title: Influenza in long-term Dutch travelers in the tropics: symptoms and infections.
abstract: BACKGROUND
  Influenza is a common infection among travelers, and attack rates are well documented in short-term travelers and holiday makers. Little data exists on long-term, non-expatriate travelers.
  
  
  METHODS
  This was a prospective mono-centre study of immunocompetent, Dutch travelers aged ≥18 to 64 years. It was conducted at the Public Health Service travel clinic in Amsterdam from December 2008 to September 2011, and included all travelers intending to travel to a tropical or sub-tropical country.
  
  
  RESULTS
  Among 602 Dutch long-term travelers to tropical regions, 82 % had protective influenza antibody titres pre-travel. The influenza attack rate of serologically confirmed infection during travel was 15 %, and of symptomatic infection was 6.3 % (fever alone) and 2 % (ILI), respectively.
  
  
  CONCLUSIONS
  The attack rate in this study is similar to seasonal rates of infection in the general population. Influenza vaccination pre-travel is therefore most important for people at risk of medical complications due to influenza.
authors.affiliation: Department of Infectious Diseases, Public Health Service Amsterdam, Nieuwe Achtergracht 100, 1018WT, Amsterdam, The Netherlands.
authors.forename: Jane
authors.initials: J
authors.lastname: Whelan
authors.affiliation: Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Guus F
authors.initials: GF
authors.lastname: Rimmelzwaan
authors.affiliation: Department of Infectious Diseases, Public Health Service Amsterdam, Nieuwe Achtergracht 100, 1018WT, Amsterdam, The Netherlands.|Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Anneke
authors.initials: A
authors.lastname: van den Hoek
authors.affiliation: Department of Infectious Diseases, Public Health Service Amsterdam, Nieuwe Achtergracht 100, 1018WT, Amsterdam, The Netherlands.|Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Sanne-Meike
authors.initials: SM
authors.lastname: Belderok
authors.affiliation: Department of Infectious Diseases, Public Health Service Amsterdam, Nieuwe Achtergracht 100, 1018WT, Amsterdam, The Netherlands. gsonder@ggd.amsterdam.nl.|Academic Medical Centre, Amsterdam, The Netherlands. gsonder@ggd.amsterdam.nl.|National Coordination Centre for Traveler's Health Advice, Amsterdam, The Netherlands. gsonder@ggd.amsterdam.nl.
authors.forename: Gerard J B
authors.initials: GJB
authors.lastname: Sonder
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D005260:Female; D006801:Humans; D015994:Incidence; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification; D009981:Influenza B virus / Q000276:immunology / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology / Q000276:immunology / Q000473:pathology* / Q000821:virology; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D016017:Odds Ratio; D011446:Prospective Studies; D014195:Travel; D014611:Vaccination; D044465:White People; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral
keywords: Attack rate; Influenza; Seroconversion; Travelers