P athogens are disease-causingmicroorganisms that includebacteria, fungi, parasites, and

viruses. Pathogens can cause illnessthrough contaminated food, contam-inated water, or person-to-personcontact. Most foodborne illnessestypically have a rapid onset and areself-limiting. Common symptomsare gastrointestinal problems andvomiting. Foodborne illnesses rangefrom mild to severe; some of themore severe cases can result in pre-mature death.

U.S. Food and Drug Administra-tion (FDA) researchers estimate that1 to 3 percent of all foodborne-ill-ness cases later develop secondaryillnesses or complications that canoccur in any part of the body, in-cluding the nerves, joints, and heart.These complications may be chronicand may cause premature death. Forexample, Guillain-Barré syndrome, amajor cause of nontrauma neuro-muscular paralysis in the UnitedStates, may follow a small percent-age of Campylobacter infections. Inrare cases, Salmonella, like manyother bacterial and parasitic infec-tions, can cause chronic disease syn-dromes, such as arthritis and menin-gitis. Societal costs have not been es-timated for the vast majority of

complications associated with food-borne illnesses.

Each year, seven foodbornepathogens—Campylobacter jejuni,Clostridium perfringens, E. coliO157:H7, Listeria monocytogenes, Sal-monella, Staphylococcus aureus, andToxoplasma gondii (see box on sevenfoodborne illnesses)—cause an esti-mated 3.3 million to 12.3 millioncases of foodborne illness in theUnited States and up to 3,900deaths. Last year, USDA’s EconomicResearch Service (ERS) estimatedthat these seven foodborne illnessescost society $5.6 billion to $9.4 bil-lion (in 1993 dollars) in medicalcharges and lost productivity.Knowledge on the extent and sever-ity of these illnesses is still growing,and estimates need to be updated asbetter data become available. Thisarticle updates those 1993 cost esti-mates and:

• Uses more recent data, whereavailable, on annual foodborne-illness cases and deaths;

• Uses 1995 medical costs and wagerates; and

• Improves the consistency of calcu-lations across all pathogens.

Researchers at the Centers forDisease Control and Prevention(CDC) estimate that listeriosis caseshave fallen by 44 percent in the lastdecade because of educational, in-dustry, and regulatory efforts to re-

duce Listeria contamination of foodsand subsequent illnesses. The lowerbound estimate reflects the decreasein listeriosis cases (table 1). The truenumber of annual listeriosis casesand deaths is still underestimatedbecause only hospitalized cases areincluded, due to data limitations.Campylobacteriosis cases are alsoreported as a range to reflect uncer-tainty in the estimates, which is sim-ilar to other diseases in this analysis.The death rate for S. aureus intoxica-tions was decreased from 0.08 per-cent to 0.03 percent on the advice ofCDC researchers. The range of 800-4,000 salmonellosis deaths was alsoreplaced by updated estimates of1,000-2,000 deaths.

This update also includes a sec-ond set of cost-of-illness estimatesthat use less conservative values of astatistical life (a generic monetaryvalue for an unidentified individual)as a proxy for the societal costs ofsomeone who dies prematurely orwho is unable to work because of afoodborne illness.

Calculating the Costs ofFoodborne Illness

The cost-of-illness estimates arecalculated from the number of an-nual foodborne-illness cases anddeaths caused by the seven food-borne illnesses described in this arti-

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Food Safety

ERS Updates U.S.Foodborne Disease Costs

for Seven Pathogens Jean C. Buzby and Tanya Roberts

(202) 219-0905 (202) 219-0857

The authors are economists with the Food andConsumer Economics Division, Economic ResearchService, USDA.

cle; the number of cases that de-velop secondary complications; andthe corresponding medical costs,lost productivity costs, and other ill-ness-specific costs, such as specialeducation and residential-care costs(table 2).

In general, for each foodborne ill-ness, cases were divided into fourseverity groups: those who did notvisit a physician, those who visited a

physician, those who were hospital-ized, and those who died prema-turely because of their illness. Foreach severity group, medical costswere estimated for physician andhospital services, supplies, medica-tions, and special procedures uniqueto treating the particular foodborneillnesses. Such costs reflect the num-ber of days/treatments of a medicalservice, the average cost per service,and the number of patients receiv-ing such service.

Most people with foodborne ill-nesses miss a day or so of work.This lost productivity is approxi-mated by wage rates, published bythe Bureau of Labor Statistics. How-ever, some patients die and somedevelop complications so that theyeither never return to work, regainonly a portion of their pre-illnessproductivity, or switch to less de-manding and lower paying jobs. Thetotal cost of lost productivity is the

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Campylobacter jejuniCampylobacteriosis ranges from a

mild illness with diarrhea lasting aday, to severe abdominal pain, se-vere diarrhea (sometimes bloody),sometimes accompanied by fever, oc-casionally lasting for several weeks.The incubation period for most casesis 2 to 5 days, and the illness usuallylasts from 2 to 10 days, dependingon its severity. Although the illness isgenerally regarded as a relativelymild disease, death can occur insome cases, especially for the veryyoung, very old, or immunocompro-mised.

Clostridium perfringensC. perfringens intoxication typi-

cally occurs 6 to 24 hours after inges-tion of food that bears large countsof this bacteria. The illness in hu-mans is frequently a mild gastroin-testinal distress, lasting only arounda day. Deaths are uncommon.

Escherichia coli O157:H7E. coli O157:H7 disease usually a

mild gastrointestinal illness that oc-curs 3 to 5 days after eating contami-nated food. Severe complications,however, can arise. Hemorrhagic col-itis is distinguished by the suddenonset of severe abdominal cramps,little or no fever, and diarrhea thatmay become grossly bloody. Al-though less than 5 percent of E. coli

O157:H7 disease cases develop he-molytic uremic syndrome (HUS), itis a severe, life-threatening illness.HUS is a disease characterized byred blood-cell destruction, kidneyfailure, and neurological complica-tions, such as seizures and strokes.Most HUS cases are children under 5years old, although the feeble elderlymay also be at risk.

Listeria monocytogenesListeriosis may be either mild or

severe. Milder cases are character-ized by a sudden onset of fever, se-vere headache, vomiting, and otherinfluenza-type symptoms. Listeriosismay appear mild in healthy adultsand more severe in fetuses, the el-derly, and the immunocompromised.Outbreak data show that the incuba-tion period ranges from 3 to 70 days.Women infected with Listeria duringpregnancy may transmit the infec-tion to the fetus, possibly leading tostillbirths or babies born with mentalretardation.

SalmonellaSalmonellosis usually appears 6

to 74 hours after eating contami-nated food and lasts for a day ortwo. Common symptoms are nausea,diarrhea, stomach pain, and some-times vomiting. Although the illnessis generally regarded as a relativelymild disease, death can occur in

some cases, especially for the veryyoung, very old, or immunocompro-mised.

Staphylococcus aureusS. aureus intoxication usually

occurs within 1 to 6 hours followingconsumption of the toxins producedby the bacteria, but it may occurwithin 30 minutes. Illness caused byS. aureus enterotoxin is characterizedby severe nausea, vomiting, cramps,and diarrhea. Although the illnessgenerally does not last longer than 1or 2 days, the severity of the illnessmay indicate the need for hospital-ization.

Toxoplasma gondiiToxoplasmosis can cause mild flu-

like symptoms, though most peopleinfected with the parasite do nothave any symptoms. People vary intheir risk of getting sick from thisparasite. People with suppressed im-mune systems, such as AIDS andcancer patients, face higher risks.One outbreak associated with under-cooked meat indicates that the incu-bation period ranges from 10 to 23days. Women infected with T. gondiiduring pregnancy may transmit theinfection to their fetus, possibly lead-ing to stillbirths or babies born withbirth defects ranging from hearing orvisual impairments to mental retar-dation.

Study Considers Seven Foodborne Illnesses

sum for all individuals affected, in-cluding the patients and, in the caseof ill children, their parents or paidcaregivers.

Calculating the Value ofa Statistical Life

ERS now uses two different ap-proaches to estimate the value of a

statistical life (see box). The first ap-proach estimates the value of a sta-tistical life by using records indicat-ing consumers’ willingness to pay toreduce the risks of death and poorhealth. The hedonic-wage approachuses labor market data to estimateconsumers’ willingness to pay. Con-sumers, often subconsciously, placea value on life and health when they

earn higher wages in jobs that incurrisks. Typically, employers mustoffer workers higher wages to in-duce them to take such a job, as op-posed to similar jobs with no suchrisks.

W. Kip Viscusi, an economist withDuke University, compared wagedifferences in 24 wage-risk studiesand found that the extra wages asso-

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Food Safety

Table 1Not All Illnesses and Deaths From These Pathogens Are From Food Sources

Estimated Estimated EstimatedPathogen and total annual total annual share

disease/complication cases deaths foodborne

Number Number Percent

Bacteria:

Campylobacter jejuni or coliCampylobacteriosis 2,000,000-10,000,000 200-730 55-70

Clostridium perfringensC. perfringens intoxications 10,000 100 100

Escherichia coli O157:H7E. coli O157:H7 disease 10,000-20,000 100-250 80Hemolytic uremic syndrome1 400-820 120-291 80Subtotal N/A 220-541 N/A

Listeria monocytogenes2

Listeriosis 1,092-1,860 270-510 85-95Complications 26-43 0 85-95Subtotal N/A 270-510 N/A

Salmonella (non-typhoid)Salmonellosis 800,000-4,000,000 1,000-2,000 87-96

Staphylococcus aureusS. aureus intoxications 8,900,000 2,670 17

Parasite:

Toxoplasma gondii3

Toxoplasmosis 435 79 50Complications 3,083 0 50Subtotal 3,162 79 N/A

Total4 11,700,000-22,900,000 4,500-6,600 N/A

Notes: N/A = Not applicable. 1Kidney failure. 2Includes only hospitalized patients because of data limitations. 3Includes only toxoplas-mosis cases related to fetuses and newborn children who may become blind or mentally retarded. 435 develop severe acute illness atbirth, of which 79 die and 356 survive acute illness but develop complications by age 17. In addition to these 356 acute cases withcomplications, 2,727 cases do not have noticeable acute illness at birth but develop complications by age 17 for a total of 3,083 withcomplications. Does not include all other cases of toxoplasmosis. Another high-risk group for this parasite is the immunocompromised,such as patients with AIDS. 4Totals are rounded down to reflect the uncertainty of the estimates.

ciated with the increased overallhazard of one death from risky jobsare between $3 million and $7 mil-lion (in 1990 dollars). Several regula-tory agencies use either Viscusi’srange of estimates or the $5 millionmidpoint when analyzing the bene-

fits of proposed public-safety rules.The $5 million midpoint value for astatistical life estimate was used forthe cost estimates in table 2.

The second approach to estimatethe value of a statistical life focusesprimarily on lost productivity. For

those who die or are unable to re-turn to work, this lost productivityis calculated using a combination ofhuman-capital and willingness-to-pay estimates developed by J.Steven Landefeld and Eugene Se-skin of the U.S. Department of Com-

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Table 2

Toxoplasma gondii, Campylobacter, and Salmonella Are the Most Costly Foodborne Pathogens1

Estimated foodborne illness Pathogen and Estimated foodborne illness— costs, assuming—

disease/complication Cases Deaths $5 million per life2 Landefeld & Seskin3

Number Billion dollars

Bacteria:

Campylobacter jejuni or coliCampylobacteriosis 1,100,000-7,000,000 110-511 1.2-6.6 .7-4.3

Clostridium perfringensC. perfringens intoxications 10,000 100 .5 .1

Escherichia coli O157:H7E. coli O157:H7 disease 8,000-16,000 80-200 .4-1.0 .1-.3Hemolytic uremic syndrome4 320-656 96-233 .5-1.2 .2-.4Subtotal N/A 176-433 .9-2.2 .3-.7

Listeria monocytogenes5

Listeriosis 928-1,767 230-485 1.2-2.2 .12-.25Complications 22-41 0 .1-.2 .03-.05Subtotal N/A 230-485 1.3-2.4 .1-.3

Salmonella (non-typhoid)Salmonellosis 696,000-3,840,000 870-1,920 4.8-12.2 .9-3.5

Staphylococcus aureusS. aureus intoxications 1,513,000 454 3.3 1.2

Parasite:

Toxoplasma gondii 6

Toxoplasmosis 217 40 .1 .04Complications 1,541 0 7.6 3.15Subtotal 1,581 40 7.7 3.2

Total7 3,300,000-12,300,000 1,900-3,900 19.7-34.9 6.5-13.3

Notes: N/A = Not applicable. 1Cost estimates are in 1995 dollars. 2The $5 million value of a statistical life was estimated from wage-riskstudies. 3This human-capital approach, increased by a willingness-to-pay multiplier, estimates the value of a statistical life, dependingon age, to range from roughly $15,000 to $1,979,000 in 1995 dollars. 4Kidney failure. 5Includes only hospitalized patients because ofdata limitations. 6Includes only toxoplasmosis cases related to fetuses and newborn children who may become blind or mentally re-tarded. 217 cases develop severe acute illness at birth, of which 40 die and 177 survive acute illness but develop complications by age17. In addition to these 177 acute cases with complications, 1,364 cases do not have noticeable acute illness at birth but developcomplications by age 17 for a total of 1,541 foodborne illness cases with complications. Does not include all other cases of toxoplas-mosis. Another high-risk group for this parasite is the immunocompromised, such as patients with AIDS. 7Totals are rounded down to reflect the uncertainty of the estimates.

merce. Human-capital estimates arethe value in today’s dollars of an in-dividual’s lifetime stream of incomeif the illness had not occurred. Thehuman-capital estimates are in-creased by a multiplier that capturespeople’s willingness to pay to avoiddeath, as reflected in life insurancepremiums. These estimates of thevalue of a statistical life range, de-pending on age, from roughly$15,000 to $1,979,000 (in 1995 dol-lars). The major limitation of this ap-proach is that it does not fully con-sider the value that individuals mayplace on (and pay for) feeling

healthy, avoiding pain and suffering,or using their free time. Because theapproach does not cover all of thesevaluable aspects of health, the ap-proach is generally thought to un-derstate the true societal costs.

ERS uses both approaches herebecause economists have notreached a consensus on which esti-mates to use, though they may nowbe leaning toward the hedonic-wageapproach. Previously, ERS used theLandefeld and Seskin estimates incost-of-illness analyses becausethese estimates are more conserva-tive and provide values for patientsof different ages, instead of onevalue for patients of all ages.

High Costs of FoodborneIllness

When Landefeld and Seskin’svalue of a statistical life estimateswere used in the cost-of-illnessanalyses, total annual costs of theseven foodborne illnesses ranged be-tween $6.5 and $13.3 billion. Usingthe $5 million value of a statisticallife estimate from the hedonic-wagestudies, total annual costs rangedbetween $19.7 and $34.9 billion.

Both sets of estimates undervaluethe true costs of foodborne illnessesto society, however, because theanalyses covered only sevenpathogens—there are over 40 differ-ent foodborne pathogens believed tocause human illnesses. Estimatedcosts would also increase if the costsfor all complications linked to food-borne illnesses, such as arthritis,meningitis, or Guillain-Barré syn-drome, were included. Costs wouldincrease even further if monetaryvalue were placed on public-safetyrisk reductions for those who do notbecome ill.

Government EffortsImprove Food Safety

FDA, CDC, and USDA’s FoodSafety and Inspection Service (FSIS)are currently collaborating on an ac-tive surveillance project to improveestimates of the pathogens responsi-ble for diarrheal disease and to iden-tify risk factors that increase or de-crease the chances of becoming ill.Better information can be used toimprove the design of control pro-grams. Salmonella and Escherichia coliO157:H7 (E. coli O157:H7) will bethe first target, followed by addi-tional pathogens as the study ex-pands.

FSIS’s Hazard Analysis and Criti-cal Control Point (HACCP) final rulewas released in July 1996 to enhancethe safety of meat and poultry.

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Food Safety

Hedonic-wage approach:• Estimated from hedonic-wage

studies, which use labor marketdata on how much employersmust offer workers, in terms ofhigher wages, to induce workersto take a job with some injuryrisks, as opposed to a similar jobwith no such risks.

• Estimated value of saving a life is$5 million for each life in 1995dollars, regardless of age.

• These studies produce more us-able estimates for mortality risksthan they do for risks of tempo-rary or chronic illnesses.

The hedonic-wage approach mostlikely excludes government and in-dustry costs as well as other coststhat individuals may not considerwhen deciding to accept a risky job.

Landefeld and Seskin’s humancapital/willingness-to-pay(WTP) approach:

• Generates the present value of ex-pected lifetime after-tax incomeand housekeeping services at a 3-percent real rate of return, ad-justed for an annual 1-percent in-crease in labor productivity and arisk-aversion factor of 1.6. The

risk-aversion factor is based onthe ratio of life-insurance pre-mium payments to life-insuranceloss payments. In most cases, lifeinsurance premiums represent“household WTP for potentiallosses associated with the deathof an income-earning householdmember.”

• Estimates the value of a statisticallife, depending on age, to rangefrom roughly $15,000 to$1,979,000 in 1995 dollars.

This more conservative approachunderestimates the true costs offoodborne illnesses to society be-cause it excludes costs, such as:

• Pain, suffering, and lost leisuretime of the patient and family;

• Lost business and costs and liabil-ities of lawsuits affecting agricul-ture and the food industry;

• The value of self-protective be-haviors undertaken by industryand consumers;

• Resources spent by Federal, State,and local governments to investi-gate the source and epidemiologyof the outbreak; and

• The value of reducing risks forpeople who do not become ill.

Estimating the Value of a Statistical Life

Under HACCP, all meat and poultryslaughtering and processing plantsmust examine their operations andidentify the hazards and the specificpoints that pose the greatest foodsafety risks. To ensure control ofphysical, biological, or chemical haz-ards, the plants will then establishcritical limits for preventive mea-sures associated with each identifiedpoint. There are also steps for moni-toring, recordkeeping, and verifying,which include some testing of meatand poultry for microbial contami-nation to ensure that the HACCPsystem is meeting safety targets.Both the plants and FSIS are respon-sible for verifying the effectivenessof HACCP.

FSIS’s HACCP intervention willbe phased in over a 3-year period,with larger plants expected to com-ply sooner than small plants. FDApromulgated a similar HACCP rulefor seafood in December 1995. Bothrules strengthen the ongoing efforts

of industry and Government to re-duce the number of U.S. foodborneillness cases and deaths.

ReferencesBuzby, Jean C., and Tanya

Roberts. “ERS Estimates FoodborneDisease Costs,” FoodReview, USDA,Economic Research Service, Vol. 18,Issue 2, May-Aug. 1995, pp. 37-42.

Buzby, Jean C., Tanya Roberts, C.-T. Jordan Lin, and James M. Mac-Donald. Bacterial Foodborne Disease:Medical Costs and Productivity Losses,AER-741. USDA, Economic ResearchService. Aug. 1996.

Council for Agricultural Scienceand Technology. Foodborne Pathogens:Risks and Consequences, Task ForceReport No. 122. Washington, DC.Sept. 1994.

Landefeld, J. Steven, and EugeneP. Seskin. “The Economic Value ofLife: Linking Theory to Practice,”American Journal of Pubic Health, Vol.6, 1982, pp. 555-66.

“Pathogen Reduction; HazardAnalysis and Critical Control Point(HACCP) Systems, Final Rule,” Fed-eral Register, Vol. 61, No. 144, July 25,1996, pp. 38805-989.

“Preliminary Regulatory ImpactAssessment for Docket No. 93-016P—Pathogen Reduction; HazardAnalysis and Critical Control Point(HACCP) Systems,” Federal Register,Vol. 60, No. 23, Feb. 3, 1995, pp.6774-889.

“Procedures for the Safe and Sani-tary Processing and Importing ofFish and Fishery Products: FinalRule,” Federal Register, Vol. 60, No.242, Dec. 18, 1995, pp. 65095-200.

Viscusi, W.K. “The Value of Risksto Life and Health,” Journal of Eco-nomic Literature, Vol. 31, Dec. 1993,pp. 1912-46.

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