Trends in Food-Borne Illnesses in the United States

In 1999, the Centers for Disease Control and Prevention (CDC) spon­sored an extensive study of the number and types of food-borne ill­nesses and death occurring annually in the United States (Paul S. Mead, et al., "Food-Related Illness and Death in the United States," Emerging Infectious Diseases, September-October 1999, 607-617; since 1999 the CDC has conducted more limited studies of food-borne illnesses in a sample of 10 states only). The study's authors concluded that there are about 76 million cases of food-borne ill­ness each year in the United States, of which about 325,000 require hospitalization and 5,000 result in death. Less than half of all cases of food-borne illness (about 14 million cases) can be associated with known pathogens. Of cases in which a pathogen has been identified, three bacteria—Salmonella, Listeria, and Toxoplasma—account for 1,500 deaths per year, more than three-quarters of those for which a known pathogen is responsible. Remarkably, a large number of illnesses (62 million), hospitalizations (265,000), and deaths (3,200) are caused by pathogens that have not been identified. Authors of the study concluded, "Overall, food-borne diseases appear to cause more illnesses but fewer deaths than previously estimated." The table on pages 135-138 summarizes a few of the most common pathogens responsible for food-borne illnesses in the United States, and the number of illnesses, hospitalizations, and death caused by each, as reported by the Mead study.

Food-borne illnesses are now closely monitored and studied by various agencies of the federal and state governments. When an out­break of a food-borne illness occurs, health workers are required to report the event and its characteristics to state and/or federal health agencies. Health officials attempt to collect as much information as possible about each outbreak, including the location of the event, the

< ESTIMATED FREQUENCIES OF ILLNESSES, HOSPITALIZATIONS, AND DEATHS OF CERTAIN FOOD-BORNE PATHOGENS IN THE UNITED STATES > AGENT ILLNESSES HOSPITALIZATIONS DEATHS TOTAL          PERCENT* TOTAL           PERCENT*         TOTAL PERCENT* Bacterial Bacillus cereus 27,360               0.2 8                         0.0                 0.0 0.0 Campylo­bacter spp. 1,963,141          14.2 10,539                17.3                  99 5.5 £ coli 07 57: H7 62,458               0.5 1,843                   3.0                  52 2.9

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< ESTIMATED FREQUENCIES OF ILLNESSES, HOSPITALIZATIONS, AND DEATHS OF CERTAIN FOOD-BORNE PATHOGENS IN THE UNITED STATES (continued) p- AGENT ILLNESSES HOSPITALIZATIONS DEATHS TOTAL PERCENT* TOTAL PERCENT *         TOTAL PERCENT* Listeria monocyto- 2,493 0.0 2,298 3.8 499 27.6 genes Salmonella non-typhoidal 1,341,873 9.7 15,608 25.6 553 30.6 Streptococcus food-borne 50.920 0.4 358 0.6 0 0.0 Yersina enterocolitica 86,731 0.6 1,105 1.8 2 0.1

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< ESTIMATED FREQUENCIES OF ILLNESSES, HOSPITALIZATIONS, AND DEATHS OF CERTAIN FOOD-BORNE PATHOGENS IN THE UNITED STATES (continued) > AGENT ILLNESSES HOSPITALIZATIONS DEATHS TOTAL          PERCENT* TOTAL           PERCENT* TOTAL           PERCENT* Parasitic Crytosporidium parvum 30,000                0.2 199                      0.3 7                     0.4 Giardia lamblia 200,000              1.4 500                      0.8 1                      0.1 Toxoplasma gondii 112,500              0.8 2,500                   4.1 375                 20.7

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< ESTIMATED FREQUENCIES OF ILLNESSES, HOSPITALIZATIONS, AND DEATHS OF CERTAIN FOOD-BORNE PATHOGENS IN THE UNITED STATES (continued) >
AGENT	ILLNESSES	HOSPITALIZATIONS	DEATHS
TOTAL	PERCENT*	TOTAL	PERCENT*	TOTAL	PERCENT*
Viral
Nor walk­like viruses	9,200,000	66.6	20,000	32.9	124	6.9
Rotavirus	39,000	0.3	500	0.8	0	0.0
Astrovirus	39,000	0.3	125	0.2	0	0.0
Hepatitis A	4,170	0.0	90	0.9	4	0.2
*Percent of all food-borne illnesses Source: Paul S. Mead, et al.,"Food-Related	llness and Death in the United States,"Emerging Infectious Diseases, September-October 1999,607-617, p. 611.

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< SOME FOOD-BORNE BACTERIAL DISEASE
OUTBREAKS IN 2004 >
AGENT	STATE	NUMBER ILL	VEHICLE	LOCATION
Bacillus cereus	Conn.	11	Chicken, roasted	Senior center
Campylobacter jejuni	Iowa	32	Whole milk, unpasteur­ized	Lodge dinner event
Clostridium perfringens	Mich.	56	Spaghetti, unspecified	Private home
Escherichia coli O157: NM	Ga.	2	Alfalfa sprout	Restaurant or delicatessen
Salmonella anatum	N.Y.	108	Roast beef, other	Picnic
Salmonella	Pa.	4	Eggs, over	Restaurant or
enteritidis	easy	delicatessen
Restaurant,
Salmonella heidelberg	Calif.	78	Sandwich, turkey	delicatessen, private home, workplace
Salmonella newport	Wisc.	13	Unspecified	Nursing home
Salmonella typhimurium	Calif.	23	Turkey, un­specified	Prison
Macaroni
Shigella flexneri	N.J.	6	salad, cole­slaw, potato salad	Restaurant or delicatessen
Staphylococcus aureus	Ohio	132	Ice cream, commercial	Restaurant or delicatessen; private home
Source: Food-Borne Outbreaks due to Bacterial Etiologies, 2004. Available online. URL:
cdc.gov/foodborneoutbreaks/us_outb/fbo2004/Outbreak_Linelist_Final_
2004.pdf.

number of people involved, the dates of the incident, characteristics of those who have become ill, and laboratory results obtained during the outbreak. The table on page 139 lists a few examples of the more than 1,200 outbreaks of food-borne illness reported in the United States in 2004, the last year for which data are available.

С о 50 40 30 20 10 0 |JUIa LI1 Л    л о Q. О tn 100,0i \ e per Incidenc 1920 1930 1940 Year 1950 1960 © Infobase Publishing

Incidence of typhoid fever in the United States (cases per 100,000 population)

Researchers have observed a significant change in the pathogens most commonly involved in food-borne illnesses in the United States. At the beginning of the 20th century, the most common food-borne illnesses in the United States were typhoid fever, tuberculosis, and cholera. But improvements in food safety practices (such as the use of chlorine to purify public water supplies, better methods of food canning and preservation, and pasteurization of milk) led to dramatic decreases in the number of cases of food-borne illnesses caused by these pathogens. The graph below shows, for example, changes in the incidence of typhoid fever in the United States between 1920 and 1960. The changes shown in this graph are typical of those for other tradi­tional food-borne illnesses, like tuberculosis and cholera. (The graph ends at 1960 because the number of deaths from typhoid fever reached nearly zero in that year and has remained very low ever since.)

Changes in the etiology of food-borne illnesses have been fairly dramatic even in recent decades. Prior to the 1980s, pathogens of considerable importance today, such as E. coli 0157:H7, Listeria mono­cytogenes, and Camplyobacter jejuni, were not even recognized as possible causes of food-borne illnesses. Today, all three pathogens are known to be responsible for significant numbers of food-borne illness outbreaks.

Even since the mid-1990s, a number of new pathogens have been detected in contaminated foods. In 1996, for example, a parasite called Cyclospora cayetanensis, first observed in a shipment of rasp­berries from Guatemala, was found to be responsible for an outbreak of diarrheal illness among people who had eaten the berries. Two years later, a new strain of the bacterium Vibrio parahemolyticus was detected in oysters taken from a bed in Galveston Bay. As the 1999 Mead survey of food-borne illnesses suggests, pathogens have still not been identified for a large majority of outbreaks in the United States.