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---, "Influenza in travellers to Alaska, the Yukon Territory, and on west coast cruise ships, summer of 1999," Canada Communicable Disease Report, 1999, 25:16, 137-141

An outbreak of influenza A is reported among tourists who travelled to Alaska, USA, and the Yukon Territory, Canada, on 7 separate week-long cruises between 22 May and 28 June 1999, with reports of 428 cases of acute respiratory illness (ARI) being received by 29 June. Of 386 ill persons for whom dates of illness onset were known, 187 (48%) had onset before or within 48 h of boarding a cruise ship, which suggested that transmission had occurred during a preceding land-based tour. Incidence of ARI was 3.8% (386 of 10110 passengers) and the ARI attack rate was 5.5 per 1000 passenger days. 132 (34%) of the ARI cases met the criteria for influenza-like illness (ILI). Four travellers were hospitalized for pneumonia. 104 cases of ARI were reported among tourism workers. Nine influenza A isolates from tourists in Alaska were taken in the last half of June; no further ones had been reported as of 15 July. 13 influenza A isolates were taken from the whole population of the Yukon Territory, 6 of them reported in the week before 15 July. No reports of influenza A among the resident population of British Columbia were received, however, 2 influenza A isolates were reported from cruise ship passengers arriving in Vancouver. All isolates were found to be A/Sydney/5/97 (H3N2)-like. As of 15 July, no increases in ILI or ARI had been found in the general populations of Alaska, British Columbia or the Yukon Territory