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Uyeki, T. M.;  Zane, S. B.;  Bodnar, U. R.;  Fielding, K. L.;  Buxton, J. A.;  Miller, J. M.;  Beller, M.;  Butler, J. C.;  Fukuda, K.;  Maloney, S. A. and Cetron, M. S.  "Large summertime influenza a outbreak among tourists in Alaska and the Yukon Territory," Clinical Infectious Diseases, 2003, 36:9, 1095-1102

We investigated a large summertime outbreak of acute respiratory illness during May-September 1998 in Alaska and the Yukon Territory, Canada. Surveillance for acute respiratory illness (ARI), influenza-like illness (ILI), and pneumonia conducted at 31 hospital, clinic, and cruise ship infirmary sites identified 5361 cases of ARI (including 2864 cases of ILI [53%] and 171 cases of pneumonia [3.2%]) occurring primarily in tourists and tourism workers (from 18 and 37 countries, respectively). Influenza A viruses were isolated from 41 of 210 patients with ILI at 8 of 14 land sites and 8 of 17 cruise ship infirmaries. Twenty-two influenza isolates were antigenically characterized, and all were influenza A/Sydney/05/97-like (H3N2) viruses. No other predominant pathogens were identified. We estimated that >33000 cases of ARI might have occurred during this protracted outbreak, which was attributed primarily to influenza A/Sydney/05/97-like (H3N2) viruses. Modern travel patterns may facilitate similar outbreaks, indicating the need for increased awareness about influenza by health care providers and travelers and the desirability of year-round influenza surveillance in some regions.