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Facts About Foodborne Bacteria, Viruses, & Parasites in the United States

The CDC estimates 48 million people get sick, 128,000 are hospitalized, and 3,000 die from foodborne diseases each year in the United States.

Most foodborne illnesses were caused by norovirus (over 60%), followed by Salmonella, Clostridium perfringens, Campylobacter and Staphylococcus aureus. Leading causes of hospitalization were Salmonella, followed by norovirus, Campylobacter, Toxoplasma gondii and E. coli O157. Leading causes of death were Salmonella, Toxoplasma gondii, Listeria monocytogenes, norovirus, and Campylobacter

The CDC estimates that 59% of foodborne illnesses were caused by viruses, 39% by bacteria, and 2% by parasites.

64% of hospitalizations were caused by bacteria, 27% by viruses, and 9% by parasites.

64% of deaths were caused by bacteria, 25% by parasites, and 12% by viruses.

The CDC tracks 31 pathogens transmitted commonly by food in the United States.


Bacillus cereus - Bacillus cereus is a Gram-positive, rod-shaped, facultatively anaerobic, motile, beta-hemolytic, spore forming bacterium commonly found in soil and food.

Brucella - Brucella is a genus of Gram-negative bacteria. They are small, nonencapsulated, nonmotile, facultatively intracellular coccobacilli. Brucella spp. are the cause of brucellosis, which is a zoonosis transmitted by ingesting contaminated food, direct contact with an infected animal, or inhalation of aerosols.

Campylobacter - Campylobacter is a genus of Gram-negative bacteria. Campylobacter typically appear comma- or s-shaped and are motile. Some Campylobacter species can infect humans, sometimes causing campylobacteriosis, a diarrheal disease in humans. Campylobacteriosis is usually self-limiting and antimicrobial treatment is often not required, except in severe cases or immunocompromised patients.

Clostridium botulinum - Clostridium botulinum is a Gram-positive, rod-shaped, anaerobic, spore-forming, motile bacterium with the ability to produce the neurotoxin botulinum. The botulinum toxin can cause botulism; a severe flaccid paralytic disease in humans and other animals and is the most potent toxin known to humankind, natural or synthetic, with a lethal dose of 1.3–2.1 ng/kg in humans.

Clostridium perfringens - Clostridium perfringens is a Gram-positive, rod-shaped, anaerobic, spore-forming pathogenic bacterium of the genus Clostridium. C. perfringens is ever-present in nature and can be found as a normal component of decaying vegetation, marine sediment, the intestinal tract of humans and other vertebrates, insects, and soil.

E. coli O157 - Escherichia coli O157, sometimes called VTEC or STEC, is a bacterial infection that can cause severe stomach pain, bloody diarrhea, and kidney failure.

STEC non-O157 - There are numerous non-O157 STEC serogroups that often cause illness in people in the United States. The most common serogroups reported to cause foodborne illness in the United States are O26, O111, O103, O121, O45, and O145. These six serotypes account for about 75% of all STEC infections in human in the U.S.

ETEC - Enterotoxigenic Escherichia coli (E. coli), or ETEC, is an important cause of bacterial diarrheal illness. Infection with ETEC is the leading cause of travelers’ diarrhea and a major cause of diarrheal disease in lower-income countries, especially among children.

Listeria monocytogenes - Listeria monocytogenes is the species of pathogenic bacteria that causes the infection listeriosis. It is a facultative anaerobic bacterium, capable of surviving in the presence or absence of oxygen. It can grow and reproduce inside the host's cells and is one of the most virulent foodborne pathogens: 20 to 30% of foodborne listeriosis infections in high-risk individuals may be fatal.

Mycobacterium bovis- Mycobacterium bovis (M. bovis) is another mycobacterium that can cause TB disease in people. M. bovis is most commonly found in cattle and other animals such as bison, elk, and deer. In people, M. bovis causes TB disease that can affect the lungs, lymph nodes, and other parts of the body.

Salmonella, nontyphoidal - Nontyphoidal Salmonella are a leading cause of foodborne disease in humans worldwide. While gastroenteritis is the most common presentation in healthy adults, systemic disease can also occur, particularly in those who are immunocompromised including children and the elderly.

S. enterica serotype Typhi - Typhoid fever is caused by Salmonella enterica serotype Typhi (S. typhi). These highly infectious bacteria rapidly and effectively pass through the intestinal tract of the human host and can be transmitted to other people through the fecal-oral route. Infection may result in bacteremia and acute febrile illness.

Shigella - Shigella are bacteria that cause shigellosis, also known as bacillary dysentery. They are a highly infectious organism, with foodborne outbreaks often involving infected food handlers. Unlike other common foodborne pathogens, humans are the only natural hosts.

Staphylococcus aureus - Staphylococcus aureus is a common cause of foodborne illness that is not covered in some epidemiologic surveillance programs. Some strains of Staphylococcus aureus cause staphylococcal food poisoning through production of heat-stable staphylococcal toxins.

Streptococcus - Streptococcus is a Gram-positive foodborne pathogen that can cause foodborne disease.

Vibrio cholerae, toxigenic - Cholera is an acute, diarrheal illness caused by infection of the intestine with the toxigenic bacterium Vibrio cholerae serogroup O1 or O139.

V. vulnificus - V. vulnificus is an extremely virulent bacterium that can cause three types of infections: Acute gastroenteritis from eating raw or undercooked shellfish: V. vulnificus causes an infection often incurred after eating seafood, especially raw or undercooked oysters. It does not alter the appearance, taste, or odor of oysters.

V. parahaemolyticus - V. parahaemolyticus is a germ in the same family as the bacteria that cause cholera. It naturally lives in coastal waters in the United States and most commonly causes an infection of the bowel in humans but can also result in wound and blood infections.

Yersinia enterocolitica - Y. enterolitica are the most common species causing human intestinal yersiniosis. Pigs are the major animal reservoir for the few strains of Y. enterocolitica that cause human illness, but rodents, rabbits, sheep, cattle, horses, dogs, and cats also can carry strains that cause human illness.


Cryptosporidium - Cryptosporidium, sometimes informally called crypto, is a genus of apicomplexan parasitic alveolates that can cause a respiratory and gastrointestinal illness (cryptosporidiosis) that primarily involves watery diarrhea (intestinal cryptosporidiosis) with or without a persistent cough (respiratory cryptosporidiosis) in both immunocompetent and immunodeficient humans.

Cyclospora cayetanensis - Cyclospora cayetanensis is a coccidian parasite that causes a diarrheal disease called cyclosporiasis in humans and possibly in other primates. C. cayetanensis has emerged as an endemic cause of diarrheal disease in tropical countries and a cause of traveler's diarrhea and food-borne infections in developed nations.

Giardia intestinalis - Giardia duodenalis, also known as Giardia intestinalis and Giardia lamblia, is a flagellated parasitic microorganism, that colonizes and reproduces in the small intestine, causing a diarrheal condition known as giardiasis.

Toxoplasma gondii - Toxoplasma gondii is an obligate intracellular parasitic protozoan that causes toxoplasmosis. Found worldwide, T. gondii is capable of infecting virtually all warm-blooded animals, but felids, such as domestic cats, are the only known definitive hosts in which the parasite may undergo sexual reproduction.

Trichinella spp. - Trichinellosis is caused by the ingestion of undercooked meat containing encysted larvae of Trichinella species. After exposure to gastric acid and pepsin, the larvae are released from the cysts and invade the small bowel mucosa where they develop into adult worms.


Astrovirus - Astroviruses are one of several pathogens that can cause gastroenteritis in humans. The main symptom caused by astrovirus is diarrhea.

Hepatitis A virus - Hepatitis A is an inflammation of the liver caused by the hepatitis A virus (HAV). The virus is primarily spread when an uninfected (and unvaccinated) person ingests food or water that is contaminated with the feces of an infected person. The disease is closely associated with unsafe water or food or inadequate sanitation.

Norovirus - You may hear norovirus illness be called “food poisoning,” “stomach flu,” or “stomach bug.” Noroviruses are the leading cause of foodborne illness, but other germs and chemicals can also cause foodborne illness. Norovirus illness is not related to the flu, which is caused by influenza virus.

Rotavirus - Rotavirus is a very contagious virus that causes diarrhea. Before the development of a vaccine, most children had been infected with the virus at least once by age 5.

Sapovirus - Sapovirus is a genetically diverse genus of single-stranded positive-sense RNA, non-enveloped viruses within the family Caliciviridae. Together with norovirus, sapoviruses are the most common cause of acute gastroenteritis (commonly called the "stomach flu" although it is not related to influenza) in humans and other animals.

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