Prevalence of Influenza A Viruses in Patients with Flu Symptoms Attending Mazandaran Provinces Health Centers, 2009-2013

Background and Influenza A is an infectious disease caused by RNA viruses of the influenza viruses. Influenza viruses spread around the world in seasonal epidemics. It is estimated to affect %5-%15 of the global population and causing about 250000 to 500000 yearly deaths, rising to millions in some pandemic years. The aim of this study was an epidemiological survey of influenza A virus in patients from Mazandaran province, in North of Iran during 2009-2013 using Real Time Polymerase Chain Reaction (RT-PCR). In this cross-sectional study, 2781 throat swabs from common cold samples were collected from patients attending Mazandaran province health centers. Influenza-RNA was extracted from samples using Pure LinkTM Viral RNA/DNA Kit. Identification of Influenza A viruses was done through RT-PCR using Super Script III Platinum, and Quantitative Real Time PCR System from Invitrogen with specific primers and probs. All samples were examined in the Influenza Laboratory affiliated with Mazandaran University of Medical Sciences. A total of 2781 patients including 1543 (%55.48) female and 1238 (%44.52) male were studied. We found 516 (%18.55) patients with influenza A virus of whom 281 (%55.46) were female and 235 (%45.54) were male. Most of these patients aged 21-30 years of old (%24.16). Influenza A virus was observed more (%31.61) in 2012. Influenza is one of the most prominent respiratory infections of human which causes severe morbidity and mortality. New influenza A viruses are constantly evolving by mutation or by re-assortment, since the influenza virus evolves rapidly, and new strains quickly replace the older ones. Due to the high mutation rate of the virus, a particular influenza vaccine usually confers protection for no more than few years. Identification of different types of viruses could be of great benefit in developing efficient vaccine.