Travelers’ diarrhea (TD) is a common disease among travelers to developing countries. Although usually self‐limiting, it can disrupt vacations and business trips and cause substantial economic and medical costs. There is abundant information on the epidemiology of TD but only little information on its economic impact. This review provides an overview of the relevant studies and available data to address the various economic aspects of TD and makes an attempt to estimate the costs attributable to TD.

The number of international travelers is steadily increasing. The United Nations World Tourism Organization (UNWTO) estimates the number of international tourist arrivals to exceed 800 million in 2005.1 This is an increase of nearly 50% from 1995. UNWTO’s Tourism 2020 Vision forecasts that international arrivals are expected to reach nearly 1.6 billion by the year 2020.1

Of these travelers, an estimated 80 million people travel from industrialized countries to developing countries, some 35.2 million coming from North America (31.7 million from the United States), 25 million from Europe, 11.4 million from Japan, and 3.3 million from Australia/New Zealand (Figure 1).2,3

Figure 1

Travelers from industrialized areas to developing areas 1999 (WTO). WTO = World Tourism Organization.

Figure 1

Travelers from industrialized areas to developing areas 1999 (WTO). WTO = World Tourism Organization.

Among travel‐related diseases, TD is the most frequent illness for travelers originating in industrialized countries visiting developing countries.4 Classical TD is defined as three or more unformed stools per 24 hours starting during or shortly after a period of foreign travel, with at least one accompanying symptom, such as fecal urgency, abdominal cramps, nausea, vomiting, fever.5 The attack rate of TD occurrence in high‐risk regions averages 30% to 50%.5–10 Thus, approximately 24 to 40 million people worldwide are affected by TD, including 7.5 to 12.5 million from Europe and 9.5 to 15.9 million from the United States.

Although usually a self‐limiting disease, TD can cause substantial disruption by interfering with travel itineraries, business opportunities, and tourist industry revenues. Furthermore, TD can cause significant medical costs and productivity losses if the disease persists when travelers return home. The purposes of this study were to investigate the economic aspects and, as far as possible, to estimate the costs attributable to TD.

Methods

A systematic literature search was conducted using Internet‐accessible databases MEDLINE and Google to identify relevant articles about epidemiologic, economic, healthcare, and tourism data of TD and infectious intestinal diseases. The search period was from November 2006 to January 2007. Keywords searched were “traveler’s diarrhea,”“traveller’s diarrhoea,”“infectious intestinal diseases,”“costs,”“economic,”“health care expenditures,”“economic burden,”“pretravel health advice,”“fees,”“tourism,”“world tourism organization,”“Reisediarrhoe” (TD), “Gesundheitsausgaben” (healthcare expenditures), or any combination of these.

Additionally, the reference lists of the relevant articles were scanned to identify studies and data not revealed by the initial search.

If not otherwise stated, collected cost data were recalculated for 2003 prices using the consumer price index 11 and different currencies were converted using 2003 exchange rates 12 to allow comparison between publications from various publication years. Cost analyses are evaluated from a societal perspective, regardless of who incurs the cost or receives the benefit. Results are presented in a timelined format.

Results

The travel process can be divided into three phases: a pretravel, a travel, and a post‐travel. Various TD‐associated costs can occur during each of these three phases.

Timeline

  1. Pretravel“ 1a. Costs for pretravel health advice“ 1b. Costs for self‐carried medication.

  2. During travel“ 2a. Loss of revenue for tourism countries due to incapacitation“ 2b. Costs for medical care and hospitalizations abroad“ 2c. Other costs (loss of business opportunities, etc.).

  3. Post‐travel“ 3a. Healthcare costs due to ill‐returned travelers who seek medical help at home“ 3b. Lost productivity costs due to workdays lost caused by ill‐returned travelers.

Pretravel

The two most relevant cost factors attributable to TD before traveling are fees for pretravel health advice and costs for self‐carried antidiarrheal medications.

Costs for pretravel health advice

Pretravel health advice can help travelers taking prophylactic measures and thus reduce the risk of getting ill while abroad.

To calculate the costs for pretravel health advice, the number of travelers who seek pretravel health advice must be known in addition to the average cost for a consultation at a travel clinic or a primary care provider.

Studies show that travelers to high‐risk destinations seek pretravel health advice more often than travelers to low‐risk destinations.13,14 According to several surveys (Table 1), more than 50% of travelers to developing countries sought pretravel health advice and around 50% sought pretravel health advice with a physician. The sources include not only primary care provider, travel medicine specialist, company doctors, pharmacist, and travel agency, but also family, friends, Internet, and booklets. Because many travelers consulted more than one source, it was not always possible to extract from the survey data how many actually consulted a doctor.

Table 1

Travelers to developing countries who sought pretravel health advice

Survey Travelers sought pretravel health advice (%)/with a physician (%) n Year of publication 
GeoSentinel Surveillance: ill travelers returning from developing countries 15 55/n/a 17,353 2006 
Stockholm Airport Survey 16 59/53.1 957 2006 
Zurich Airport Survey 17 58.1/58.1 946 2005 
Cuzco Airport Survey 18 61.5/61.5 5,988 2005 
European Airport Survey 19 52.1/48.3 5,067 2004 
Johannesburg Airport Survey 20 86/41.3 419 2004 
NY JFK Airport Survey 21 36/29.5 404 2004 
Australasia Airport Survey 22 32/32 2,101 2004 
Scottish Retrospective Study in General Practice 14 56.8/n/a 81 1997 
Scottish Retrospective Study in General Practice 13 68/n/a 71 1994 
Average 56.5/50.4  
Survey Travelers sought pretravel health advice (%)/with a physician (%) n Year of publication 
GeoSentinel Surveillance: ill travelers returning from developing countries 15 55/n/a 17,353 2006 
Stockholm Airport Survey 16 59/53.1 957 2006 
Zurich Airport Survey 17 58.1/58.1 946 2005 
Cuzco Airport Survey 18 61.5/61.5 5,988 2005 
European Airport Survey 19 52.1/48.3 5,067 2004 
Johannesburg Airport Survey 20 86/41.3 419 2004 
NY JFK Airport Survey 21 36/29.5 404 2004 
Australasia Airport Survey 22 32/32 2,101 2004 
Scottish Retrospective Study in General Practice 14 56.8/n/a 81 1997 
Scottish Retrospective Study in General Practice 13 68/n/a 71 1994 
Average 56.5/50.4  

n/a = not available.

Of the 32 million travelers from the United States, around 16 million would consult a medical provider before traveling.3 Of the 25 million travelers from the European Union (EU), around 12.5 million would consult a medical provider before traveling.3

The consultation fee with a primary care provider or travel clinic varies greatly depending on location, specialization, and whether a doctor or other medical professionals advise the travelers to be. In the United States, consultation fees vary between $US20 at less specialized clinics and up to $US90 at more specialized travel clinics.23–28 For calculation purpose, a rough estimate of $US55 would be suggested.

For the EU, another approach was used because it is more difficult to obtain the consultation fees in all the different countries. The average healthcare unit cost for general practitioners and for outpatient visits was used from an economic study of cardiovascular diseases in the enlarged EU.29 Using these numbers, the population‐adjusted average health‐care unit cost would be approximately €40 (rounded from €38.8).

Using the above‐mentioned data would result an estimated $US880 million and €500 million for pretravel health advice in the United States and EU, respectively (Table 2).

Table 2

Cost estimates for pretravel health advice

Region Consultation fee Number of consultations (million) Total costs (million) 
United States USD 55 16 USD 880 
European Union EUR 40 12.5 EUR 500 
Region Consultation fee Number of consultations (million) Total costs (million) 
United States USD 55 16 USD 880 
European Union EUR 40 12.5 EUR 500 

However, these costs are not fully attributable to TD because there are many other travel‐related diseases. Furthermore, it should not be regarded as costs but rather as an investment for prevention because pretravel health advice can reduce the risk for travel‐associated diseases, although the effect of pretravel health advice on the incidence of TD remains unsatisfactory.30

Costs for self‐carried medication

Similar to the pretravel health service costs, the costs for antidiarrheal medication usually have to be burdened by the travelers themselves.

Figures for the percentage of travelers carrying medication can be found in a study by Reed and colleagues, which shows that 73% of those who sought pretravel health advice carried medication compared to 46% of those who had not received pretravel advice, and of those equipped with medication, 56% carried antidiarrheal medication.13 This would result in 33% of all travelers carrying antidiarrheal medication or 26.4 million of the worldwide 80 million travelers to developing countries. As mentioned below, drug prices vary greatly even within one country; therefore, it makes only limited sense to calculate the total cost for self‐carried antidiarrheal medication. Assuming a price of $US5 for one pack of loperamide 2 mg 18 caps, 31 self‐carried antidiarrheal medication would cost travelers more than $US130 million each year.

Oral antibiotics are usually prescription drugs; therefore, probably fewer travelers would carry oral antibiotics with them compared to antidiarrheal medication. However, assuming that all travelers who carry antidiarrheal medication also carry oral antibiotics (eg, ciprofloxacin) and assuming a price of $US5.5 for one tablet of ciprofloxacin, 31 an empirical self‐therapy with 750 mg as a single dose would cost travelers more than $US145 million each year.

During travel

Loss of revenue for tourism countries due to incapacitation

For many developing countries, tourism is an important pillar of their economy. International tourism generated more than $US2 billion a day in 2005, and worldwide international tourism receipts are estimated at $US680 billion in 2005.1

Although TD is usually a self‐limiting disease, it can cause substantial disruption by interfering with travel itineraries. With its high attack rate in developing countries, it can cause a substantial loss of revenue for tourism countries.

In “Tourism highlights” published by the UNWTO, the figures for “international tourist arrivals” and “international tourism receipts” broken down to travel regions can be obtained.1 From these data, we can estimate an average “receipts per arrival” for developing regions of $US720 or €640, which does not include receipts from international passenger transport (Table 3). (Note: Data refer to the number of arrivals and not to the number of persons. The same person who makes several trips to a given country during a given period will be counted as a new arrival each time, as well as a person who travels through several countries on one trip is counted as a new arrival each time.) 1

Table 3

International tourism receipts and tourist arrivals for developing regions

2003/regions International tourism receipts (in billions of USD) International tourism receipts (in billions of EUR) International tourist arrivals (in million) 
Southeast Asia 24.3 21.5 36.2 
South Asia 5.8 5.1 6.4 
Caribbean 17.8 15.8 17 
Central America 3.3 4.9 
South America 8.7 7.7 13.7 
Sub‐Saharan Africa 10.5 9.2 19.7 
Total 70.4 62.3 97.9 
Average receipts per arrival (not in billions) USD 720 EUR 640  
2003/regions International tourism receipts (in billions of USD) International tourism receipts (in billions of EUR) International tourist arrivals (in million) 
Southeast Asia 24.3 21.5 36.2 
South Asia 5.8 5.1 6.4 
Caribbean 17.8 15.8 17 
Central America 3.3 4.9 
South America 8.7 7.7 13.7 
Sub‐Saharan Africa 10.5 9.2 19.7 
Total 70.4 62.3 97.9 
Average receipts per arrival (not in billions) USD 720 EUR 640  

If this figure can be interpreted as the amount of money a tourist would spend per arrival at a developing country, then the missing variable for the equation would be only the average length of stay per arrival.

Table 4 shows the median duration of stay in three surveys for travelers to developing countries.

Table 4

Median duration of stay

Survey Median duration of stay (d) 
Reinthaler 32 
Steffen and colleagues 2 7 and 14 
Hill 33 19 
Average 11.75 
Survey Median duration of stay (d) 
Reinthaler 32 
Steffen and colleagues 2 7 and 14 
Hill 33 19 
Average 11.75 

Assuming an average of 11.75 days of stay per arrival, the average spending per day would be approximately $US61. With potentially 24 to 40 million travelers affected by TD in developing countries and about 20% of them confined to bed for a day, 30 one incapacitation day would result in $US290 to $US490 million of lost revenue. Depending on travel destination, the duration of incapacitation can vary significantly. The mean duration of incapacitation varied between 12 hours in Jamaica and 3.5 days in West Africa.34,35 It should be noted that already half a day of incapacitation could ruin the travel itinerary for the whole day.

However, hotel costs and other prepaid service packages are fixed costs for travelers and generally cannot be refunded regardless of possible incapacitations.

Costs for medical care and hospitalizations abroad

Costs for medical help abroad might be another aspect to examine. Between 7 and 18% of patients with TD seek professional help abroad from doctors, nurses, or pharmacists, and between 0.03 and 0.2% of patients are hospitalized abroad.9 In absolute figures, 5.6 to 14.4 million patients would seek medial help abroad and between 24,000 and 160,000 hospitalizations would be required. Steffen and colleagues estimated the total cost for TD, including medication, medical treatment, and missed activities, to $US116.5 per patient per stay in Jamaica (1996/1997).34 Although this figure cannot be generalized for all travel destinations, it would implicate costs of more than $US1 billion attributable to TD for medication, medical treatment, and missed activities abroad.

Other costs

Another cost aspect attributable to TD is missed business opportunities. Business travel accounted for some 16% of all travel activities in 2005.1 However, it is difficult, yet impossible, to calculate lost business revenues on a global perspective.

Post‐travel

Cost factors after traveling are healthcare costs due to ill‐returned travelers who seek medical help at home and lost productivity costs due to workdays lost caused by ill‐returned travelers.

HealthCare costs due to ill‐returned travelers who seek medical help at home

TD is usually a self‐limiting disease, so it might seem that returning travelers would not or only rarely seek medical help at home. Several studies demonstrated, however, that a not negligible part of the ill‐returning travelers seek medical help at home because of diarrhea.

In the GeoSentinel Network Study, data for 17,353 ill‐returned travelers who went to 1 of the 30 GeoSentinel Sites, which are specialized travel or tropical medicine clinics, were evaluated.15 Of these, 5,813 patients presented with acute or chronic diarrhea, which is 33% of all cases.

Hill conducted a survey that demonstrated that 26% of all travelers to the developing world reported an illness on return, 13% reported diarrhea, and 46% of those who were ill sought medical care at home.33 In a different study, Reed and colleagues showed that 48% of ill travelers saw their general practitioner at home, a comparable percentage.13 If we calculate with these numbers, approximately 4% of all travelers seek medical care at home because of diarrhea.

Expressed in absolute figures, 10.4 million travelers returning from developing countries worldwide would complain of diarrhea, including 4.12 million in the United States and 3.25 million in the EU, and of these 1.27 million in the United States and 1 million in the EU would consult a physician at home because of diarrhea.

One possible reason for why so many travelers have to seek medical help at home, despite the fact that TD is a self‐limiting disease, is that part of these TD cases are chronic or parasitic in nature. In contrast to this, community‐acquired diarrhea at home is usually acute in nature.

The data in the GeoSentinel Network Study show that 57% of all diarrhea cases are either chronic or parasitic.15 In this study, diagnosis such as ulcerative colitis, Crohn’s disease, chronic unknown diarrhea (postinfectious), irritable bowel syndrome (IBS) (postinfectious), lactose intolerance, malabsorption, and tropical sprue was counted as chronic diarrhea.

Several other studies showed that chronic or parasitic diarrhea is more common than one might think: two studies reported that after a bout of enteric infection, between 7 and 17% of individuals with a normal previous bowel habit developed persistent bowel symptoms, compatible with IBS.36,37 Reinthaler and colleagues showed that more than 20% of all TD cases are persistent (15–30 d) and 2.4% of all TD cases last more than 1 month.32

Chronic and parasitic diarrhea usually cause higher medical costs because more consultations, more expensive laboratory investigations, and drugs are needed.

The next problem is to figure out the TD‐associated medical costs. Basically, there are two approaches: the bottom‐up and the top‐down approach.

With the bottom‐up approach, it is necessary to figure out the physician consultation cost, as well as the laboratory diagnostic and treatment cost for an average TD case. This is a difficult task because there is an ample scope on what laboratory diagnostics should be done and when a treatment might be reasonable. Even if we assume a standard TD case, there is still the problem that the laboratory diagnostic and drug prices vary greatly within one country, not to mention within the many countries in Europe. To give an example: in Switzerland, the antidiarrheal drug loperamide 2 mg 20 capsules costs as the generic product “Loperamid Helvepharm” CHF 9.85; the original product “Imodium” costs CHF 14.85.38 This is a price difference of more than 50%.

The problem of the top‐down approach is to find the total medical expenditures for TD. There is probably no such statistical data, but instead, we can use data from national health expenditures broken down to major disease groups. TD is usually of infectious origin and can be classified as intestinal infectious diseases (IID) (ICD‐10 I A00‐09). Such data are, however, difficult to find, and in most publications, the medical expenditures are only broken down to IA00‐B99, certain infectious and parasitic diseases. Only for Germany 39 and the Netherlands, 40 medical expenditures for IID could be found in publications. For the United States, there are estimated figures for IID from Garthright and colleagues 41 (Table 5).

Table 5

Medical expenditures for ICD‐10 I A00‐B99 (certain infectious and parasitic diseases) and I A00‐09 (intestinal infectious diseases)

Country ICD‐10 (certain infectious and parasitic diseases) (in millions) ICD‐10 (intestinal infectious diseases) (in millions) 
Germany (2004) 39 EUR 3,886 USD 5,114* EUR 826 USD 1,087* 
France (1998) 42 EUR 2,275 USD 2,790* — — 
United States (1995/1985) 43 USD 17,040 USD 23,224* USD 1,250 41 USD 2,430* 
Canada (1998) 42 CND 909 USD 742* — — 
The Netherlands (2003) 40 EUR 1,067 USD 1,283* EUR 42.9 USD 51.6* 
Australia (1993) 42 AUD 849 USD 829* — — 
Spain (1993) 42 EUR 828 USD 1,408* — — 
Japan (1999) 42 JPY 708,500 USD 6,045* — — 
Country ICD‐10 (certain infectious and parasitic diseases) (in millions) ICD‐10 (intestinal infectious diseases) (in millions) 
Germany (2004) 39 EUR 3,886 USD 5,114* EUR 826 USD 1,087* 
France (1998) 42 EUR 2,275 USD 2,790* — — 
United States (1995/1985) 43 USD 17,040 USD 23,224* USD 1,250 41 USD 2,430* 
Canada (1998) 42 CND 909 USD 742* — — 
The Netherlands (2003) 40 EUR 1,067 USD 1,283* EUR 42.9 USD 51.6* 
Australia (1993) 42 AUD 849 USD 829* — — 
Spain (1993) 42 EUR 828 USD 1,408* — — 
Japan (1999) 42 JPY 708,500 USD 6,045* — — 
*

Inflation adjusted for 2007 and converted to USD.44,45

If the incidence for IID and the physician consultation rate are known, it is possible to calculate the average cost for one TD case. According to a study by Wheeler and colleagues, IID occurs in one in five people each year, of whom one in six present to a general practitioner.46 This results in a physician consultation rate of 1 in 30 (0.033). Garthright and colleagues used in their study a comparable physician consultation rate of 0.036.41 With a midyear population of 82.5 million in Germany and 16.2 million in the Netherlands, 47 one IID case would result in medical cost of €278 in Germany and €74 in the Netherlands, a relative big difference.

Garthright and colleagues calculated in their study with a medical cost per case of $US87 for 1985.41 Inflation adjusted for the year 2003, this would be $US149 or €132.11

Assuming that an acute TD case would cause medical cost of $US149 and €132, respectively, for the United States and EU, and a chronic or a parasitic case would cause at least the twofold because more consultations, more in‐depth diagnostic, and more expensive medications are needed, then we can estimate the total medical cost to $US299 million for the United States and €207 million for the EU (Tables 6 and 7).

Table 6

Cost estimates for medical expenses and value of lost productivity from TD for the United States

United States Number of cases (in millions) Medical cost per case (in USD) Medical cost (in millions of USD) Total medical cost (in millions of USD) Daily earnings (in USD) Lost productivity (in millions of USD) Total lost productivity (in millions of USD) 
Total reporting diarrhea at home 4.12  
Acute with consultation 0.546 149 81.35 299 135 73.7 654 
Chronic/parasitic with consultation 0.724 298 217.75  270 195.5  
Without consultation 2.85 — — — 135 384.75  
United States Number of cases (in millions) Medical cost per case (in USD) Medical cost (in millions of USD) Total medical cost (in millions of USD) Daily earnings (in USD) Lost productivity (in millions of USD) Total lost productivity (in millions of USD) 
Total reporting diarrhea at home 4.12  
Acute with consultation 0.546 149 81.35 299 135 73.7 654 
Chronic/parasitic with consultation 0.724 298 217.75  270 195.5  
Without consultation 2.85 — — — 135 384.75  
Table 7

Cost estimates for medical expenses and value of lost productivity from TD for the EU

EU Number of cases (in millions) Medical cost per case (in EUR) Medical cost (in millions of EUR) Total medical cost (in millions of EUR) Daily earnings (in EUR) Lost productivity (in millions of EUR) Total lost productivity (in millions of EUR) 
Total reporting diarrhea at home 3.25 — —  
Acute with consultation 0.43 132 56.76 207 106 31.8 448 
Chronic/parasitic with consultation 0.57 264 150.48  312 177.8  
Without consultation 2.25 — — — 106 238.5  
EU Number of cases (in millions) Medical cost per case (in EUR) Medical cost (in millions of EUR) Total medical cost (in millions of EUR) Daily earnings (in EUR) Lost productivity (in millions of EUR) Total lost productivity (in millions of EUR) 
Total reporting diarrhea at home 3.25 — —  
Acute with consultation 0.43 132 56.76 207 106 31.8 448 
Chronic/parasitic with consultation 0.57 264 150.48  312 177.8  
Without consultation 2.25 — — — 106 238.5  

EU = European Union.

Lost productivity costs due to workdays lost caused by ill‐returned travelers

Mortality‐associated loss of productivity is negligible because there are hardly any fatal TD cases. Concerning morbidity‐associated loss of productivity, only assumptions can be made.

We assume that one acute TD case with and without physician consultation would result in 1 workday lost and one chronic or parasitic case would result in at least 2 workdays lost.

Daily earnings for the EU (€106, population adjusted) can be obtained from the above‐mentioned economic study of cardiovascular diseases in the enlarged EU.29

Daily earnings for the United States can be estimated by the annual personal income per capita, calculated with 233 workdays (248 workdays for 2003 minus 15‐d vacation).48,49 This would result in daily earnings of $US135.

Calculated with these assumptions, we estimate a lost productivity cost of $US654 million and €448 million (Tables 6 and 7).

Discussion

About 50% of travelers to developing countries seek pretravel health advice with a medical professional. We estimate the total costs for pretravel health advice to be around $US880 million in the United States and around €500 million in the EU.

Because many US travelers visit destinations like Mexico or the Caribbean (around 25 million) where the percentage of travelers seeking pretravel health advice is probably much lower, around 14%, 13 the actual pretravel physician visits are more likely to be near 7 million and the costs for pretravel health advice should be around $US385 million. However, because the “Airport Surveys” do not specifically exclude travelers to Mexico and the Caribbean, it is questionable if it is appropriate to drop these travelers in the calculations.

We believe that the actual costs for pretravel health advice lies between these two figures.

These costs for pretravel health advice should not be regarded as costs but rather as an investment for prevention because pretravel health advice can reduce the risk for travel‐associated diseases, although the effect of pretravel health advice on the incidence of TD remains unsatisfactory. Furthermore, it should be noted that the fees for pretravel health advice usually have to be burdened by the individual travelers themselves and not by the society as a whole.

Little information was found concerning self‐carried antidiarrheal medication. Combining the available data shows that 33% of travelers carry antidiarrheal medication. Because drug prices vary greatly even within one country, a conclusive estimation of these costs is difficult.

International tourism is an important economic pillar for many developing countries. A high attack rate of TD in a tourism country can cause substantial losses in tourism revenues.

We estimate that 1 day of incapacitation due to TD would result in up to $US490 million of missed tourism revenue for developing countries. It should be noted that the airfare is already excluded from the calculation. However, there are other nonrefundable/prepaid costs, like hotel costs, which would not be lost by incapacitation. Unfortunately, we could not find any data on what percentage of the expenditures of the travelers is spent on prepaid costs.

Assuming that half of the $US60 per day would be spent on lodging, which is not little for developing countries, this would still result in up to $US245 million of missed tourism revenue for 1 day of incapacitation. However, data from the US Office of Travel and Tourism Industries suggest that probably less travelers use prepaid packages than one might think, eg, only 13% of travelers use prepaid packages and only 55% use prebooked lodging.50

Another source of revenue lost may come from travelers who do not travel to high‐risk regions because of fear of TD; however, a survey showed that very few travelers answered that they would not come back for health reasons (between 0.1 and 1.4%).2

In consideration of these figures, an enhancement of the sanitary infrastructure in developing countries with a high attack rate of TD can be a worthwhile investment.

Health‐care costs and productivity losses due to ill‐returning travelers have a direct economic impact on the industrialized countries. We estimate nearly $US300 million in medical costs and more than $US650 million in lost productivity costs for the United States and more than €200 million in medical costs and nearly €450 million in lost productivity costs for the EU. However, these figures compared to the total US healthcare expenditures, which surpassed $US1.7 trillion in 2003, play only a minor role.51

Some epidemiologic data on travelers’ situations before and during travel, such as the share of people who seek pretravel health advice, attack rate, or duration of stay, are sufficiently available, but it lacks data on the health situation after travel, such as how many returning travelers are ill due to TD, what percentage need medical care at home, and how long they are absent from work. Accurate data on unit costs and total healthcare costs broken down to specific disease groups are also not sufficiently available. Also, more detailed information on tourism and in particular tourism spending is desirable. For these reasons, many assumptions and extrapolations have to be made that can potentially lead to flawed estimates. To conduct more accurate cost‐of‐illness studies in the future, more detailed information about epidemiology and more accurate information about resource use and unit costs is imperative.

This review is by no means exhaustive but serves as an attempt to estimate the economic burden of TD and to provide data for further, more extensive investigations.

Declaration of interests

R. S. has accepted fees for speaking, organizing and chairing education, consulting, and/or serving on advisory boards, also reimbursement for attending meetings and funds for research from Astral, Berna Biotech/Crucell, Baxter, Chiron Behring (now Novartis Vaccine), GlaxoSmithKline, Novartis, Optimer, Salix Pharmaceuticals, and/or Sanofi Pasteur MSD. The other authors state that they have no conflicts of interest.

References

1
World Tourism Organization
.
Tourism highlights
.
2006
. Available at: http://www.unwto.org/facts/menu.html. (Accessed 2007 Jan 6)
2
Steffen
R
Tornieporth
N
Clemens
SA
, et al.
Epidemiology of travelers’ diarrhea: details of a global survey
.
J Travel Med
 
2004
;
11
:
231
237
.
3
Leggat
PA
.
Lecture notes
.
2005
. Available at: http://www.pitt.edu/~super1/lecture/lec19341/008.htm. (Accessed 2007 Jan 6)
4
Steffen
R
DeBernardis
C
Banos
A
.
Travel epidemiology—a global perspective
.
Int J Antimicrob Agents
 
2003
;
21
:
89
95
.
5
Von Sonnenburg
F
Tornieporth
N
Waiyaki
P
, et al.
Risk and aetiology of diarrhea at various tourist destinations
.
Lancet
 
2000
;
356
:
133
134
.
6
Kean
BH
Waters
SR
.
The diarrhea of travelers II. Drug prophylaxis in Mexico
.
N Engl J Med
 
1959
;
261
:
71
74
.
7
DuPont
HL
Haynes
GA
Pickering
LK
, et al.
Diarrhea of travelers to Mexico: relative susceptibility of United States and Latin American students attending a Mexican university
.
Am J Epidemiol
 
1977
;
105
:
37
41
.
8
Ericsson
CD
DuPont
HL
Mathewson
JJ
III
.
Epidemiologic observations on diarrhea developing in U.S. and Mexican students living in Guadalajara, Mexico
.
J Travel Med
 
1995
;
2
:
6
10
.
9
Steffen
R
Van der Linde
F
Gyr
K
Schar
M
.
Epidemiology of diarrhea in travelers
.
J Am Med Assoc
 
1983
;
249
:
1176
1180
.
10
Steffen
R
.
Epidemiologic studies of travelers’ diarrhea, severe gastrointestinal infections and cholera
.
Rev Infect Dis
 
1986
;
8
(
Suppl 2
):
S122
S130
.
11
.
Six Ways to Compute the Relative Value of a U.S. Dollar Amount, 1790–2006
.
2007
. Available at: http://www.measuringworth.com/uscompare/. (Accessed 2007 Jan 6)
12
European Central Bank
.
Exchange rate
.
2007
. Available at: http://sdw.ecb.int/browse.do. (Accessed 2007 Jan 6)
13
Reed
JM
McIntosh
IB
Powers
K
.
Travel illness and the family practitioner: a retrospective assessment of travel‐induced illness in general practice and the effect of a travel illness clinic
.
J Travel Med
 
1994
;
1
:
192
198
.
14
McIntosh
IB
Reed
JM
Power
KG
.
Travellers’ diarrhoea and the effect of pre‐travel health advice in general practice
.
Br J Gen Pract
 
1997
;
47
:
71
75
.
15
Freedman
DO
Weld
LH
Kozarsky
PE
, et al;
GeoSentinel Surveillance Network. Spectrum of disease and relation to place of exposure among ill returned travelers
.
N Engl J Med
 
2006
;
354
:
119
130
.
16
Dahlgren
AL
DeRoo
L
Steffen
R
.
Prevention of travel‐related infectious diseases: knowledge, practices and attitudes of Swedish travellers
.
Scand J Infect Dis
 
2006
;
38
:
1074
1080
.
17
Gisler
S
Steffen
R
Mutsch
M
.
Knowledge, attitudes and practices among travellers to tropical and subtropical countries
.
Schweiz Rundsch Med Prax
 
2005
;
94
:
967
974
.
18
Cabada
MM
Maldonado
F
Quispe
W
, et al.
Pretravel health advice among international travelers visiting Cuzco
,
Peru. J Travel Med
 
2005
;
12
:
61
65
.
19
Gisler
S
Steffen
R
Gargalianos
P
, et al.
Knowledge, attitudes and practices in travel‐related infectious diseases: the European airport survey
.
J Travel Med
 
2004
;
11
:
3
8
.
20
Toovey
S
Jamieson
A
Holloway
M
.
Travelers’ knowledge, attitudes and practices on the prevention of infectious diseases: results from a study at Johannesburg International Airport
.
J Travel Med
 
2004
;
11
:
16
22
.
21
Hamer
DH
Connor
BA
.
Travel health knowledge, attitudes and practices among United States travelers
.
J Travel Med
 
2004
;
11
:
23
26
.
22
Wilder‐Smith
A
Khairullah
NS
Song
JH
, et al.
Travel health knowledge, attitudes and practices among Australasian travelers
.
J Travel Med
 
2004
;
11
:
9
15
.
23
San Francisco Bay Guardian Online
.
Superlist no. 812. Check before you trek
.
2005
. Available at: http://www.sfbg.com/39/26/cover_super_travel_clinics.html. (Accessed 2007 Jan 20)
24
NC State University
,
Student Health Services
.
Fee for the Travel Clinic
.
2006
. Available at: http://www.ncsu.edu/student_health/Travel/travel.html. (Accessed 2007 Jan 20)
25
Odyssey Travel
and
Tropical Medicine Clinic
.
Clinic Fees
.
2007
. Available at: http://odysseytravelclinic.com/default.asp?V_DOC_ID=834. (Accessed 2007 Jan 20)
26
Kalamazoo College Health Center
.
Travel Clinic
.
Travel Clinic Fee Schedule
.
2006
. http://www.kzoo.edu/healthcenter/about_us/travel.html. (Accessed 2007 Jan 20)
27
Carle Clinic Association
,
Travel Clinic
.
Office Visit Fees
.
2006
. Available at: http://www.carle.com/cca/SpecialServices/travelclinicfees.htm. (Accessed 2007 Jan 20)
28
West Virginia University
,
International Travel Clinic
.
Fee
.
2006
. Available at: http://www.hsc.wvu.edu/shs/services/internationalTravel.asp. (Accessed 2007 Jan 20)
29
Leal
J
Luengo‐Fernandez
R
Gray
A
, et al.
Economic burden of cardiovascular diseases in the enlarged European Union
.
Eur Heart J
 
2006
;
27
:
1610
1619
.
30
Al‐Abri
SS
Beeching
NJ
Nye
FJ
.
Traveller’s diarrhoea
.
Lancet Infect Dis
 
2005
;
5
:
349
360
.
31
.
Search: Ciprofloxacin
.
2007
. Available at: http://www.drugstore.com. (Accessed 2007 Jan 6)
32
Reinthaler
FF
Feierl
G
Stunzner
D
Marth
E
.
Diarrhea in returning Austrian tourists: epidemiology, etiology, and cost‐analyses
.
J Travel Med
 
1998
;
5
:
65
72
.
33
Hill
DR
.
Health problems in a large cohort of Americans traveling to developing countries
.
J Travel Med
 
2000
;
7
:
259
266
.
34
Steffen
R
Collard
F
Tornieporth
N
, et al.
Epidemiology, etiology, and impact of traveler’s diarrhea in Jamaica
.
JAMA
 
1999
;
281
:
811
817
.
35
Bruni
M
Steffen
R
.
Impact of travel‐related health impairments
.
J Travel Med
 
1997
;
4
:
61
64
.
36
Neal
KR
Hebden
J
Spiller
R
.
Prevalence of gastrointestinal symptoms six months after bacterial gastroenteritis and risk factors for development of the irritable bowl syndrome: post survey of patients
.
Br Med J
 
1997
;
314
:
779
782
.
37
Parry
SD
Barton
R
Welfare
MR
.
Prevalence of pre‐existing functional gastrointestinal disorders (FGID) in infectious diarrhoea (ID) subjects compared to a matched community control group
.
Gastroenterology
 
2001
;
120
:
A633
.
38
Documed
.
“imodium” and “Loperamid Helvepharm”
.
2007
. Available at: http://www.documed.ch/. (Accessed 2007 Jan 6)
39
Statistisches Bundesamt
.
Gesundheit—Ausgaben, Krankheitskosten und Personal 2004
.
2005
. Available at: http://www.destatis.de. (Accessed 2007 Jan 6)
40
Department of Public Health—Erasmus University
.
Cost of illness in the Netherlands
.
2006
. Available at: http://www.rivm.nl/kostenvanziekten/site_en/. (Accessed 2007 Jan 6)
41
Garthright
WE
Archer
DL
Kvenberg
JE
.
Estimates of incidence and costs of intestinal infectious diseases in the United States
.
Public Health Rep
 
1988
;
103
:
107
115
.
42
Paris
V
Renaud
T
Sermet
C
.
Des comptes de la sante par pathologie: un prototype pour l’annee 1998
. Dossiers solidarite et sante no.2. Paris, France:
Ministère des Solidarités de la Santé et de la Famille
,
2003
.
43
Hodgson
TA
Cohen
AJ
.
Medical expenditures for major diseases, 1995
.
Health Care Financ Rev
 
1999
;
21
:
119
164
.
44
Economic History Services
.
Exchange Rates Between the United States Dollar and Forty‐one Currencies
.
2007
. Available at: http://eh.net/hmit/exchangerates. (Accessed 2007 Jan 6)
45
Federal Reserve Bank of Cleveland
.
Economic Research & Data. Inflation central. World inflation
.
2007
. Available at: http://www.clevelandfed.org/research/Inflation/World-Inflation/Index.cfm. (Accessed 2007 Jan 6)
46
Wheeler
JG
Sethi
D
Cowden
JM
, et al.
Study of infectious intestinal disease in England: rates in the community, presenting to general practice, and reported to national surveillance. The Infectious Intestinal Disease Study Executive
.
BMJ
 
1999
;
318
:
1046
1050
.
47
World Health Organization
:
Regional Office for Europe
.
2006
.
European health for all database
. Available at: http://www.euro.who.int/hfadb. (Accessed 2007 Jan 6)
48
Bureau of Economic Analysis
,
U.S Department of Commerce
.
United States Per Capita Personal Income
.
2006
. Available at: http://www.bea.gov/bea/regional/reis/default.cfm?catable=CA1-3&section=2. (Accessed 2007 Jan 20)
49
The State of California
,
Division of Construction
.
Working days calendar
.
2007
. Available at: http://www.dot.ca.gov/hq/construc/calendar.html. (Accessed 2007 Jan 20)
50
U.S. Department of Commerce
,
Office of Travel and Tourism Industries
,
2003 Profile of U.S. Resident Traveler Visiting Overseas Destinations Reported From: Survey of International Air Travelers
.
2004
. Available at: http://tinet.ita.doc.gov/view/f-2003-101-001/index.html. (Accessed 2007 Aug 11)
51
Centers for Medicare & Medicaid Services
.
National Health Expenditure data
. NHE Web tables.
2006
. Available at: http://www.cms.hhs.gov/NationalHealthExpendData/. (Accessed 2007 Jan 20)