S U P P L E M E N T A R T I C L E
Travel-Associated Enteric Infections Diagnosed
After Return to the United States, Foodborne
Diseases Active Surveillance Network (FoodNet),
Magdalena E. Kendall,1,2Stacy Crim,1Kathleen Fullerton,1Pauline V. Han,1Alicia B. Cronquist,3
Beletshachew Shiferaw,5L. Amanda Ingram,6Joshua Rounds,4Eric D. Mintz,1and Barbara E. Mahon1
1Centers for Disease Control and Prevention;2Atlanta Research and Education Foundation, Atlanta, Georgia;3Colorado Department of Public Health and
Environment, Denver;4Minnesota Department of Health, St Paul;5Oregon State Public Health Division, Portland;6Tennessee Department of Health,
data from the Foodborne Diseases Active Surveillance Network (FoodNet), we describe travel-associated enteric
infections during 2004–2009, characterizing the patients, pathogens, and destinations involved.
Methods.FoodNet conducts active surveillance at 10 US sites for laboratory-confirmed infections with
9 pathogens transmitted commonly through food. Travel-associated infections are infections diagnosed in the
United States but likely acquired abroad based on a pathogen-specific time window between return from
international travel to diagnosis. We compare the demographic, clinical, and exposure-related characteristics of
travelers with those of nontravelers and estimate the risk of travel-associated infections by destination, using US
Department of Commerce data.
Results.Of 64 039 enteric infections reported to FoodNet with information about travel, 8270 (13%) were
travel associated. The pathogens identified most commonly in travelers were Campylobacter (42%), nontyphoidal
Salmonella (32%), and Shigella (13%). The most common travel destinations were Mexico, India, Peru, Dominican
Republic, and Jamaica. Most travel-associated infections occurred in travelers returning from Latin America and the
Caribbean (LAC). Risk was greatest after travel to Africa (75.9 cases per 100 000 population), followed by Asia (22.7
cases per 100 000), and LAC (20.0 cases per 100 000).
Conclusions.The Latin America and Caribbean region accounts for most travel-associated enteric infections
diagnosed in the United States, although travel to Africa carries the greatest risk. Although FoodNet surveillance
does not cover enterotoxigenic Escherichia coli, a common travel-associated infection, this information about other
key enteric pathogens can be used by travelers and clinicians in pre- and posttravel consultations.
Approximately 40% of US travelers to less developed countries experience diarrheal illness. Using
Diarrheal illness is often experienced by US travelers
to other countries [1, 2]. The World Health Organi-
zation (WHO) estimates that 15–20 million travelers
to developing countries experience diarrhea annually ;
40% of US travelers to less developed countries are
estimated to contract diarrheal illness due to Salmonella,
Campylobacter, enterotoxigenic Escherichia coli (ETEC),
and other enteric pathogens . Travelers usually be-
come infected by ingesting food or water contami-
nated with these pathogens [5, 6]. Knowledge of the
epidemiology of travel-associated enteric infections
can help improve US traveler health and prevent
morbidity and mortality by improving pre- and
posttravel consultations and enhancing public health
No surveillance system monitors enteric infections
globally, although many countries, including the United
States, have national enteric disease surveillance systems
in place. Indeed, investigators from Sweden and Finland
Correspondence: Magdalena E. Kendall, MPH, Centers for Disease Control and
Prevention, 1600 Clifton Rd NE, Mailstop C-09, Atlanta, GA 30333 (mkendall@
Clinical Infectious Diseases
Published by Oxford University Press on behalf of the Infectious Diseases
Society of America 2012.
d CID 2012:54 (Suppl 5)
d Kendall et al
by guest on December 22, 2015
STEC O157. Domestically acquired STEC infections are also
more often caused by STEC O157 than by non-O157; our re-
sults are consistent with previous studies showing that STEC
non-O157 infections are relatively less common in the United
States than in other countries .
The results of this study are most useful for comparisons
across regions and pathogens, not as an indication of the
absolute risks of enteric illness with travel to specific regions.
The data on air travelers do not capture the amount of time
spent abroad and are a unit of arrivals, not persons, but are the
best proxy for person-time exposed to other countries of which
we are aware. In FoodNet, travel-associated infections are
reported only if diagnosed after return to the United States.
Even if symptoms continue after return to the United States,
ill persons may not seek medical care or may not submit
a specimen for laboratory testing. When a specimen is sub-
mitted, it may not yield the pathogen causing the illness, or
as is commonly the case for ETEC, the laboratory may not
seek evidence of the pathogen [2, 5, 22]. These factors all tend
to lead to an underestimate of the number of infections. On the
other hand, because all infections diagnosed in the FoodNet
postreturn exposure window are attributed to travel, some
infections acquired in the United States may have been in-
correctly categorized as travel associated. Other investigators
have used shorter travel windows before illness onset to define
travel-associated infections . Any overestimation resulting
from misclassification of illnesses as travel associated is likely
to be small, though, and, to the extent that these illnesses were
caused by exposures occurring in the United States, would tend
to obscure differences between travel destinations.
Patterns of risk of enteric infection vary greatly in and among
world regions; these patterns likely provide insights into the
exposures not only of travelers but also of residents. Travelers
and clinicians may use this information and pre- and posttravel
consultations to aid in assessing health risks and to help in
differential diagnosis of infections.
contributions to this manuscript, and the health departments and public
health laboratories at FoodNet sites.
Disclaimer.The contents of this work are solely the responsibility of
the authors and do not necessarily represent the official views of the
Centers for Disease Control and Prevention.
Supplement sponsorship.This article was published as part of a sup-
plement entitled ‘‘Studies From the Foodborne Diseases Active Surveil-
lance Network,’’ sponsored by the Division of Foodborne, Waterborne,
and Environmental Diseases of the National Center for Emerging and
Zoonotic Infectious Diseases from the Centers for Disease Control and
Prevention, and the Association of Public Health Laboratories.
Potential conflicts of interest. All authors: No reported conflicts.
All authors have submitted the ICMJE Form for Disclosure of Potential
Conflicts of Interest. Conflicts that the editors consider relevant to the
content of the manuscript have been disclosed.
We thank Effie Booth and Mark Sotir for their
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