XMD17-109 influenza virus subtypes found in Bangladesh were similar to viruses that circulated around the globe during 2007-08. Even though our inpatient SARI samples were few, results suggest that influenza A/H3 virus caused more severe illness requiring hospitalizations. This higher virulence of influenza A/H3 over influenza A/H1 and influenza B is well established in studies from temperate regions. Kriging analyses suggested that in May 2008, the influenza possibly first introduced and then gradually to the north-west of Bangladesh. Influenza may be introduced to Chittagong or Dhaka through the air ports in both cities or maritime port in Chittagong or it may remain at low levels of circulation throughout the year and then flare up during the Gambogic-acid appropriate environmental conditions. However our surveillance did not found any evidence of year round circulation. In terms of spatial spread, it is possible that influenza spread rapidly between Chittagong and Dhaka because of the frequent travel between these two densely populated cities. These patterns of outward spread from dense population centers appear similar to the US, Brazil, and Japan. We ran the kriging analysis with data from the 2008 influenza season only. We expect to have more information on this with subsequent years of surveillance. Surveillance data suggest that May�CSeptember was the peak influenza season in Bangladesh which is offset from the influenza A season in poultry. The seasonality is consistent with reported seasonality of influenza infection from the populationbased surveillance in the Kamalapur neighborhood of Dhaka city, where the peak season was April to September during 2004�C2006. This time of the year is typically considered the rainy season in Bangladesh and during these two seasons of surveillance these months had higher rainfall as evident in the weather data from Bangladesh meteorological department. We found influenza positivity was concurrent with increased rainfall, temperature, and relative humidity consistent with recently published papers on influenza and climate.