Established population based influenza surveillance in Palmitic-acid children younger than five years old in Kamalapur, a low income urban neighborhood in the capital city, Dhaka. After two years of surveillance investigators reported that 14% of children with acute respiratory infections had respiratory isolates that tested positive for influenza. The surveillance suggested that influenza season occurred during April through September. This surveillance system also identified the one human case of infection with influenza in Bangladesh. Based on the knowledge gained from the Kamalapur study, investigators from ICDDR, the Institute of Epidemiology, Disease Control and Research of the Government of Bangladesh and Centers for Disease Control and Prevention, United States, collaborated to broaden influenza surveillance in this country. The primary objective was to understand the epidemiology and seasonality of influenza strains in Bangladesh from all areas and all age groups in the country. Aims included quantifying the prevalence of influenza infections among persons seeking care at the outpatient department of these hospitals, identifying circulating influenza virus strains, exploring seasonality, and characterizing clinical manifestation of influenza. In addition to these we also intended to identify novel influenza viruses among hospitalized case-patients. To determine the number of influenza positive ILI case-patients conducted active surveillance in outpatient Epifriedelanol departments affiliated with each hospital on two consecutive days each month. In addition, to identify novel influenza virus, we collected specimens from SARI case-patients from the hospitals�� inpatient wards during those two days. After obtaining signed informed consent, the surveillance physicians collected throat and nasal swab from patients of all age groups visiting outpatient departments of those hospitals with influenza like illness, defined as subjective fever and. We also collected samples from the patients admitted in the medicine and pediatrics inpatient departments who met the case definition of severe acute respiratory illness, defined as fever and and.