Viral respiratory illnesses are responsible for large numbers of hospital admissions each year leading to substantial morbidity and mortality . The etiologic agents include a diverse group of viruses, such as influenza A which is responsible for intermittent pandemics . Reassortment of swine-origin and human strains led to circulating pH1N1 and a significant increase in hospital admissions during the 2009�C2010 influenza season. Timely identification of influenza is important as the administration of neuraminidase inhibitors may limit duration and severity of illness if given early . Rapid tests were found to be insensitive in the diagnosis of pH1N1 and unable to subtype the influenza virus. Molecular techniques replaced some of these tests, but the availability, expense and technical training limited widespread use of this technology . Therefore, many clinicians relied on clinical symptoms to diagnose influenza during the pandemic . The classic influenza-like illness , defined as fever and cough and/or sore throat, is often used to distinguish influenza from other respiratory viruses. However, other 1217486-61-7 viruses such as respiratory syncytial virus , rhinovirus, parainfluenza, adenovirus, metapneumovirus, and coronavirus, can cause a similar illness and circulate at the same time as influenza . Using ILI symptoms to diagnose influenza is neither sensitive nor specific . Other symptoms reported during the pandemic included gastrointestinal complaints , leukopenia , elevated aminotransferase levels , thrombocytopenia and other laboratory abnormalities . Although the clinical characteristics of pH1N1 infection may be similar to seasonal influenza , there is scant data in the literature comparing pH1N1 with other respiratory viruses. The inability to reliably diagnose a viral respiratory infection such as influenza A, often leads to coverage of possible bacterial etiologies . Overuse of antibiotics is not without consequence and can lead to complications including Clostridium difficile infection and high rates of resistance . Thus, an accurate diagnosis of influenza and other respiratory viral infections is important to avoid overuse of antibacterial agents and direct appropriate antiviral therapy.