Prevalence and Mortality of Influenza A (H1N1) Virus Among Patients With Acute Respiratory Infection in Southwest Iran

BACKGROUND: Khuzestan and other parts of Iran were involved with Influenza A (H1N1) pandemic in 2009. OBJECTIVES: The aim of this study was to describe the prevalence and mortality of H1N1 in Behbahan, a city in Khuzestan, Southwest of Iran. PATIENTS AND METHODS: The study population consisted of cases of influenza, hospitalized or referred to the city health centers. Diagnosis of H1N1 virus infection was based on rapid antigen testing (RT-PCR) of nasopharyngeal swabs. Data extracted from epidemiological survey forms, including demographic and clinical characteristics, laboratory results, risk factors and underlying diseases, medications, and treatment outcomes of patients were analyzed using SPSS 16 software by using Pearson chi-square test. RESULTS: From a total of 318 patients, 180 (56.6%) were male and 138 (43.4%) female. Total number of patients with positive H1N1 tests was 167 (52.5%) with a male: female ratio of 1.2:1. Of total 318 admitted patients, 173 (96.1%) males and 135 (97.8%) females recovered and 10 people (7 (3.9%) males and 3 (2.3%) females) died, among which, three had positive test results for H1N1. The most prevalent signs and symptoms were: fever in 308 (96%) patients, cough in 278 (86.6%), lower respiratory symptoms in 208 (64.8%), gastrointestinal symptoms in 90 (28%), respiratory distress in 45 (13.7), and flu-like symptoms in 65 (20.2%) patients. CONCLUSIONS: Prevalence rate of H1N1 infection in the study region was higher compared to other part of Iran; but, close to the expected rate. The H1N1-associated mortality rate was lower than the reported rates in Iran and other parts of the world.