Looking for Evidence that Personal Hygiene Precautions Prevent ...

their results if we limit our focus to the group of participants
from the United States and Canada. Of this group, 597 (58%)
of 1029 attendees returned questionnaires. Of these 597 persons,
325 (54%) reported at least 1 episode of traveler’s diarrhea.
The questionnaire specifically asked whether the person
drank bottled liquids or avoided salads, raw vegetables, and
unpeeled fruit. The attack rate of traveler’s diarrhea among
persons who said that they took these precautions was the same
as that among those who said that they did not take these
precautions. The conclusion of these authors was that “drinking
bottled liquids, and avoiding salads, raw vegetables, and unpeeled
fruits also failed to prevent illness” [2, page 530].
Mexico, 1976. The second study, by Merson et al. [3], was
also performed at a medical conference in Mexico. The subjects
included 73 physicians and 48 of their family members who
were attending the Fifth World Congress of Gastroenterology
in Mexico City in October 1974. Traveler’s diarrhea occurred
in 59 persons (49%). This highly motivated group of participants
provided stool specimens before, during, and after their
1–2-week trip to Mexico. In addition, the 73 physicians provided
a serum sample before and after the trip.
A questionnaire was given to all participants 10 days after
they left Mexico. The questionnaire contained questions regarding
the consumption of food and water while in Mexico.
All participants completed the questionnaire. The authors concluded
that “illness was not associated with consumption of
water or iced beverages.…Illness was similarly not associated
with consumption of vendor food, salads containing raw vegetables,
other raw vegetables, or unpeeled fruits” [3, page 1303].
However, the subgroup of participants who acquired infections
with enterotoxigenic Escherichia coli had eaten salads containing
raw vegetables significantly more often than had noninfected
participants ( ). This increased risk was not associated
P p .014
with consumption of other raw vegetables or unpeeled fruits.
Mexico and Peru, 1978. Chang distributed questionnaires
to charter passengers returning from Mexico ( ) and
n p 162
Peru ( ) [4]. The questionnaires inquired about the sen
p 65
verity and number of episodes of traveler’s diarrhea and the
risk factors for acquiring traveler’s diarrhea. Eighty-two percent
of the travelers to Mexico experienced traveler’s diarrhea,
whereas 60% of the travelers to Peru reported traveler’s diarrhea.
The author noted, “Avoidance of tap water, uncooked
foods, and ice cubes did not make a difference in the outcome”
[4, page 429]. No details about individual risk factors are given.
Worldwide, 1983. Steffen et al. [5] surveyed nearly 10,000
tourists about their food precautions and risk of acquiring traveler’s
diarrhea in various destinations worldwide. For a 22month
period, a questionnaire was handed out by air crew
members on flights returning to Switzerland and Germany from
numerous international destinations. A total of 16,568 questionnaires
were distributed, and 60.2% were completed and
S532 • CID 2005:41 (Suppl 8) • Shlim
returned. The rates of traveler’s diarrhea in developing countries
were 30%–57%. Steffen et al. [5] used a unique method
of evaluating the rate of traveler’s diarrhea among tourists who
applied different levels of food precautions. The baseline rate
of diarrhea in all travelers (33.9%) was given the value of 1.0.
The results are shown in table 1. The table demonstrates that,
in a retrospective study of traveler’s diarrhea, subjects who
appeared to exercise more caution were at increased risk of
acquiring traveler’s diarrhea. Or, as the authors stated: “Thus,
diarrhea seemed to occur more frequently the more a person
tried to elude it!” [5, page 1179], Even if we ignore, for the
moment, the inverse relationship between dietary precautions
and the recall of having experienced traveler’s diarrhea, the
study certainly did not provide evidence that tourists who were
more cautious about what they chose to eat were protected
against traveler’s diarrhea.
Steffen et al. [5] also noted a differential risk between resort
hotels, even at the same general destination. A 2-month survey
of 21 hotels in Tunisia, with a minimum of 20 tourists at each
hotel during that period, revealed an incidence of traveler’s diarrhea
that varied from 26% to 89%. Thus, the source of food
(i.e., the individual hotels), not the choice of foods, appeared to
make a large difference in the risk of acquiring traveler’s diarrhea.
Worldwide (children), 1991. Data on the risk of acquiring
traveler’s diarrhea in traveling children are scarce. Pitzinger et
al. [6] performed the one study that focused on the risk and
severity of traveler’s diarrhea in a retrospective study of traveling
Swiss families. Families that had sought pretravel advice
and that had children between the ages of 0 and 20 years were
sent questionnaires within 2 weeks of their return from a trip
to the tropics or subtropics. Questionnaires were sent to households
of 446 young travelers, and 363 (81.4%) of the questionnaires
were returned and evaluated. The population of children
was stratified according to age, as follows: 0–2 years (n
p 20); 3–6 years ( n p 47); 7–14 years ( n p 46);
and 15–20
years ( n p 250).
Surprisingly, 60.1% of the respondents (n p
218) stated that they took no personal hygiene precautions.
Thirty-eight percent of the travelers stated that they regularly
employed preventive measures with regard to eating. Parents
Table 1. Food precautions taken by travelers versus the risk
of acquiring traveler’s diarrhea, compared with the average risk
of acquiring traveler’s diarrhea.
Food precaution
No. of
travelers
Risk
value P
No precautions 3382 0.88 !.001
Avoided tap water only 1518 0.97 NS
Followed 1 recommended precaution 2530 1.08 !.01
Any no. and type of precaution 5966 1.09 !.001
Took 3 precautions 1041 1.13 !.001
NOTE. The risk of acquiring traveler’s diarrhea appears to increase with
increasing adherence to food precautions. Adapted from Steffen et al. [5]. NS,
not significant.
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