Influenza transmission during a one-year period (2009-2010) in a Sahelian city: low temperature plays a major role.

This work aimed at studying the link between some climatic factors and the occurrence of influenza in Niamey, Niger. Patients with influenza like illness or severe acute respiratory illness were recruited through a sentinel network. A nasopharyngeal swab was sampled and tested for influenza viruses A and B by RT-PCR. Time series of daily counts of influenza cases and climatic factors were linked using a generalized additive model. Among the 320 patients recruited, 76 were confirmed positive for influenza. Influenza cases increased significantly with minimal temperatures and high visibility. This work brings some valuable explanation to the impact of low temperatures on influenza transmission.