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Outbreak Notice Outbreak of Influenza A Infection -- Alaska and the Yukon Territory, June-July 1998

Since July 26, CDC and Health Canada, in cooperation with local public health authorities, have been investigating reports of febrile respiratory illness and associated pneumonia among persons traveling on land and sea, both independently and on tour packages, in Alaska and the Yukon Territory. Commonly reported symptoms include fever and cough, and laboratory evidence suggests that influenza A infection may be a cause of many of the illnesses. Summertime outbreaks of Influenza A have previously been reported among tourists in the United States and Canada (1,2). No evidence suggests increased respiratory illness activity among residents of these areas.

From June 5 through August 4, 1998, a total of 419 cases of acute respiratory infection (ARI), including 20 cases of pneumonia during June-July, have been reported to the investigation team in Anchorage. No deaths have been reported. The median age of persons with ARI is 63 years (range: 3-88 years); the median age of persons with pneumonia is 74 years (range: 61-88 years). Many cases have occurred in clusters, particularly among groups of 40-50 passengers sharing common transportation and accommodation packages on overland tours between Anchorage and Skagway or Anchorage and Seward during June-July. Affected passengers have traveled on several different tours from different companies. Information from case reports suggests that after touring inland, ill persons are boarding cruise ships, possibly resulting in further spread. In some instances, travelers are becoming ill and seeking medical attention for their respiratory illnesses only after returning home.

During June-September, approximately 70,000 overland tour and cruise ship passengers visit Alaska and the Yukon Territory each week. Most do not experience febrile respiratory illness. No special prevention measures are recommended at this time for travelers in good health.

Systematic surveillance for febrile respiratory illness and pneumonia is being initiated by CDC, Health Canada, and other public health officials in the region to better define the scope of the outbreak. Health-care providers who see patients with febrile respiratory illness and/or pneumonia should obtain a travel history and consider influenza A in the differential diagnosis for those with recent travel to Alaska or the Yukon Territory. Additional cases should be reported to CDC's Special Investigation Team; telephone (907) 729-3431; fax (907) 729-3429; or e-mail,

Reported by: Alaska Dept of Health and Social Svcs; Bur of Infectious Diseases and Office of Special Health Initiatives, Laboratory Center for Disease Control, Occupational Health and Safety Agency, Health Canada, Ottawa. Arctic Investigations Program, Div of Viral and Rickettsial Diseases and Div of Quarantine, National Center for Infectious Diseases; and EIS officers, CDC.


  1. CDC. Outbreak of influenza-like illness in a tour group, Alaska. MMWR 1987;36;697-8,704.

  2. Miller J, Tam T, Afif C, et al. Influenza A outbreak on a cruiseship. Canada Communicable Disease Report 1998;24:9-11.

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