Reading a workbook using Campylobacter as an example
The Campylobacter workbook is typical for pathogens that involve complications or result in chronic illness. The Excel file for Campylobacter contains five worksheets: 1) source information and notes on how to use the worksheets; 2) mean cost of illness estimates; 3) low cost of illness estimates; 4) high cost of illness estimates; and 5) numerical assumptions used in each of the three estimates worksheets.
In the assumptions worksheet, the first three rows of data report low, mean, and high estimates of the total number of cases for each health outcome by severity in a typical year in the United States. The column headings describe specific health outcomes resulting from infection with Campylobacter. When reading the headings, the severity of health outcomes increases going from the left to right columns. The mildest cases did not seek medical care. Hospitalized cases resulted in either recovery or death. The most severe cases were hospitalized and died. The low, mean, and high case estimates for total cases, hospitalizations, deaths, and chronic illnesses are taken from Scallan et. al. (2011). Moving further to the right, additional columns provide estimates of the costs associated with potential chronic diseases that can arise from each specific pathogen, with these costs estimated on a per-case basis as well. These estimated costs of chronic diseases are not included in the acute case estimated costs and are based on Hoffmann et. al. (2025) or on synthesis of the scientific literature.
For Campylobacter, Scallan et al. (2011) reports an average (mean estimates) of 845,024 cases of illness in a typical year. Of these cases, 664,189 people did not seek medical care, 172,372 saw a physician and recovered without further medical treatment, and 8,463 were hospitalized. Of the 8,463 hospitalized cases, 8,387 recovered and 76 died. Hoffmann et. al. (2025) reports the annual incidence of long-term health effects (chronic sequelae) that develop from initial illness cases. Using mean estimates, 21,971 people experienced Reactive Arthritis (ReA), and 63,377 suffered from irritable bowel syndrome (IBS). Additionally, 304 people developed Guillain-Barré Syndrome (GBS) and 7 of those 304 GBS cases resulted in death.
Below the rows with case incidence estimates are assumptions about the costs associated with each health outcome. There are three broad classes of costs in the assumptions worksheet: 1) medical treatment costs; 2) lost productivity; and 3) individuals’ willingness to pay (WTP) to prevent the premature mortalities expected in a typical year (also referred to as the Value of a Statistical Life (VSL) (EPA, 2024)). The medical treatment costs assumptions include information on how often people go to physician offices and get hospitalized, as well as the average cost for each service. For example, of every hospitalized case of Campylobacter that recovered, there were two preceding physician office visits, on average, at a mean cost of $733 per visit. There was also an average of one hospital admission, at a mean cost of $14,059 per hospitalization. Thus, the total average medical cost per non-fatal hospitalized case of campylobacteriosis (illness caused by Campylobacter) is $15,525. All dollar amounts in this worksheet are expressed in 2023 U.S. dollars (base year) and can be adjusted over time by adjusting for inflation (or deflation) as described in the Documentation.
Some people who were hospitalized for campylobacteriosis were employed and missed work due to their hospitalization. ERS assumes that 46 percent of patients hospitalized for campylobacteriosis were employed, lost 12.3 days of work, and missed out on an average of $303 of earning per day of work missed. Therefore, the average case of hospitalized campylobacteriosis resulted in lost earnings of $1,719 (.46 x 12.3 x $303). Note that there is a rounding error here, which may lead to slight discrepancies in the final value. More detailed documentation is provided in Hoffmann et. al. (2025).
Below the estimates for productivity loss are assumptions about the value of reducing the risk of illness by enough to prevent one death in the U.S. population in a typical year. The value of this reduced risk of mortality is an aggregate of individuals’ willingness to pay for the reduction in risk and is referred to as the VSL. In 2023 dollars, the mean VSL for Campylobacter is $13,070,149, though this figure reflects a calculated mean that incorporates statistical uncertainty, which can lead to slight discrepancies when compared to the fixed baseline VSL value of $13,459,859 from the EPA (2024). A more in-depth explanation of the VSL estimates is provided in the ERS report:
Making Sense of Recent Cost-of-Foodborne-Illness Estimates
The low, mean, and high cost estimates worksheets calculate the specific estimated costs for the low, mean, and high estimated case counts, using the assumptions in the assumptions worksheet. All differences in the estimated costs in low, mean, and high worksheets are driven by differences in the case estimates, as estimated by Scallan et. al. (2011). It is also possible to vary assumptions regarding the VSL (as described in the Documentation), although this sensitivity analysis is not included in the low, mean, and high estimates.
To understand how total cost of illness is calculated, use the Campylobacter mean cost of illness estimates worksheet as an illustration. In a typical year, an average of 8,387 hospitalized cases of foodborne campylobacteriosis recover. In this example, the total medical cost of physician visits is determined by multiplying the 8,387 cases of patients who recovered after hospitalization by the average number of visits per case and the average cost per visit, resulting in $12.3 million. A similar calculation is performed for hospitalizations, where the average number of admissions per case is multiplied by the total number of cases, and the average cost per admission, resulting in $117.9 million. The sum of those two costs yields the total medical cost of $130.2 million. This cost is combined with the productivity loss cost, which is calculated in the same manner using the per-case productivity loss assumption multiplied by the cases, resulting in $14.4 million. The sum of the total medical costs and the productivity loss gives the total costs by outcome among hospitalized cases with recovery, which is $144.6 million from Campylobacter infections in the United States in a typical year.
Costs for cases of foodborne campylobacteriosis that did not receive medical care averaged $72.4 million in a typical year; and costs for cases that sought medical care (physician visits) but were not hospitalized averaged $174.5 million. Hospitalized cases that recovered cost $144.6 million. Individuals would be willing to pay $994.5 million to prevent the mean number of deaths expected from foodborne campylobacteriosis acquired in the United States in a typical year. Additionally, chronic sequelae cases cost $26.9 million from ReA, $9.7 billion from IBS, and $204.9 million from GBS. The total cost of Campylobacter cases is the sum of the total cost of each mutually exclusive health outcome (no physician visit, physician visits only, hospitalized and recovered, hospitalized and died, and chronic cases), resulting in a total cost of $11.3 billion (see column B: totals for acute, chronic, and all illnesses [acute + chronic]).
Resources
Hoffmann, S., White, A.E., McQueen, R.B., Ahn, J.W., Gunn-Sandell, L.B. & Scallan Walter, E.J. (2025). Economic burden of foodborne illnesses acquired in the United States. Foodborne Pathogens and Disease, 22(1), p.4‒14.
Scallan, E., Hoekstra, R. M., Angulo, F. J., Tauxe, R. V., Widdowson, M. A., Roy, S. L., ... & Griffin, P. M. (2011). Foodborne illness acquired in the United States—major pathogens. Emerging Infectious Diseases, 17(1), 7.
U.S. Environmental Protection Agency (EPA). (2024). Guidelines for preparing economic analyses (3rd edition) (Report number EPA-240-R-24-001). Washington, DC.