The French Military influenza surveillance system (MISS): overview of epidemiological and virological results during four influenza seasons--2008-2012

Influenza is a viral infection caused by a pathogen with considerable ability for genetic mutation, which is responsible for seasonal outbreaks as well as pandemics. This article presents the results of epidemiological and virological monitoring of four successive influenza outbreaks in the French armed forces, for the period 2008 to 2012. The main events monitored were acute respiratory infection (ARI). Weekly incidence rates were calculated by relating cases to the number of servicepersons monitored. In continental France, the incidence rates for ARI and for medical consultation attributable to influenza were highest during the pandemic and decreased to reach their lowest values in 2010–2011 and 2011–2012. In terms of virological results, the 2008–2009 outbreak was mainly due to the A(H3N2) virus, while the 2009–2010 pandemic and the following season saw the emergence of the A(H1N1) pdm09 strain. The last season 2011–2012 was characterised by a predominant circulation of A(H3N2) viruses. Despite some limitations, the MISS represents a good source of information about influenza in young people. Virological results are compatible with those reported by most other influenza surveillance networks, but could be improved by a better knowledge of the other respiratory viruses in circulation in the military community.