Epidemiology of Diarrhea in Travelers by liuqingyan


									Epidemiology                                     of Diarrhea in Travelers
Robert Steffen, MD; Franz                 van    der Linde, MD, MPH; Klaus         Gyr, MD, MPH, TM; Meinrad Sch\l=a"\r,MD,                MPH

       To investigate diarrhea in tourists on a worldwide scale, 16,568                                                       Travelers' Diarrhea
passengers were interviewed during their flights home from 13 destinations
                                                                                                                      The definition of travelers' diarrhea was
in various climatic regions. Significant differences in diarrheal incidence
                                                                                                                   similar to that of Merson et al" or Sack et
were observed between individual destinations and also between hotels in
                                                                                                                   al7 as the occurrence of three or more
the same area. The highest rates exceeded 50%. Younger persons were                                               watery or unformed stools per day or any
more often affected. Sex, travel characteristics, and a record of former                                           number of such stools when accompanied
tropical journeys influenced the incidence to a minor degree. Even in the                                         by fever, abdominal cramps, or vomiting.
tropics, diarrhea usually takes a short (average, 3.6 days) and mild (average                                     Loose motions meant one to two watery or
of 4.6 stools per day) course. Prophylactic or therapeutic medication only                                        unformed bowel movements without any
slightly influenced these values. The various regions showed minor differ-                                        of the aforementioned additional symp¬
                                                                                                                  toms. The term diarrhea was used for the
ences in chronology and symptomatology. This is consistent with quantita-
                                                                                                                  sum of travelers' diarrhea plus loose
tive rather than qualitative geographic variations in causative agents. The
                                                                                                                  motions. Blood or mucus in the stool was
traditional nutritional recommendations for prophylaxis seemed to be
unrealistic and usually unsuccessful.
                                                                                                                  investigated but not taken into considera¬
                                                                                                                  tion for definition. Our questioning ex¬
    (JAMA 1983;249:1176-1180)                                                                                     cluded subjects who already suffered from
                                                                                                                  the same degree of diarrhea before the
EACH year, 300 million people under¬                        States and Canada), and July 1980 to                  journey. Multiple attacks in the same
take an international journey.1 Diar¬                       February   1981 for the subtropical regions           person were not assessed separately.
rhea occurs in 0.6 %2 to 94%3 of this                       and the recently inaugurated flights to                   Evaluation of the computer cards was
population. For 12 million persons'"                        Lima, Peru. In the first period of investi¬           done according to the SPSS (Statistical
                                                            gation, the questionnaire consisted of sev¬           Package for the Social Sciences) program
originating in highly industrialized                        en pages. It contained 24 mostly "closed"             7 at the University of Zürich Calculation
countries and traveling to developing                       questions in German only, inquiring about             Center. Analysis of significance is based
lands, this is the most frequent                            personal data (eg, age and sex), the jour¬            on the corrected x2 test. The variability of
health problem during their stay                            ney (eg, dates, destination, lodging, and             arithmetic means is given as ± SE.
abroad.5 Until now, most epidemiolog-                       means of transport), occurrence of diar¬
                                                            rhea (eg, onset, duration, maximal number                              RESULTS
          For editorial comment                             of bowel movements, quality of stools, and                    Population Investigated
                  see     p1193.                            additional symptoms, such as fever, vomit¬               A total of 16,568 travelers were
                                                            ing, abdominal cramps, and admixture of               interviewed for the entire study. This
ic studies     on   travelers' diarrhea have                blood or mucus to the stools), type and
only presented selected populations                         severity of other health problems during              represents 60.2% (range, 18% to
visiting just one destination. The pur¬                     the stay abroad, preventive measures (ie,             100%) of all passengers aboard 162
pose of this investigation is, there¬                       medication, dietary restriction, vaccina¬             charter    flights. Lower   answer    rates
fore, to describe diarrhea in tourists                      tion, and advice given before departure),             on some    flights resulted from inabili¬
                                                            and type of treatment needed. For the                 ty to understand the German text
(who account for over 70% of all
international travelers') to some of                        mostly shorter flights of the second period           (answer rate, 81.7% on bilingual
                                                            of investigation, the number of questions,            questionnaires), children on board,
the most frequently visited holiday
                                                            now formulated in German and French,                  and nighttime or delayed flights.
destinations all        over    the world.                  was reduced to 11 by concentrating on
                                                                                                                  Comparable groups on flights with
                    METHODS                                 personal data, the journey, occurrence of             answer     rates of   greater than 90%
                                                            diarrhea, and relevant preventive mea¬                showed
                Data Collection
                                                            sures taken, but omitting inquiries about
                                                                                                                              no   significant differences
   Data collection was performed during                     other illnesses. The 13 destinations listed           (P=A)     to those with rates less than
consecutive series of charter flights back                  in the Table are self-explanatory or have             50%.
to Switzerland or Germany with the                          been described formerly.5 As comparable                 The population, more than 98% of
assistance of airline cabin crews who                       destinations in the seasons 1975-1976,                European origin, was mostly Swiss,
distributed and collected questionnaires.                   1976-1977, and 1980-1981 had almost iden¬             except for persons whose destination
The periods of investigation were Decem¬                    tical results, they were considered jointly.          was  Mexico, of whom the majority
ber 1975 to March 1977 for most of the                                                                            were   German. The age distribution of
tropical destinations, a part of the Carib¬                            Travel Characteristics
                                                                                                                  tropical visitors is recorded in the
bean, and for the control group, whose                         Travel characteristics   were    defined     as    Table. The median ages by destina¬
destination was North America (United                       follows:                                              tion varied between 29.6 to 42.8 years.
   From the Institute for Social and Preventive
                                                              Beach    Vacation.—Stay   in   only   one   hotel   The proportion of men was 59% in
Medicine, University of Z\l=u"\rich(Drs Steffen and         on a   littoral.
                                                                                                                  the tropics, 46% in the subtropics,
Sch\l=a"\r);the Department of Public Health of the            Multidestination Tour.—Guided or indi¬
Canton of St Gallen (Dr van der Linde); and the             vidual travel with accommodation in sev¬              and 51% in North America. The dura¬
Section of Gastroenterology, Cantonal Hospital,
                                                            eral hotels.                                          tion of stay had medians of 14 days
Basel (Dr Gyr), Switzerland.
   Reprint requests to Institute for Social and Pre-
                                                               Adventure Tour.—Private accommoda¬                 (eg, Tunisia, West Africa, North
ventive Medicine, University of Z\l=u"\rich,Gloriastrasse   tions, camps, cheap hotels, or similar                America) to 27 days (South America).
30, CH-8006 Z\l=u"\rich,Switzerland (Dr Steffen).           places.                                               Six percent of the tourists stayed only

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one    week;   8% spent   more   than 30
                                                                                Incidence of Travelers' Diarrhea (n= 16,568)
days in the tropics.
           Incidence of Diarrhea                                                                                            Travelers' Diarrhea
  The data in the Table show highly                                                                                     Incidence in                Incidence In
significant differences (P<.001) in                                                        No. of           No. of       Entire   Stay        Day    1 to 14 of Stay
the incidence of travelers' diarrhea                        Criteria                      Travelers         Cases        Abroad, %                    Abroad,      %*

according to most destinations and              Tropics (n= 10,555)
                                                     East Africa                           2,646              797           30.1                         27.7
age    groups.   Additionally,     persons           West Africa                             505              197           39.0                         38.2
with   arecord of former stays in the                Sri Lanka/Maldives                    1,371              477           34.8                         32.5
tropics suffered from travelers' diar¬               Thailand                              1,838              409           22.3                         20.9
rhea in 29.1% as compared with                       Far East                              2,470              775           31.4                         25.4
32.3% in those without such experi¬                  Brazil                                1,305              431           33.0                         25.9
ence (P<.001). No significant differ¬                South America                           420              152           36.2                         33.8
ence was detected with respect to sex.          Subtropics (n=4,500)
                                                     Tunisia                                 988              478           48.4                         48.5
The attack rates are slightly influ¬                                                         572                                                         20.4
                                                     Canary Islands                                           114           19.9
enced by the travel characteristics                  Rhodes                                  987              126           12.8                            13.4
(P=.03): adventure-tour participants                 Caribbean                               849              168           19.8                            18.0
are most often affected; beach vaca¬              Mexico                                    1,104             342           31.0                         26.2
tioners are least bothered. Loose               Control group
motions occurred in 3.3% of the trav¬             North America                             1,379              71             5.1                            3.7

elers (range, 0.7% in North America             Exceeding one region                         134               35           26.1                         23.1
                                                Age, yr (tropics)
to 6.0% in Tunisia) without any fur¬                 £19                                     177               53           29.9                         28.7
ther significant differences on the                  20-29                                 2,795             1,023          36.6                         31.8
basis of -the aforementioned criteria,               30-39                                 2,911              905           31.1                         27.7
except for a slightly higher incidence               40-49                                  1,858             501           27.0                         25.0
in male tourists. The season of the                  50-59                                  1.641             464           28.3                         25.9

year showed no influence on the inci¬                60-69                                    974             250           25.7                         21.8
dence of diarrhea. Specification into                2:70                                    232               53           22.8                            18.9

the respective subgroups discloses             'Travelers      staying   13   days   or   less and   patients manifesting diarrhea   after the 14th   day   were   excluded.
that the higher diarrheal rate in the
younger persons cannot be due entire¬
ly to their preference for an adven¬                                                       Fig 1.—Day of       onset of diarrhea.
ture tour, nor to a prolonged duration
of stay, nor to a lower proportion of
former visits to the tropics.
   Within the tropics, Togo, West                                                                           O-O Travelers'       Diarrhea, Tropics
Africa, had the highest incidence of                                                                          -A Loose       Motions, Tropics
diarrhea, with 53% of travelers                                                                             •-•       Travelers' Diarrhea, Subtropics
affected, but the subtropical region of
                                                                                                            9-9 Travelers'            Diarrhea, North America
Monastir, Tunisia, set the overall
record with 57% of travelers affected
(n=782). In the subtropics (except for
Mexico), the vast majority of tourists
were on a beach vacation, interrupted
at most by one-day excursions, thus             v-
allowing a comparison of the inci¬              S
dence of diarrhea by individual
hotels. In 21 Tunisian hotels, each of          I
which accommodated at least 20 per¬
sons in July and August 1980, the
incidence varied from 26% to 89%                0.
(P<.001). These tourists were compa¬
rable in sex and duration of stay, but
the mean age was higher in those at
some of the hotels with a low inci¬
dence. The clients of eight hotels
(four four-star hotels, including one
belonging to a US-based international
chain, and four three-star hotels) had
an incidence of diarrhea of up to 40%,
and guests in an additional seven
hotels (three four-star hotels, one
three-star hotel, and three two-star                                                           Day     of   Stay Abroad
hotels) had an incidence ranging

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                                                                                           between 40% and 60%. In the remain¬
                                                                                           ing six hotels (four three-star and two
                                                                                           two-star, including those belonging to
                                                                                           a French-based international chain),
                                O-O Travelers'               Diarrhea, Tropics
                                                                                           more than 60% of the vacationers
                                A-                Loose Motions, Tropics                   were affected. On Rhodes, Greece,
                                «-•               Travelers' Diarrhea, Subtropics          and on the Canary Islands, Spain, the
                                                                                           incidence of diarrhea by hotel fluc¬
                                9.9 Travelers'              Diarrhea, North America
                                                                                           tuated only to an insignificant extent.
                                                                                           Within the Caribbean, Haiti showed a
                                                                                           33% incidence of travelers' diarrhea,
                                                                                           as compared with 15% to 19% on any
                                                                                           of the other islands (Antigua, Bar¬
                                                                                           bados, Guadeloupe, Martinique, and
                                                                                           St Lucia).

                                                                                                  Chronology         of Diarrhea
                                                                                              The onset of travelers' diarrhea
                                                                                           was usually early in the course of the
                                                                                           stay abroad (Fig 1). In the tropics,
                                                                                           diarrhea developed in 62% of the
                                                                                           patients within one week. In each
                                                                                           investigated region, including North
                                                                                           America, the third day showed the
20   H                                                                                     highest rate of onset. Subgroups with
                                                                                           concomitant symptoms (fever, vomit¬
                                                                                           ing, abdominal cramps, or observa¬
                                                                                           tion of blood or mucus in the stools)
                                                                                           showed no distinctly different pattern
                                                                                           of onset, neither did the various age
                       5         7        9           11    13          15                 groups, nor persons with loose mo¬
                          Duration of Diarrhea, Days                                          The duration of diarrhea was usu¬
                                                                                           ally short. Fifty-five percent of those
                                                                                           in the tropics who were affected by
                                                                                           diarrhea and 65% of all those
                                                                                           affected in North America were
                            Fig 2.—Duration of diarrhea.
                                                                                           asymptomatic within 48 hours (Fig 2).
                                                                                           In the subtropics, this proportion var¬
                                                                                           ied from 42% in Tunisia to 61% on
                                                                                           Rhodes. In the tropics, the mean
         Fig 3.—Duration of diarrhea compared with day            of onset.
                                                                                           duration for all cases of diarrhea was
                                                                                           3.2 ± 0.2 days when none of the afore¬
                                                                                           mentioned concomitant symptoms
                                                                                           had occurred, and 4.0 ±0.2 days with
                                                                                           any one of them. Thus, the mean
                                                                Tropics                    duration was 3.6 ±0.1 days (median,
                                                                Subtropics                 2.3 days) for all cases of tropical
                                                                                           travelers' diarrhea and 2.9 ±0.3 days
                                                                                           (median, 2.0 days) for tropical loose
                                                                                           motions. No significant differences
                                                                                           were detected between destinations.
                                                                                           In North America, diarrhea lasted for

                                                  -A-5-n                                   a mean of 2.9 ±0.5 days (median, 1.8
                                                                                           days). These values do not describe
                                                                                           untreated disease, as our population
i    -

                                                                                           used various therapeutic agents.8 In
                                                                                           the 918 (26%) of 3,554 tropical cases
         -i-1-1-r                        T-r-                                  1-r—
         2            4              6            8        10            12           14
                                                                                           that remained completely untreated,
                                                                                           the mean duration was 4.1 ±0.2 days
             Onset of Diarrhea With Respect to Length of Stay in      Tropics, Days        (median,   2.4   days).
                                                                                             Older persons were inconvenienced
                                                                                           for a significantly shorter period
                                                                                           (P<.01). Whereas the duration of

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                                                                                                 concomitant symptoms, a parallel
                                                                                                 trend was observed. This tendency
                                                                                                 was found in both sexes and in all
                                                                                                 groups with identical travel charac¬
                                                                                                 teristics or destinations. Men, persons
                                                                                                 younger than 30 years and those older
                                                                                                 than 75 years, and travelers on multi-
                                                                                                 destination tours tended to follow the
                                                                                                 recommendations less meticulously or
                                                                                                 not at all.
                                                                                                    A considerable proportion of the
                                                                                                 10,555 visitors to the tropics (42%,
                                                                                                 n=4,426) used prophylactic or thera¬
                                                                                                 peutic intestinal drugs, some taking
                                                                                                  more than one agent: 22% (n=2,298)

                                                                                                 iumbromide(Mexaforme);8% (n=830)
                                                                                                 clioquinol (Entero-Vioforme); 1%
                                                                                                 (n=108) broxyquinoline (Intestopan);
                                                                                                 14% (n=l,430) other, eg, diphenox-
                                                                                                 ylate hydrochloride, difenoxine hy-
                                                                                                 drochloride, and activated charcoal.
                                                                        basis of maximal daily
                                                                                                 Additionally, 9% (n=892) took antibi¬
Fig 4.—Severity of diarrhea in various climatic regions assessed   on
                                                                                                 otics   orsulfamethoxazole-trimetho-
frequency of bowel movements.
                                                                                                 prim,   4% purely for prophylaxis of
diarrhea in the tropics ranged from             tropics. Differentiation into watery             diarrhea or venereal disease. Of the
4.0 to 4.2 days for persons 30 years            and unformed stools only disclosed               6,983 persons unaffected by diarrhea,
and younger, it was 3.6 days for those          that the latter usually occur in milder          15% (n=l,061) consumed intestinal
aged 30 to 39 years, and 2.9 to 3.2 days        cases. Abdominal cramps were partic¬             drugs purely for prophylaxis. In the
for all age groups older than 39 years.         ularly frequent in women and in the              subtropics, the proportion of self-
Mainly in the tropics, the duration             age groups and those with destina¬               medication was less, varying much
was shorter the later the ailment               tions at which high rates of diarrhea            from region to region. As duration
occurred (Fig 3) (P<.001). No signifi¬          occurred (P<.001). Adventure-tour                and dosage of this heterogenous med¬
cant influence was attributable to the          participants were more prone to cases            ication was not noted, and as it was
person's sex or a history of previous           with fever   (P=.02).                            not controlled by placebo, its efficacy
tropical journeys.                                                                               could not be assessed.
                                                          Preventive Measures
           Symptomatology                          Avoidance of a long list of food and                         COMMENT
  Diarrhea usually takes a mild                 beverages'10 is traditionally rec¬                   The incidence of travelers' diarrhea
course when severity is defined by the          ommended to prevent travelers'                    as  presented by different authors
number of stools on the worst day.              diarrhea. The benefit of such self-               must be compared carefully. First,
More than 75% of persons with trav¬             restriction was investigated for trav¬            there are variations in definition.
elers' diarrhea in the tropics never            elers to the tropics. The overall diar-           Second, daily evaluation" or a "diar¬
had   more   than five bowel movements          rheal incidence in the tropics (33.9%)            rhea diary"7 are the most reliable
per  day (Fig 4). The mean maximal              was taken as a standard of compari¬               methods for compiling data but would
                                                son and given the value of 1.00. The              never be allowed by tour operators.
daily stool frequency was 4.6 ±0.1
(median, 4.0) in the tropics and                ratio was 0.88 (P<.001) in those 3,382            Third, the year of study is important,
3.6 ±0.2 (median, 3.4) in North Ameri¬          persons who stated that they had not              as regions may have improved or

ca. The untreated patients in the               used dietary restriction, 0.97 (not sig¬          deteriorated. Fourth, the length of
tropics reported 3.9 ± 0.1 (median, 3.4)        nificant) in the 1,518 travelers who              stay abroad varies. Fifth, various cat¬
defecations. There was no significant           only avoided tap water, but 1.08                  egories of populations were investi¬
difference between age groups. A                (P<.01) in the 2,530 travelers who                gated. Bearing in mind these reserva¬
slightly more severe course in women            followed just one (any one) current¬              tions, our worldwide study is consist¬
(4.80 ±0.09 stools as compared with             ly recommended precaution,' 1.09                  ent with regional ones.
4.54 ±0.07 in men) is due to a higher           (P<.001) in 5,966 travelers who took                 The occurrence of travelers' diar¬
proportion of women (25.6% ) who had            any number and type of precautions,               rhea depends on who you are, where
six or more bowel movements as                  and 1.13 (P<.001) in those 1,041 trav¬            you go, and how you live.12 Concerning
opposed to 22.0% of men (P=.001). No            elers who took at least three precau¬             who you are, not only does the coun¬
significant differences were found              tions. Thus, diarrhea seemed to occur             try of origin play a role,""'3 but so do a
with respect to regions, former jour¬           more frequently the more a person                 history of previous gastrointestinal
neys to the tropics, or travel charac¬          tried to elude it! In the 10.5% of                tract illness8'" and age. One wonders
teristics. No significant correlation           travelers who suffered relatively se¬             whether younger persons are more
was detectable between severity and             vere diarrhea with six or more bowel              vulnerable because of Gargantuan
duration of    cases   of diarrhea in the       movements, and in each group with                 appetite or weaker immunity. This

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age-related difference has been de¬                  be due to     a demographic artifact                  expression of a severe course, rather
scribed discordantly.1516 Despite sta¬               (digit preference) rather than a pro¬                 than of specific etiology.
tistical significance, former trips to               portion with prolonged incubation or                     Clinical similarities in all regions,
the tropics do not reduce diarrheal                  a second infection, has been ob¬                      including North America, are consist¬
incidence by a substantial degree.                   served previously." The gradually                     ent with analogous causative agents
This would be consistent with a short                shorter duration of illness among                     everywhere. This hypothesis ought to
duration of acquired immunity." Pre¬                 cases occurring later in the course of                be confirmed by an intensified search
vious visits to the same region were                 the stay suggests an improved de¬                     for these organisms in the cases of
not recorded, but unpublished data                   fense mechanism. A shorter duration                   travelers' diarrhea occurring in devel¬
for a similar population8 did not show               of illness in older tourists might be                 oped, low-risk areas. For obvious rea¬
a much reduced incidence, even if the                explained by a smaller appetite with                  sons, etiology could not be further
traveler had been to the same area                   reduced intake of pathogens. As the                   evaluated in our descriptive study.
more than twice.                                     travelers did not take medication                        Dietary self-restraint did not help
   Concerning where you go, our data                 along with a controlled study, no                     this and most other101318 populations
provide appropriate and detailed ad¬                 conclusions can be drawn on compari¬                  examined. This might, among other
vice for high-risk or apprehensive                   son of the treated v untreated popula¬                reasons,   be due to differences in
travelers. The incidence depends                     tions. In the untreated group, diar¬                  recall. To be certain about the role of
more on the quality of sanitation                    rhea was prolonged by about 0.5 days                  the conventional nutritional recom¬
facilities than on the climate.'"7                   compared with the overall results,                    mendations,          a    prospective study
Accordingly, some of the Tunisian                    reflecting   a   marginally longer natu¬              should be undertaken. Meanwhile, in
hotels with a high diarrheal incidence               ral course.      The slightly diminished              view of the unreliable hygienic condi¬
have been notified and a follow-up                   number of defecations in the un¬                      tions in many hotels, airline catering
study is planned. Within the selected                treated population might be due to                    stations,"'20 and cruise ships, it is
group of charter-flight tourists, the                the fact that the groups could not be                 certainly logical to continue to advo¬
how (travel characteristics) may play                randomized and that usually more                      cate the traditional and ever-repeated
a minor role only.10 These tourists                  severely affected tourists inevitably                 rules.' However, it must be kept in
seem   to have quite a homogenous                    seek the aid of some medication.                      mind that "forbidden dishes" cannot
standard of hygiene, although the                       Epidemiologically, there is no evi¬                be banned from the menus by physi¬
brochures offer various types of vaca¬               dence that loose motions are an                       cians, that there is rarely an alterna¬
tion at the same destination. Data for               entirely separate, eg, functional, enti¬              tive to the almost ubiquitous cold
formerly       investigated,       more       re¬    ty to be distinguished from travelers'                buffet luncheons, and that the major¬
stricted populations, such as Peace                  diarrhea. The parallels in chronology                 ity of vacationers apparently will
Corps volunteers and students, differ                and symptomatology are compatible                     always succumb to gastronomic temp¬
widely from ours. The data therefore                 with a mild form of the same disease.                 tations.
cannot be extrapolated safely for the                It therefore is not logical to limit
                                                                                                             This study was partly supported by the Swiss
largest group of travelers: the tour¬                studies to the more severe form or to                 National Science Foundation (grant 6.181-0.76)
ists.                                                types of diarrhea accompanied by                      and the Jubilee Foundation of the Swiss Life
                                                                                                           Insurance and Pension Company.
   Travelers' diarrhea usually takes a               watery stools only.                                     Airline managements, all participating cabin
short and mild course. Nevertheless,                    The gradual correlation of high                    crews, and especially E. Bleuler, Balair, Switzer¬
this ailment can ruin a stay abroad,                 incidence, high rate with early onset,                land, and Brigitte Kreitmayr, Condor-Flug-
                                                     and prolonged duration at various                     dienst, Germany, provided invaluable help with
leading to a lack of rest and mobility                                                                     the questionnaires. Otto Gsell, MD, provided
and to a feeling of insecurity and                   destinations is suggestive of quantita¬               critical advice, Remo Roth provided statistical
frustration in a period of high expec¬               tive variations in ingested pathogenic                assistance, Beth Urech-Rankin made linguistic
                                                                                                           corrections, and Claudia Seiferle, Elisabeth
tations. The early onset, even the                   organisms. The concomitant symp¬                      Herold, and Carita Frei provided secretarial
small second peak (Fig 1), which may                 toms described seem rather to be the                  help.
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