Economic Aspects of Travelers’ Diarrhea

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 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. 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. 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. Pretravel“ 1a. Costs for pretravel health advice“ 1b. Costs for self‐carried medication. 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.). 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. The two most relevant cost factors attributable to TD before traveling are fees for pretravel health advice and costs for self‐carried antidiarrheal medications. 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. Travelers to developing countries who sought pretravel health advice n/a = not available. Travelers to developing countries who sought pretravel health advice 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). Cost estimates for pretravel health advice Cost estimates for pretravel health advice 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 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. 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 International tourism receipts and tourist arrivals for developing regions International tourism receipts and tourist arrivals for developing regions 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. Median duration of stay Median duration of stay 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 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. 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. 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. 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). Medical expenditures for ICD‐10 I A00‐B99 (certain infectious and parasitic diseases) and I A00‐09 (intestinal infectious diseases) Inflation adjusted for 2007 and converted to USD.44,45 Medical expenditures for ICD‐10 I A00‐B99 (certain infectious and parasitic diseases) and I A00‐09 (intestinal infectious diseases) 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 Inflation adjusted for the year this would be or Assuming that an acute TD case would cause medical cost of and for the United States and EU, and a chronic or a parasitic case would cause at least the because more consultations, more and more expensive are then we can estimate the total medical cost to million for the United States and million for the EU and Cost estimates for medical and of lost productivity from TD for the United States Cost estimates for medical and of lost productivity from TD for the United States Cost estimates for medical and of lost productivity from TD for the EU EU = European Cost estimates for medical and of lost productivity from TD for the EU EU = European loss of productivity is negligible because there are any TD cases. loss of only can be assume that one acute TD case with and physician consultation would result in 1 lost and one chronic or parasitic case would result in at least 2 workdays for the EU population can be from the above‐mentioned economic study of cardiovascular diseases in the enlarged EU.29 for the United States can be estimated by the per calculated with workdays workdays for 2003 This would result in of with these we estimate a lost productivity cost of million and million and 50% of travelers to developing countries seek pretravel health advice with a medical estimate the total costs for pretravel health advice to be around $US880 million in the United States and around €500 million in the Because many travelers destinations or the 25 the percentage of travelers pretravel health advice is probably around the pretravel physician visits are more to be 7 million and the costs for pretravel health advice should be around However, because the not travelers to and the it is if it is to these travelers in the that the costs for pretravel health advice between these two 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 Furthermore, it should be noted that the fees for pretravel health advice usually have to be burdened by the travelers and not by the as a information was found self‐carried antidiarrheal medication. the available data shows that 33% of travelers carry antidiarrheal medication. Because drug prices vary greatly even within one country, a of these costs is 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. 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 is already from the However, there are other costs, hotel costs, which would not be lost by we could not find any data on what percentage of the expenditures of the travelers is on prepaid costs. Assuming that half of the per day would be on which is not little for developing countries, this would still result in up to million of missed tourism revenue for 1 day of However, data from the of and Tourism that probably less travelers use prepaid packages than one might only 13% of travelers use prepaid packages and only use Another of revenue lost from travelers who not travel to high‐risk regions because of of however, a survey showed that travelers that would not for health and In of these figures, an of the in developing countries with a high attack rate of TD can be a costs and productivity losses due to ill‐returning travelers have a economic on the industrialized countries. estimate nearly million in medical costs and more than million in lost productivity costs for the United States and more than million in medical costs and nearly million in lost productivity costs for the However, these figures compared to the total healthcare which in only a data on before and during travel, such as the of people who seek pretravel health advice, attack or duration of are but it data on the health after travel, such as how many returning travelers are ill due to TD, what percentage medical care at home, and how are from data on unit costs and total healthcare costs broken down to disease are also not available. more information on tourism and in tourism spending is For these many and have to be that can potentially to To more studies in the more information about epidemiology and more information about use and unit costs is This review is by no but as an attempt to estimate the economic of TD and to data for more fees for and on also for and for from The other that have no of