نوپديدي و جهانگيري آنفلوآنزاي A H1N1 سال 2009

Emerging and Pandemic of Influenza A(H1N1)

Influenza is one of the known viral infectious diseases, which has killed millions of peoples during pandemics, epidemics and sporadic forms. One of the most remarkable features of influenza virus is the frequency of changes in antigenicity. Alteration of the antigen structure of the virus leads to infection with variants to which little or no resistance is present in the population at risk. Pandemics of influenza type A, result from the emergence of a new virus which the population contains no or limited immunity to it. The interval between pandemics is 10-30 years. But Influenza virus has been causing epidemics of febrile respiratory disease every 1 to 3 years. Pandemic (H1N1) 2009 is a new virus that has not circulated among human population before. This virus is different from previous or current human seasonal influenza viruses. Influenza type A(H1N1) virus is transmitted by inhaling infected droplets expelled by coughing or sneezing or by touching contaminated hands or surfaces as the same as the normal seasonal flu. The symptoms and signs of A(H1N1) influenza are as similar as seasonal influenza and include fever, coughing, runny nose and sore throat. Some people have also reported, nausea, vomiting and diarrhea. People with existing cardiovascular disease, respiratory disease, diabetes and cancer are at higher risk of serious complications. Asthma and other respiratory disease are other underlying conditions associated with severe disease. Pregnant women are at higher risk for more severe disease and obesity may be another risk factor for severe disease. To prevent spread, people should cover their mouth and nose when coughing or sneezing, stay at home when they are unwell, clean their hands regularly, and avoid crowded areas if possible