Fulltext

Influenza Virus Infection in Travelers to Tropical and Subtropical Countries

Mutsch, Margot ; Tavernini, Michela ; Marx, Arthur ; Gregory, Victoria ; Lin, Yi Pu ; Hay, Alan J. ; Tschopp, Alois ; Steffen, Robert

In: Clinical Infectious Diseases, 2005, vol. 40, no. 9, p. 1282-1287

Add to personal list
    Title
    • Influenza Virus Infection in Travelers to Tropical and Subtropical Countries
    Author
    • Mutsch, Margot. Division of Epidemiology and Prevention of Communicable Diseases and World Health Organization (WHO) Collaborating Centre for Travelers' Health, Zurich, Switzerland
    • Tavernini, Michela. Division of Epidemiology and Prevention of Communicable Diseases and World Health Organization (WHO) Collaborating Centre for Travelers' Health, Zurich, Switzerland
    • Marx, Arthur. Division of Epidemiology and Prevention of Communicable Diseases and World Health Organization (WHO) Collaborating Centre for Travelers' Health, Zurich, Switzerland
    • Gregory, Victoria. WHO Collaborating Centre for Reference and Research on Influenza, National Institute for Medical Research, London, United Kingdom
    • Lin, Yi Pu. WHO Collaborating Centre for Reference and Research on Influenza, National Institute for Medical Research, London, United Kingdom
    • Hay, Alan J.. WHO Collaborating Centre for Reference and Research on Influenza, National Institute for Medical Research, London, United Kingdom
    • Tschopp, Alois. Division of Biostatistics, Institute of Social and Preventive Medicine, University of Zurich, Zurich, Switzerland
    • Steffen, Robert. Division of Epidemiology and Prevention of Communicable Diseases and World Health Organization (WHO) Collaborating Centre for Travelers' Health, Zurich, Switzerland
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Clinical Infectious Diseases, 2005, vol. 40, no. 9, p. 1282-1287. The University of Chicago Press
    Other Version
    Classification
    • Health
    OAI-PMH Identifier
    • oai:doc.rero.ch:295762
    Summary
    Background. Influenza outbreaks have been reported among travelers, but attack rates and incidence are unknown. Methods. A cohort study was conducted. Travelers to subtropical and tropical countries recruited at the University of Zurich Travel Clinic (Switzerland), January 1998 to March 2000, were investigated with pre- and posttravel assessment of hemagglutination inhibition and by questionnaire. Results. Among 1450 travelers recruited who completed questionnaires and provided serum samples before departure, 289 (19.9%) reported febrile illness during or after traveling abroad; of these, 211 (73.0%) provided paired serum samples. Additionally, paired serum samples were collected from 321 frequency-matched afebrile control subjects among the remaining 1161 subjects of the study population. Seroconversion for influenza virus infection was demonstrated in 40 (2.8%) of all travelers; 18 participants (1.2%) had a ⩾4-fold increase in antibody titers. This corresponds to an incidence of 1.0 influenza-associated events per 100 person-months abroad. Among the 211 febrile participants, 27 (12.8%) had seroconversion, 13 (6.2%) with a ⩾4-fold increase; among the 321 afebrile control subjects, 13 (4.0%) had seroconversion, 5 (1.6%) with a ⩾4-fold increase. Twenty-five seroconverters (62.5%; P = .747) acquired influenza outside of the European epidemic season. Sixteen patients (40.0%) sought medical attention either abroad or at home, and 32 (80.0%) were asymptomatic at the time of completion of the survey. Conclusions. This survey indicates that influenza is the most frequent vaccine-preventable infection among travelers to subtropical and tropical countries. Infections occur mainly outside the domestic epidemic season, and they have a considerable impact. Pretravel vaccination should be considered for travelers to subtropical and tropical countries