ABSTRACT
Influenza type A [H1N1] virus is considered as a major concern for health care system all over the world and imposes a considerable burden on the community. The aim of this study was to evaluate the pattern of the disease in order to help health administrators in making decision for preventive measures. 297 definite cases of influenza A [H1N1] diagnosed from 15 July to 3 December 2009 in Fars province, south of Iran, were included in this study. Diagnosis was confirmed performing Real time-PCR. The patients' information including age, gender, occupation, nationality, education, residency area and history of overseas or domestic travel, history of contact with other influenza patients, and symptoms were collected and analyzed. The mean age at the time of diagnosis was 24.4 +/- 15.8 years. 76 [25.6%] patients were admitted in the hospitals, of whom, 11 cases died due to related influenza complications with Case Fatality Ratio [CFR] of 4.4%. The most common reported symptoms were fever, cough and sore throat. There were two waves in the disease incidence, one about 1 month after emergence of the disease and another around 1 month after school openings. The first peak was observed mainly among adults with a history of foreign travel while the second peak was mainly observed among school students. The magnitude of the epidemic was much higher when the disease was transmitted between students at the beginning of the school year. Considering the high incidence of H1N1 flu among the students [41%], vaccination programs and preventive measures should target this age group