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Large summertime influenza A outbreak among tourists in Alaska and the Yukon Territory

Timothy M Uyeki1, Suzanne B Zane, Ulana R Bodnar

  • 1Influenza Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. tmu0@cdc.gov

Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America
|April 26, 2003
PubMed

Insights

A large outbreak of acute respiratory illness (ARI) in Alaska and Canada was primarily caused by influenza A (H3N2) viruses. This highlights the need for traveler awareness and year-round influenza surveillance.

Area of Science:

  • Epidemiology
  • Virology
  • Public Health

Background:

  • Large outbreaks of acute respiratory illness (ARI) can significantly impact public health, particularly in regions with high tourist traffic.
  • Summertime outbreaks of influenza are less common but can occur, posing a challenge for surveillance and control.

Purpose of the Study:

  • To investigate a significant summertime outbreak of ARI in Alaska and the Yukon Territory.
  • To identify the causative agent and understand the epidemiology of the outbreak.
  • To assess the role of modern travel in disease transmission.

Main Methods:

  • Conducted surveillance for ARI, influenza-like illness (ILI), and pneumonia across 31 sites (hospitals, clinics, cruise ship infirmaries).
  • Isolated and antigenically characterized influenza viruses from affected individuals.
  • Estimated total ARI cases based on reported data.

Main Results:

  • Identified 5361 cases of ARI, including 2864 ILI and 171 pneumonia cases, predominantly among tourists and tourism workers.
  • Isolated influenza A/Sydney/05/97-like (H3N2) viruses from 41 patients with ILI; no other predominant pathogens were found.
  • Estimated over 33,000 ARI cases occurred during the outbreak, primarily attributed to influenza A (H3N2).

Conclusions:

  • Influenza A (H3N2) was the primary cause of the large summertime ARI outbreak.
  • Modern travel patterns can facilitate the rapid spread of influenza across international borders.
  • Increased healthcare provider and traveler awareness, along with year-round surveillance in certain regions, is recommended.

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