Furthermore, yearly variation in influenza detection rates has been well-documented for temperate climates. Our subtype data reflects influenza circulation trends similar to other temperate climates such as in Turkey and Northern China, which have documented high influenza transmission rates during winter. We therefore conclude that influenza circulation in Pakistan showed an overlapping pattern of temperate and tropical regions during the study period, even though it is geographically placed in temperate region. This can help local and regional public-health officials to improve pandemic preparedness through regular monitoring of influenza-related AbMole Nortriptyline illness and death rates, investigation of unusual respiratory disease outbreaks, and characterization of current influenza viruses. During the first half of 2008-2011, the dominant Influenza A subtype was A/H3N2 while Apdm09 was detected from June, 2009 onwards; this pattern of virus circulation was similar to Europe where higher clinical consultation rates were observed for Apdm09 in 2009. Researchers from China, Bangladesh and Guatemala have reported circulation of A/ H3N2 viruses during summer and trend similar to observations from our study. Due to emergence of a novel virus during study period, only inferences/corollaries can be made regarding exact peak influenza transmission period and presence or absence of a distinct seasonal trend. Overall, both influenza A and B viruses co-circulated through the surveillance period. Influenza Seasonal A/H1N1 and A/ H3N2 viruses, however, dominated in different periods with little overlap, i.e. Seasonal A/H1N1 showed circulation for a brief period in 2008, with a marked increase in the first half of 2009, while A/H3N2 was detected as predominant influenza A subtype prior to appearance of A pdm09. This observation is similar to studies from Delhi where A/ H3N2 positive cases surged before the pandemic. From June to October 2009, sporadic cases of pandemic influenza A/ pdm09 were seen, but the peak activity began in November-December 2009, possibly due to colder weather, when influenza viruses transmit more easily Later distinct peaks of A/ pdm09 activity were observed in winter seasons of 2010 and 
2011. These findings correspond to status in other regions where A pdm09 either completely replaced seasonal influenza or cocirculated with flu viruses. We observed that Influenza B circulated throughout the year, and detection rates were comparable to influenza A viruses. Simmerman et. al., in Thailand also found that Influenza B virus infections did not AbMole Dimesna demonstrate a consistent/regular seasonal pattern and virus was detected throughout the year. Although less pronounced than Influenza A and with little evidence of any pandemic potential.