As the number of United States residents travelling outside their country continues to rise, the predominant choice of high risk destinations places this growing proportion of the population at heightened levels of risk from waterborne disease including travelers’ diarrhea.

•  Over 18 million U.S. residents affected by travelers’ diarrhea abroad

•  More than 7.5 million travelers had to change their itinerary due to to travelers’ diarrhea

•  Nearly 4 million confined to bed by travelers’ diarrhea during foreign travel

•  Almost 188,000 admitted to hospital when abroad due to travelers’ diarrhea

Following an increase from 13% in 1996 to 41% in 2016, more U.S. citizens now hold a passport than ever before, and in 2016 they were used for 80.2 million visits abroad. This record-breaking figure was an 8% increase over 2015, but a breakdown of recently released details from the U.S. Dept. of Commerce’s International Trade Administration suggests that U.S. travelers may be experiencing a disproportionate risk of contracting travelers’ diarrhea (TD) and other waterborne diseases by comparison to those of some other nations citizens.

It may come as little surprise that the quality of drinking water differs widely between international destinations. The U.S. Centers for Disease Control (CDC) advises that, when it comes to the risk of contracting TD, not all countries are equal, and divides the world into three broad categories of risk; low, intermediate, and high.

The U.K., which uses the same categories, has defined low risk as being 7% or less, intermediate as 8% to 20%, and high as greater than 20% (rising to 60%), as shown in the map above.  CDC has defined high risk as being from 30% to 70%.

For U.K. travelers, the percentages traveling in 2016 to intermediate and high risk countries contrasted sharply with the figures for U.S. travelers.

Table 1: Total numbers and percentage of U.K. and U.S. travelers by TD risk zone in 2016.

For UK total travelers in 2016 see Table 2a below. For US total travelers in 2016 see Table 2b below.

For UK total travelers in 2016 see Table 2a below. For US total travelers in 2016 see Table 2b below.

Table 2a: U.K. travelers by destination 2015-16.

Information derived from the ONS UK Residents Visits Abroad online datasets

Information derived from the ONS UK Residents Visits Abroad online datasets

Table 2b: U.S. travelers by destination 2015-16.

Information derived from the U.S. Department of Commerce’s National Travel and Tourism Office online data.

Information derived from the U.S. Department of Commerce’s National Travel and Tourism Office online data. Note that in 2015 the 43 most popular overseas destinations for U.S. outbound travelers were listed.  This figure was reduced to 38 countries when the 2016 figures were made available. This table only includes countries for which figures were provided in both 2015 and 2016.  Countries that appeared in 2015 only included New Zealand (low risk; 295,000 travelers), Russia (intermediate risk; 215,000 (based on 2014 figure)), Ecuador (high risk; based on 2014 figure)), Morocco (high risk; 164,000), and Turkey (high risk; 426,000). While the figures derived from this table are strongly indicative of possible TD occurrence, the actual figure may therefore be higher than described.

Table 1 clearly shows that while nearly four times as many U.K. travelers visited intermediate risk destinations as those who traveled to high risk destinations, this position is almost reversed for U.S. residents, with over half of all journeys being made to high risk destinations.

By far the most significant single factor in the U.S. figures is Mexico, with over 31 million journeys representing more than 77% of the high risk total.  However, U.S. residents’ travel in 2016 also increased in 10 of the 15 other high risk destinations listed.

In terms of the potential numbers of U.S. residents who might have been affected by TD on the basis of where they traveled, Table 3 utilizes a median figure for each of the three risk categories in combination with the numbers of trips recorded in 2015 and 2016.

Table 3: Potential incidence of Travelers’ Diarrhea for U.S. residents traveling abroad in 2015-16.

his table uses median risk percentages based on more conservative U.K. definitions of low, intermediate and high risk areas as described above

This table uses median risk percentages based on more conservative U.K. definitions of low, intermediate and high risk areas as described above

With a little under 19 million cases of TD having potentially afflicted U.S. residents during such as their vacations, visits to friends and family, and business trips in 2016, this equates to nearly one quarter of all travelers having suffered from what, as a minimum, is an unpleasant, discomforting and frequently painful interruption to what should otherwise have been an enjoyable or profitable experience.

For many U.S. travelers the consequences may have been of even greater impact. Table 4 highlights the potential number of travelers affected by TD who may have been confined to bed, who may have had to changed their itinerary, or who may have had to be admitted to hospital during the course of their trip.

Table 3: Potential incidence of Travelers’ Diarrhea and additional consequences for U.S. residents traveling abroad in 2015-16.

These percentages are based on the referenced advice of the TravelHealthPro website.

These percentages are based on the referenced advice of the TravelHealthPro website.

An assessment of the financial impact of TD on U.S. travelers can be harder to quantify. Leaving aside such as the loss of tourist income to host countries when a visitor remains in bed (or even chooses an alternative destination on the basis of a poor sanitary reputation), or the cost to the insurance industry of TD-related policy claims, this condition can also substantially affect the personal financial health of travelers.

Added to the more obvious costs of medication and any medical care or hospitalization that may be required, changes in itineraries can affect both afflicted individuals and also uninfected party members; if a child is unable to participate in that once-in-a-lifetime vacation activity due to incapacitation by TD, the chances are that the rest of the family will be missing out too.  For pre-paid and non-refundable activities where re-scheduling is not an option, the loss of a ‘priceless’ experience is a hard hit.