Abstract

In Senegal, the seasonality of influenza epidemics is well defined with a clear peak around August and September (in rainy season which occurs from July to October). Surprisingly, the first detection of the A(H1N1)pdm09 virus was in January 2010 and rapidly reached a high detection peak between January and February, indicating a real shift in the influenza seasonality in Senegal. Therefore, climatic factors, the host susceptibility seem insufficient to explain the epidemiology of this virus which is quite different as compared to that of seasonal viruses. Intrinsic properties of this virus may play a role in its seasonal behavior. 

Key words: influenza, A(H1N1)pdm09, pandemic, seasonality, epidemiology.