epidemiological, clinical and laboratory features of patients hospitalized with 2009 pandemic influenza in north of iran

background: the clinical manifestations and outcome of influenza infection differ between various patients in the world. the purpose of this study was to assess the clinical manifestations of patients with confirmed or suspected novel h1n1 flu infection in sari, north of iran. methods: from september 2009 to january 2010, the patients’ data were collected by retrospective chart review of medical records. laboratory confirmation included a positive rt–pcr (reverse transcriptase–polymerase-chain-reaction assay) from a nasal or pharyngeal swab sample. results: nearly 80% of established patients were in age group of 15-45 years. approximately 14.6% of female cases were pregnant there was no significant difference in clinical and laboratory characteristics of patients with confirmed h1n1 virus infection to total cases with influenza like illness (ili). thirty nine (95.1%) of the established patients had a combination of fever plus sore throat or cough. relative lymphopenia was reported in 36.6%. pneumonia was the most common complication. acute pericarditis evolved in one case and aseptic meningitis was reported in another. conclusion: precise collecting information of clinical manifestations, risk factors and other characteristics of flu, can help to the early infection detection, timely treatment of patients and proper preventive measurements.