through eating raw or undercooked poultry or foods cross-contaminated by raw poultry.
Prevention centers on proper cooking and cross-contamination control. Poultry should be cooked to an internal temperature of 165 degrees Fahrenheit. Raw meat juices must be kept separate from produce and other ready-to-eat foods. Handwashing after handling raw poultry is essential.
Yersinia enterocolitica
Yersinia enterocolitica is a psychrotrophic foodborne pathogen of recent concern, meaning it can grow at refrigeration temperatures. In the United States, it is the most common cause of non-pestis yersiniosis, with an estimated annual incidence of approximately one culture-confirmed case per 100,000 persons. Young children under five years old and older adults aged 65 and above are at highest risk of infection.
The clinical presentation of yersiniosis is distinctive. After an incubation period of typically four to six days (ranging from one to 14 days), patients develop fever, diarrhea (potentially bloody), and abdominal pain. The abdominal pain can result from inflamed lymph nodes in the abdomen, a condition known as mesenteric adenitis, which can be severe enough to mimic appendicitis. This mimicry has led to unnecessary surgeries in some cases.
Y. enterocolitica has been associated with consumption of raw or undercooked pork, pasteurized milk, tofu packed in untreated spring water, and contaminated produce. Swine are the principal reservoir of the pathogen. In rare cases, the infection can lead to sepsis, particularly in individuals with iron overload conditions such as hemochromatosis or those with underlying immunosuppression. Post-infectious immune-mediated syndromes, including reactive arthritis and erythema nodosum (painful soft tissue swellings), have been documented.
Prevention focuses on avoiding raw or undercooked pork, consuming only pasteurized dairy products, and practicing good hand hygiene after contact with animals or their feces.
Vibrio Species
The genus Vibrio encompasses a group of bacteria naturally found in coastal waters, including salt water and brackish water. Several species are pathogenic to humans, with Vibrio parahaemolyticus causing the most infections in the United States, accounting for approximately 40% of reported vibriosis cases, followed by Vibrio alginolyticus at about 20%. Vibriosis is estimated to cause approximately 80,000 illnesses annually in the United States (Louisiana State Board of Medical Examiners, September 2023).
Vibrio parahaemolyticus infection typically causes gastroenteritis with symptoms including watery diarrhea, abdominal cramping, nausea, vomiting, fever, and chills, beginning 12 to 24 hours after ingestion but ranging from 4 to 96 hours. Most people recover within three days without treatment. Infection is primarily associated with consumption of raw or undercooked shellfish, particularly oysters.
Vibrio vulnificus presents a far more severe threat and is often referred to as “flesh-eating bacteria”. While less common, its infections progress rapidly from initial cellulitis or necrotizing fasciitis to septicemia and death within 48 to 72 hours. Between 150 and 200 V. vulnificus infections are reported to CDC annually. The mortality rate among patients presenting with V. vulnificus septicemia is 50%, and survivors often require amputation of the affected limb. Risk factors for severe infection include underlying liver disease, diabetes, and immunosuppression.
Climate change is increasing the geographic range and seasonal window of Vibrio risk. Warming coastal waters, heat waves, and severe storms create ideal conditions for bacterial growth. Hurricane Ian was associated with 74 cases of V. vulnificus wound infections and 17 deaths in 2022; Hurricane Helene caused 82 cases and 19 deaths in 2024. The Florida Department of Health reported 11 cases and 4 deaths from V. vulnificus during the first half of 2025 alone.
Transmission occurs through two primary routes: ingestion of raw or undercooked shellfish, and wound exposure to salt water or brackish water containing Vibrio. Open wounds, including those from recent surgery, piercing, tattoos, and other cuts or scrapes, are entry points for the bacterium.
Prevention involves cooking shellfish thoroughly before eating, avoiding cross-contamination of cooked seafood with raw seafood or its juices, and keeping wounds covered when in contact with coastal waters.
Norovirus
Norovirus is not a bacterium but a virus, and it is the leading cause of foodborne disease outbreaks in the United States, accounting for approximately 50% of all foodborne outbreaks. Each year, norovirus causes an estimated 19 to 21 million illnesses, 109,000 hospitalizations, and 900 deaths in the United States (January 2026). Despite these figures, norovirus is less familiar to many consumers than bacterial pathogens.
The virus spreads through the fecal-oral route, either through direct person-to-person contact or indirectly via contaminated food, water, or surfaces. Aerosols from vomitus can also transmit infection. Outbreaks frequently occur in settings where people live or congregate in close quarters, including cruise ships, dormitories, long-term care facilities, and hotels. Contaminated ready-to-eat cold foods such as salads and sandwiches pose particular risk, as do raw shellfish, especially oysters, which concentrate viral particles from contaminated water.
Symptoms typically begin 12 to 48 hours after exposure and include acute onset of vomiting and non-bloody diarrhea, along with abdominal cramps and nausea. Most people recover fully in one to three days. However, the virus is highly contagious, a very low infectious dose is sufficient to cause illness, and infected individuals shed billions of viral particles.
Prevention is challenging because alcohol-based hand sanitizers are not reliably effective against norovirus. Handwashing with soap and water is essential. Contaminated surfaces must be cleaned and disinfected promptly. Infected individuals should not prepare food or care for others until at least 48 hours after symptoms resolve, as they can continue to shed virus even after feeling well.
Shigella
Shigella is a genus of bacteria that causes shigellosis, an acute enteric infection. CDC estimates about 450,000 cases occur in the United States annually, making it the third most common bacterial enteric disease. However, approximately 242,000 of these infections are antimicrobial-resistant, and antimicrobial-resistant Shigella infections are considered a serious threat (CDC, March 2024).
Four species of Shigella cause human illness. Shigella sonnei and Shigella flexneri are most common in the United States, while Shigella dysenteriae type 1, which is rare in the U.S., can be deadly. Shigella boydii is also uncommon in the United States.
Transmission occurs through the fecal-oral route via contaminated hands, food, water, or surfaces. The infectious dose is remarkably low, as few as 10 to 100 organisms can cause infection, making the bacteria easily transmissible in close-contact settings such as daycares, nursing homes, and group living environments. Symptoms include watery, bloody, or prolonged diarrhea, abdominal pain, fever, and tenesmus (the feeling of needing to pass stool even when bowels are empty).
The emergence of extensively drug-resistant (XDR) Shigella strains is of particular concern. In 2015, zero% of reported Shigella infections were caused by XDR strains; by 2022, approximately 5% were XDR. XDR Shigella bacteria are resistant to all generally recommended antibiotics currently used in the United States, leaving clinicians with limited antimicrobial treatment options. These resistant strains can also spread antimicrobial resistance genes to other enteric bacteria. Populations at increased risk for XDR shigellosis include gay and bisexual men, people experiencing homelessness, international travelers, and people living with HIV.
Prevention focuses on handwashing, safe food handling, avoiding swallowing water from recreational sources, and practicing safe sexual behaviors. Individuals with diarrheal illness should not prepare food for others until they have fully recovered.
Analysis and Next Steps
Several trends underscore the growing importance of these lesser-known pathogens. What is new includes the emergence of extensively drug-resistant Shigella strains, increasing from zero to five% of reported infections between 2015 and 2022, raising the specter of untreatable foodborne illness. Also new is the clear association between climate change and Vibrio risk, with hurricane-related wound infections now documented in dozens of cases annually. The continued high burden of Clostridium perfringens, nearly 1 million cases per year, remains underrecognized by consumers.
This matters because food safety messaging has historically focused on a narrow set of pathogens, leaving gaps in public awareness and prevention. A consumer who knows to cook chicken thoroughly may be unaware that large roasts and stews left at room temperature can harbor dangerous levels of C. perfringens. A seafood lover may not know that Vibrio vulnificus poses a 50% mortality risk when it enters the bloodstream. A parent may not realize that a child with severe abdominal pain could have yersiniosis mimicking appendicitis rather than a surgical emergency. The populations most affected include young children, older adults, pregnant women, immunocompromised individuals, and those with underlying liver disease, who face the highest risks of severe outcomes.
What to do now requires expanding food safety education beyond the usual suspects. For consumers, the principles remain the same but must be applied consistently: cook food to safe internal temperatures, keep hot food hot and cold food cold, refrigerate leftovers promptly, and avoid cross-contamination. For raw shellfish, at-risk individuals should consider avoiding raw oysters entirely. For wound care, all cuts and scrapes should be kept clean and covered when in contact with coastal waters. For norovirus, handwashing with soap and water, not sanitizer, is critical. For the industry and regulators, continued surveillance for antimicrobial resistance in Shigella and monitoring of Vibrio in warming coastal waters are essential. Food safety is not only about avoiding the headline-grabbing pathogens; it requires vigilance across the full spectrum of organisms that cause human illness.
