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Original Research |

GeoSentinel Surveillance of Illness in Returned Travelers, 2007–2011

Karin Leder, MBBS, MPH, PhD; Joseph Torresi, MBBS, PhD; Michael D. Libman, MD; Jakob P. Cramer, MD, MSc; Francesco Castelli, MD, PhD; Patricia Schlagenhauf, PhD; Annelies Wilder-Smith, MD, PhD, MIH; Mary E. Wilson, MD; Jay S. Keystone, MD, MSc; Eli Schwartz, MD; Elizabeth D. Barnett, MD; Frank von Sonnenburg, MD, PhD; John S. Brownstein, PhD; Allen C. Cheng, MBBS, PhD, MPH; Mark J. Sotir, PhD, MPH; Douglas H. Esposito, MD, MPH; David O. Freedman, MD, for the GeoSentinel Surveillance Network*
[+] Article and Author Information

* For a list of GeoSentinel Surveillance Network members, see the Appendix.


From Victorian Infectious Disease Service, Royal Melbourne Hospital, Monash University, Austin Hospital, Melbourne University, and Alfred Hospital, Melbourne, Victoria, Australia; Centre for Tropical Diseases, McGill University, Montreal, Quebec, and Tropical Disease Unit, Toronto General Hospital and University of Toronto, Toronto, Ontario, Canada; University Medical Center Hamburg-Eppendorf, Hamburg, Institute of Public Health, University of Heidelberg, Heidelberg, and University of Munich, Munich, Germany; University of Brescia, Brescia, Italy; Centre for Travel Medicine, World Health Organization Collaborating Centre for Travelers' Health, University of Zurich, Zurich, Switzerland; Harvard School of Public Health, Maxwell Finland Laboratory for Infectious Diseases, Boston Medical Center, Boston Children's Hospital, and Harvard Medical School, Boston, Massachusetts; Center of Geographic Medicine, Sheba Medical Center, Tel Hashomer, and Tel Aviv University, Tel Aviv, Israel; National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; and Gorgas Center for Geographic Medicine, University of Alabama at Birmingham, Birmingham, Alabama.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Acknowledgment: The authors thank Elena Axelrod, Charles Miller, Kathy Smith, and the staff at each GeoSentinel site for data, programming, and administrative support; Surendra Karki, MD, for his assistance with the graphics; and Adam Plier for invaluable skills in network coordination and editorial support.

Grant Support: The GeoSentinel Surveillance Network is funded through a cooperative agreement with the Centers for Disease Control and Prevention (grant 5U50CI000359) and with funding from the International Society of Travel Medicine.

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M12-1036.

Reproducible Research Statement: Study protocol and statistical code: Available from Dr. Freedman (e-mail, freedman@uab.edu). Data set: Not available.

Corresponding Author: Karin Leder, MBBS, MPH, PhD, Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria 3004, Australia; e-mail, karin.leder@monash.edu.

Current Author Addresses: Dr. Leder: Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria 3004, Australia.

Dr. Torresi: Infectious Disease Department, Austin Hospital, Level 7, Harold Stokes Building, 145 Studley Road, Heidelberg, Victoria 3084, Australia.

Dr. Libman: McGill University, Room A5-156, 1650 Cedar Avenue, Montreal, Quebec H3G1A4, Canada.

Dr. Cramer: Section for Tropical Medicine, Department of Tropical Medicine, Bernhard Nocht Clinic, University Medical Centre Hamburg-Eppendorf, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany.

Dr. Castelli: University Division of Infectious and Tropical Diseases, University of Brescia, Piazzale Spedali Civili 1, 25123 Brescia, Italy.

Dr. Schlagenhauf: University of Zürich Centre for Travel Medicine, University of Zurich, Hirschengraben 84, CH-8001 Zurich, Switzerland.

Dr. Wilder-Smith: Institute of Public Health, University of Heidelberg, Im Neuenheimer Feld 365, 69120 Heidelberg, Germany.

Dr. Wilson: 1812 Kalorama Square Northwest, Washington, DC 20008-4022.

Dr. Keystone: Tropical Disease Unit, Toronto General Hospital, 200 Elizabeth Street, 13N 1347, Toronto, Ontario M5G 2C4, Canada.

Dr. Schwartz: Center for Geographic Medicine, Chaim Sheba Medical Center, 52621 Tel Hashomer, Israel.

Dr. Barnett: Maxwell Finland Laboratory for Infectious Diseases, Boston Medical Center, 670 Albany Street, Boston, MA 02118.

Dr. von Sonnenburg: International Medicine & Public Health, University of Munich, Georgenstr 5, D-80799 Munich, Germany.

Dr. Brownstein: Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115.

Dr. Cheng: Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria 3004, Australia.

Drs. Sotir and Esposito: Centers for Disease Control and Prevention, Division of Global Migration & Quarantine/Travelers' Health Branch, 1600 Clifton Road Northeast, Mailstop E-03, Atlanta, GA 30333.

Dr. Freedman: Gorgas Center for Geographic Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, 1720 2nd Avenue South, BBRB 203, Birmingham, AL 35294-2170.

Author Contributions: Conception and design: K. Leder, J. Torresi, J.P. Cramer, F. Castelli, P. Schlagenhauf, A. Wilder-Smith, E. Schwartz, F. von Sonnenburg, A.C. Cheng, D.O. Freedman.

Analysis and interpretation of the data: K. Leder, J. Torresi, M.D. Libman, J.P. Cramer, F. Castelli, P. Schlagenhauf, M.E. Wilson, J.S. Keystone, E. Schwartz, E.D. Barnett, F. von Sonnenburg, J.S. Brownstein, A.C. Cheng, M.J. Sotir, D.H. Esposito, D.O. Freedman.

Drafting of the article: K. Leder, J. Torresi, M.D. Libman, J.P. Cramer, F. Castelli, P. Schlagenhauf, A. Wilder-Smith, M.E. Wilson, J.S. Keystone, E. Schwartz, J.S. Brownstein, A.C. Cheng, M.J. Sotir, D.O. Freedman.

Critical revision of the article for important intellectual content: K. Leder, J. Torresi, M.D. Libman, J.P. Cramer, F. Castelli, P. Schlagenhauf, A. Wilder-Smith, M.E. Wilson, E. Schwartz, E.D. Barnett, F. von Sonnenburg, J.S. Brownstein, A.C. Cheng, M.J. Sotir, D.H. Esposito, D.O. Freedman.

Final approval of the article: K. Leder, J. Torresi, M.D. Libman, J.P. Cramer, F. Castelli, P. Schlagenhauf, A. Wilder-Smith, M.E. Wilson, J.S. Keystone, E. Schwartz, E.D. Barnett, F. von Sonnenburg, J.S. Brownstein, A.C. Cheng, M.J. Sotir, D.H. Esposito, D.O. Freedman.

Provision of study materials or patients: K. Leder, M.D. Libman, J.P. Cramer, F. Castelli, M.E. Wilson, J.S. Keystone, E. Schwartz, E.D. Barnett, F. von Sonnenburg, D.O. Freedman.

Statistical expertise: F. von Sonnenburg, A.C. Cheng, M.J. Sotir.

Obtaining of funding: D.O. Freedman.

Administrative, technical, or logistic support: K. Leder, M.J. Sotir, D.O. Freedman.

Collection and assembly of data: K. Leder, J. Torresi, M.D. Libman, J.P. Cramer, F. Castelli, P. Schlagenhauf, M.E. Wilson, E. Schwartz, F. von Sonnenburg, J.S. Brownstein, D.O. Freedman.


Ann Intern Med. 2013;158(6):456-468. doi:10.7326/0003-4819-158-6-201303190-00005
Text Size: A A A

Chinese translation

Background: International travel continues to increase, particularly to Asia and Africa. Clinicians are increasingly likely to be consulted for advice before travel or by ill returned travelers.

Objective: To describe typical diseases in returned travelers according to region, travel reason, and patient demographic characteristics; describe the pattern of low-frequency travel-associated diseases; and refine key messages for care before and after travel.

Design: Descriptive, using GeoSentinel records.

Setting: 53 tropical or travel disease units in 24 countries.

Patients: 42 173 ill returned travelers seen between 2007 and 2011.

Measurements: Frequencies of demographic characteristics, regions visited, and illnesses reported.

Results: Asia (32.6%) and sub-Saharan Africa (26.7%) were the most common regions where illnesses were acquired. Three quarters of travel-related illness was due to gastrointestinal (34.0%), febrile (23.3%), and dermatologic (19.5%) diseases. Only 40.5% of all ill travelers reported pretravel medical visits. The relative frequency of many diseases varied with both travel destination and reason for travel, with travelers visiting friends and relatives in their country of origin having both a disproportionately high burden of serious febrile illness and very low rates of advice before travel (18.3%). Life-threatening diseases, such as Plasmodium falciparum malaria, melioidosis, and African trypanosomiasis, were reported.

Limitations: Sentinel surveillance data collected by specialist clinics do not reflect healthy returning travelers or those with mild or self-limited illness. Data cannot be used to infer quantitative risk for illness.

Conclusion: Many illnesses may have been preventable with appropriate advice, chemoprophylaxis, or vaccination. Clinicians can use these 5-year GeoSentinel data to help tailor more efficient pretravel preparation strategies and evaluate possible differential diagnoses of ill returned travelers according to destination and reason for travel.

Primary Funding Source: Centers for Disease Control and Prevention.

Figures

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Figure 1.

Proportion of major syndromic groupings for gastrointestinal, febrile, dermatologic, and respiratory illnesses among ill returned travelers.

IBS = irritable bowel syndrome; ILI = influenza-like illness.

* Each bar represents a mutually exclusive classification. Green bars depict the proportion of each diagnostic category with the given syndromic grouping. White bars depict the proportion with the given specific cause, and the top diagnoses within each of these categories are shown by region in Figure 2.

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Figure 2.

Top identified specific causes for gastrointestinal, febrile, dermatologic, and respiratory illnesses by region among ill returned travelers.

More than 5 diagnoses are shown if >1 cause had equal numbers of cases. These graphs represent proportions, and there is variability in the number of ill travelers represented from panel to panel (shown from largest to smallest traveler numbers). CLM = cutaneous larva migrans; D. fragilis = Dientamoeba fragilis; E. histolytica = Entamoeba histolytica; P. falciparum = Plasmodium falciparum; P. vivax = Plasmodium vivax; PEP = postexposure prophylaxis; SF = spotted fever; TB = tuberculosis.

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Figure 3.

Top 10 specific diagnoses, by main reasons for travel.

CLM = cutaneous larva migrans; P. falciparum = Plasmodium falciparum; P. vivax = Plasmodium vivax; TB = tuberculosis; VFR = visiting friends and relatives.

* Missionary category includes missionaries, volunteers, and researchers. Traveler type was missing in 4 cases, and other reasons for travel (military or medical tourism, which are not shown) accounted for 1% of cases.

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Tables

References

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Comments

Submit a Comment
Occupational travel risk for infection
Posted on April 1, 2013
Paul D. Blanc
University of Califronia San Francisco
Conflict of Interest: None Declared

To the Editor: The surveillance report by Leder and colleagues on illnesses among persons returning from foreign travel provides rich data. The authors, however, could have been both more circumspect in the interpretation of their observations and more catholic in their categorization of travel for work purposes. As noted (Table 4), 7 among 28 deaths (25%) occurred among “business” travelers, even though this category as defined only accounted for 13.6 % of 42173 cases (Table 1), elsewhere (Figure 3), reported as n=5728. Based on this, the authors suggest “that employers consider their potential liability if a consultation before travel is not provided.” The ratio of 8 observed fatalities to its expectation of 3.8 (28 among 41273 multiplied by 5728) is 1.84, which is not statistically significant (95% CI 0.7-3.8) as that of a Poisson variable to its expectation. Moreover, Figure 3 makes clear that the category generally referred to throughout as “missionaries” also includes “volunteers” and “researchers.” The researcher travelers are likely to be salaried employees; many of the others are, at the least, vocational. There was only one death in this group, although 3.2 were expected, that is, in total 8 expected, whereas 9 deaths occurred. In any event, a salaried employee in the U.S. would be precluded from seeking damages beyond the standard “no-fault” coverage of workers compensation. Were pre-travel consultation to be found to protect against fatal outcomes (which this analysis does not purport to show), then surely it would be warranted without invoking tort liability.

References

1. Leder K, Torresi J, Libman MD, et. al. GeoSentinel surveillance of illness in returned travelers, 2007-2011. Ann Intern Med 2013; 158:456-468

2. Bailar JC III. Ederer F. Significance factors for the ratio of a Poisson variable to its expectation. Biometrics 1964; 20:63943.

Author's Response
Posted on April 30, 2013
Karin Leder, MBBS, MPH, PhD, Michael D. Libman, MD, Mark J. Sotir, PhD, MPH
Royal Melbourne Hospital
Conflict of Interest: None Declared

We appreciate your interest in our paper. GeoSentinel’s definition of business travel is “Travel for business or occupational purposes”. Business travelers are a distinct type of traveler (1). Researchers are sometimes akin to business travelers in that they are often salaried employees, but they are included in the alternate category of Missionary/Volunteer/Researcher/Aid Work (MVRA). As a group, MVRAs are comprised largely of people who have chosen to work at these destinations rather than being assigned by an employer to do so. Researchers, many of whom are also volunteers, often have a different motivation for their trip compared with business travelers and potentially may be more knowledgeable about the conditions and health risks they might encounter while traveling.

Regarding the question of statistically expected mortality, GeoSentinel data enable determination of proportions and proportionate morbidity, but cannot provide information regarding absolute risks of travel since data collection is based on ill travelers and a denominator including healthy travelers cannot be discerned from the database. The number of business travelers included in our sample (n= 5278) represents ill business travelers who reported to GeoSentinel sites, and is not a proxy denominator for all business travelers or even all ill business travelers. Therefore the data do not allow us to say that business travelers are at a higher risk of dying than other travelers. Rather, among unwell travelers who were reported by GeoSentinel sites, the number of business travelers who died was striking. This is an important distinction beyond the issue of statistical significance.

As we have no legal background, the phrase regarding liability may have best been omitted. At the same time it remains important to highlight the importance of having employers understand that international travel for work may be associated with potentially preventable health risks and that they should be encouraged to maximally protect their employees.

Reference

1. Chen LH, Leder K, Wilson ME, Busiess travelers: vaccination considerations for this population. Expert rev Vaccines. 2013;12(4):453-66

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