Swine influenza in East and South East Asia: Which strategies to early detect emergences and cross-species transmissions?

Introduction Although the first three Flu pandemics were of avian origins, the most recent human pandemic H1N1 2009 has urged scientists to play more attention on the pivotal role of pigs in the process of emerging pandemic strain [1]. Considering the lack of data related to swine influenza virus (SIV), surveillance activities need to be improved very urgently all over the world [1], especially in East and South-East Asia, which produced around 516 millions of pigs (and 8.2 billions of poultry) in 2008, and represents more than the half of the world pig production (FAO). Pigs are the main reservoir of H1N1, H3N2 and H1N2 subtypes [2, 3]. The H1N1 and H3N2 emergence in swine occurred consecutively to cross-species transmission from birds or humans. The early detection of emerging/new swine influenza viruses should be based on a surveillance program of rare events. However, the surveillance modalities to detect the cross-species transmissions or to early detect new strains are still unclear. New methods or epidemiological tools must be developed and adapted. We propose alternative surveillance strategies to assess the risk of emergence and spreading of new strains.