Foodborne Illnesses

Most foodborne illnesses are caused by only a handful of bacterial species. The similarity in the major symptoms of food poisoning -- nausea, cramping, diarrhea, and vomiting -- and the microscopic size of bacteria make quick and easy diagnosis difficult. Laboratory testing is often necessary to determine the bacterial cause of a particular illness. Adding to the problem, only some species or strains of a particular kind of bacterium may be pathogenic. Some strains of Escherichia coli (E. coli for short), for example, are common intestinal bacteria, while others -- such as E. coli O157:H7 -- are deadly.

Estimated to cause over 2 million infections annually in the United States.  Estimated to cause 50 deaths annually.  Acquired primarily from contaminated chicken.  Can cause Guillain Barre Syndrome - a rare but serious paralytic disease

In terms of overall number of cases, Campylobacter is the star of the foodborne illness show. Campylobacter bacteria are the most common foodborne cause of diarrheal illness in the United States, with most infections in people caused by a single species -- Campylobacter jejuni. Public health officials estimate that over 2 million people are affected by Campylobacter infections each year in the United States. Generally these infections are self-limiting and most people recover within two to five days. In severe cases the bacterium spreads to the bloodstream and can cause life-threatening infections. Approximately 50 people die each year from Campylobacter infections. The pathogen is also linked to Guillain-Barre Syndrome, a rare but serious paralytic disease. Upwards of 40% of the cases of Guillain-Barre follow Campylobacter infections.

People acquire Campylobacter infections mainly through contaminated poultry (chicken and turkey) and unpasteurized milk. While Campylobacter jejuni does not cause disease in chickens, the bacteria are common throughout U.S. poultry flocks. They easily spread between live birds through shared water sources or feces and in the slaughterhouse. The majority of broiler chickens passing through U.S. processing plants are contaminated with Campylobacter bacteria. Some surveys estimate the percentage to be up to 80%.

Public health workers are currently concerned over the development of Campylobacter strains resistant to an important class of drugs - the fluoroquinolones. In 1995, despite opposition by the Centers for Disease Control and Prevention, the Food and Drug Administration registered the first fluoroquinolone drug for treating chicken diseases. This class of drugs contains many important and powerful drugs-of-last-resort for fighting human infections. Health care workers feared that agricultural use of this drug would hasten resistance development in Campylobacter and eventually limit treatment options.

Concerns over the registration of fluoroquinolones in food animals were warranted. A 1997 study by the Minnesota Department of Health identified increased levels of fluoroquinolone-resistant Campylobacter in chickens, turkeys, and people. Fluoroquinolone resistance in Campylobacter has continued to rise, reaching nearly 18 percent in 1999, a rate so alarming that the FDA moved in October 2000 to revoke the approvals of this drug for use in poultry.

Results in nearly 1.4 million cases annually in the United States.  Estimated to cause 600 deaths annually.  Acquired mainly from beef, poultry, pork, and eggs.  Associated with widespread multi-drug resistance. Although not nearly as common as Campylobacter, Salmonella infections are serious causes of foodborne illness. Every year, approximately 40,000 cases of Salmonella are reported in the United States. As many milder cases are not diagnosed or reported, the Centers for Disease Control and Prevention (CDC) estimates that the actual number of infections may be 38 times greater. Typically Salmonella infections do not require medical treatment and the illness usually lasts 4 to 7 days. In some people, however, the diarrhea may be so severe that the patient needs to be hospitalized. The CDC estimates that there are as many as 18,000 hospitalizations, 5,000 bloodstream infections, and 600 deaths associated with Salmonella poisoning each year in the United States. People usually obtain Salmonella by eating contaminated beef, poultry, eggs, or vegetables tainted with animal feces. Results from monitoring programs at slaughterhouses suggest that 20% of the broiler chickens in the United States are contaminated with harmful Salmonella strains. The health care community is concerned about the emergence of drug-resistant strains of Salmonella. High rates of drug-resistant -- including multidrug-resistant -- bacteria have been documented in meat and poultry, as has the transmission of drug resistant pathogens from animals to people. One especially worrisome strain of Salmonella, DT104, is now resistant to five important antibiotics used in human medicine. And while Salmonella contamination in the food supply has dropped in recent years, the prevalence of multidrug-resistant DT104 isolates has increased in the United States from less than 1 percent in 1980 to 34 percent in 1996. sources

Estimated to cause 73,000 cases annually in the United States.  Estimated to cause over 60 deaths annually.  Acquired primarily through ground beef.  Antibiotics are not recommended for treatment. Hundreds of strains of Escherichia coli (E. coli) bacteria reside harmlessly in the gut of healthy people and animals, only a few of which are associated with foodborne illnesses. One strain -- O157:H7 -- produces a powerful toxin and can cause severe illness (the combination of letters and numbers in the name is part of the classification system used by scientists to distinguish one strain of E. coli from another). Each year in the United States an estimated 73,000 people suffer from E. coli O157:H7 infections, but in most cases the disease is self-limiting after 1 to 3 days. In about 5% of infections, there are complications -- including kidney damage. Approximately 60 people die each year from this bacterium. Most infections of E. coli O157:H7 come from eating undercooked, contaminated ground beef. Meat becomes contaminated in the slaughterhouse, and the bacteria are easily spread when meat is ground in the processing plant. Studies have show that about half the cattle in feedlots carry this pathogen during summer months. Other sources of infection include lettuce, unpasturized milk and juice, and contaminated water. The bacteria are also readily passed between people, particularly among toddlers, if hygiene or handwashing habits are poor. Giving antibiotics is not essential for an E. coli O157:H7 infection. Some experts feel that prescribing antibiotics may even be harmful, as these drugs may precipitate kidney complications. Antibiotic-resistant strains of E. coli O157:H7 in humans are correlated with antibiotic use in cattle. sources

Strictly speaking, Enterococcus is not a foodborne pathogen, but because livestock can serve as reservoirs for drug-resistant strains of Enterococcus which may enter the human food chain, and because the bacterium is recognized as the leading cause of many serious hospital infections, UCS has included this bacterium in our rogue s gallery.

Species of Enterococcus are found in the intestine of nearly all animals from cockroaches to people and are readily encountered outdoors on vegetables and in water, probably due to contamination by animal waste or untreated sewage. Two strains are normally associated with illness in people: Enterococcus faecalis and Enterococcus faecium (the more common of the two).

Enterococcus faecium readily develops resistance to antibiotics. This bacterium's resistance to two important drugs -- vancomycin and ampicillin -- has increased alarmingly over the past few years. In 1997, 52% and 83% of isolates sampled in the United States were vancomycin and ampicillin resistant, respectively.

The development of vancomycin resistance in Enterococcus demonstrates some of the complexity of drug use and the rise in antibiotic resistance around the world. While vancomycin-resistant Enterococcus (VRE) is prevalent in Europe and the United States, the development of resistance on the two continents is thought to have occurred by different mechanisms. In Europe the rise of VRE is linked to the use of the antibiotic avoparcin as a growth promoter in food animals. There, VRE is found throughout the community, the food supply and urban and rural sewage systems. In the United States avoparcin is not approved for use in food animals, but vancomycin is routinely used in hospitals to treat bacterial infections. In the United States, VRE is rampant in hospitals, but is nearly absent outside medical facilities.

There is a new concern in the United States over the development of drug resistance in Enterococcus faecium that mirrors the European scenario of VRE development. The drug virginiamycin (a streptogramin) has been used in food animals for over 26 years in the United States. When FDA approved the related streptogramin Synercid for use in people in 1999, the drug was considered a last line of defense for treating VRE. But experts fear that the prior agricultural use of virginiamycin has generated Enterococci that are resistant to the streptogramins. And evidence suggests that such worry is warranted. Synercid resistance has already been documented in about 4 percent of the patients with VRE who have received Synercid.

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Estimated to cause nearly 500,000 cases annually in the United States.  About 3% of persons infected with one kind of Shigella will later develop Reiter's syndrome.  Contaminated water and food are often the source of infection.  Some strains are becoming resistant to antibiotics.

Shigella is a disease that originates from fecal matter. Infections may be acquired from eating food or from drinking or swimming in water contaminated with human or animal waste. As Shigella passes easily between infected people, nursing homes and day-care centers are places where outbreaks often occur. Inadequate handwashing is frequently cited as the vehicle of spread

While Shigella infections can usually be treated with antibiotics, health experts suggest that these drugs should be used selectively to treat only the more severe cases. Some strains of this bacterium are becoming resistant to antibiotics. The CDC has documented increasing resistance to available antibiotics in domestically acquired infections.

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The bacterium Listeria monocytogenes has recently been recognized as an important public health problem in the United States. While less widely know than other foodborne pathogens like Salmonella and E. coli, it is far more deadly. An estimated 2,500 people become seriously ill from Listeria each year in the United States with infections often leading to blood poisoning or meningitis. Most at risk from this pathogen are pregnant women, newborn children, and people with weakened immune systems.

Listeria is found throughout nature, in animals, plants, water, and soil. Vegetables can become contaminated from the soil or from manure used as fertilizer, and the bacterium can contaminate unpasteurized dairy products such as soft cheese.Listeria is mostly a problem with ready-to-eat foods, filling a unique niche among foodborne pathogens. Ubiquitous in nature and able to thrive in cool environments, this pathogen can easily spread into a processing plant and then contaminate and multiply on the sterile surfaces of processed foods. The long shelf life of processed foods allows time for bacterial populations to grow, increasing the chances of people becoming ill from this pathogen.

The development of drug-resistance in Listeria from antibiotic use in farm animals is less of a concern than with other foodborne pathogens. Experts believe that the population of Listeria bacteria found in the intestines of food animals is often not the same that ultimately contaminates ready-to-eat foods. Listeria is also a poor competitor against other human pathogens such as E. coli orCampylobacter and is not likely to build population levels high enough to cause an infection in people. Antibiotics can be effective in treating illness caused byListeria if the infection is caught soon enough. So far, drug resistance in Listeria is not a problem.

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Sources

Campylobacter

Centers for Disease Control and Prevention, Health Topics A to Z.
http://www.cdc.gov/ncidod/dbmd/diseaseinfo/

Food and Drug Administration. 2000. Notice of Opportunity for Hearing (NOOH) -- Docket No. 00N-1571, CVM 76. Enrofloxacin for Poultry; Opportunity For Hearing. pp 64954-64965 [FR Doc. 27832]. http://www.fda.gov/OHRMS/DOCKETS/98fr/103100a.pdf

General Accounting Office. 1999. Food Safety: The Agricultural Use of Antibiotics and Its Implications for Human Health. Report to the Honorable Tom Harkin, Ranking Minority Member, Committee of Agriculture, Nutrition, and Forestry, U.S. Senate. GAO/RCED-99-74, April 1999. Washington.

Mead, P.S., et al. 2000. Food Related Illness and Death in the United States. Emerging Infectious Diseases [serial online], 5(5).

Smith, K.E., et al. 1999. Quinolone-resistant Campylobacter jejuni infections in Minnesota, 1992-1998. New England Journal of Medicine, 20(340): 1525-1532.

Salmonella

Centers for Disease Control and Prevention, Health Topics A to Z.
http://www.cdc.gov/ncidod/dbmd/diseaseinfo/

General Accounting Office. 1999. Food Safety: The Agricultural Use of Antibiotics and Its Implications for Human Health. Report to the Honorable Tom Harkin, Ranking Minority Member, Committee of Agriculture, Nutrition, and Forestry, U.S. Senate. GAO/RCED-99-74, April 1999. Washington.

Glynn, M.K., et al. 1998. Emergence of multidrug-resistant Salmonella enterica serotype Typhimurium DT104 infections in the United States. New England Journal of Medicine, 338(19): 1333-1338.


E-coli

Centers for Disease Control and Prevention, Health Topics A to Z.
http://www.cdc.gov/ncidod/dbmd/diseaseinfo/

General Accounting Office. 1999. Food Safety: The Agricultural Use of Antibiotics and Its Implications for Human Health. Report to the Honorable Tom Harkin, Ranking Minority Member, Committee of Agriculture, Nutrition, and Forestry, U.S. Senate. GAO/RCED-99-74, April 1999. Washington.

Mead, P.S., et al. 2000. Food Related Illness and Death in the United States. Emerging Infectious Diseases [serial online], 5(5).


Enteroccous

Food and Drug Administration. Risk Assessment of the Public Health Impact of Streptogramin Resistance in Enterococcus faecium Attributable to the Use of Streptogramins in Animals; Request for Comments and for Scientific Data and Information. Federal Register 65(76): 20992-20995. April 19, 2000.

Huycke, M.M., et al. 1998. Multiple-Drug Resistant Enterococci: The Nature of the Problem and an Agenda for the Future. Emerging Infectious Diseases. 4(2): 239-249.

McDonald, L.C., et al. 1997. Vancomycin-Resistant Enterococci Outside the Health-Care Setting: Prevalence, Sources, and Public Health Implications. Emerging Infectious Diseases. 3(3): 311-317.


Shigella

Centers for Disease Control and Prevention, Health Topics A to Z.
http://www.cdc.gov/ncidod/dbmd/diseaseinfo/


Listeria

Centers for Disease Control and Prevention, Health Topics A to Z. 

Mead, P.S., et al. 2000. Food Related Illness and Death in the United States. Emerging Infectious Diseases [serial online], 5(5). 

Perl, B. 2000. Poisoned Package. The Washington Post Magazine. January 16.