[Influenza A (H1N1) 2009 surveillance on Mayotte island: the challenge of setting up a new system facing the pandemic].

In response to the threat of the pandemic influenza A (H1N1) 2009 virus in Mayotte Island, influenza surveillance needed to be set up in a matter of weeks, to detect the introduction of the pandemic virus and monitor its spread and impact on public health. Surveillance was based on different systems, including a sentinel practitioner network for influenza-like illness, surveillance of the activity at the hospital emergency departments, virological surveillance, surveillance of severe and fatal cases, and data collection on sale of antipyretic and anti-viral drugs. Despite some weaknesses of the surveillance, results showed a good correlation between all systems, describing an epidemic period of approximately 8-9 weeks, with a peak between weeks 37 and 40, followed by a rapid decrease.