Influenza-associated mortality in Thailand, 2006–2011

The global burden of influenza is unknown but thought to be considerable. In 2008, the global estimate of influenza-associated severe acute lower respiratory illness in children <5 years was 1 million cases1 , and the World Health Organization (WHO) suggests that 3-5 million severe cases occur in persons of all ages each 2 . In temperate regions, influenza usually causes annual outbreaks during the winter season (November-March in the Northern Hemisphere and June-September in the Southern Hemisphere)3-4 . In contrast, influenza-associated mortality in subtropical or tropical regions, particularly in developing countries, remains poorly quantified and often underestimated. The pattern of influenza epidemics in tropical regions is less distinct and more diffuse. Seasonal influenza epidemics can sometimes occur twice or more throughout a year 5 . This article is protected by copyright. All rights reserved.