Influenza is an acute infectious respiratory disease caused by influenza virus. It is included in the group of acute respiratory infections (ARI). It is periodically distributed in the form of epidemics and pandemics. At present, revealed more than 2000 variants of influenza viruses.

All age categories of people are susceptible to influenza. The source of infection is a sick person with a real or abortive form of the disease, excrete the virus with coughing, sneezing, etc. The patient is contagious from the first hours of the disease and to 3-5-day illness. Characterized by aerosol (inhalation of tiny droplets of saliva, mucus, which contain the flu virus) transmission mechanism and the extremely rapid expansion in the form of epidemics and pandemics. Epidemics of influenza is caused by serotype A, there are approximately every 2-3 years, caused by serotype B - every 4-6 years. Serotype C does not cause epidemics, but only sporadic outbreaks children and weak people have. In the form of epidemics this virus is more common in autumn and winter. Periodicity of epidemics is related to the frequent changes in the antigenic structure of the virus at his residence in the wild. High-risk groups are children, the elderly people, pregnant women, people with chronic diseases of the heart, lungs, as well as individuals with chronic renal failure.

The frequency of complications of the disease is relatively low, but in the case of their development, they may represent significant risk to the patient's health. Medium-heavy, heavy, and hyper-toxic form of influenza can cause serious complications. Causes of complications from influenza may be the following features of infection: influenza virus has a marked capillary-toxic effect, it is able to suppress the immune system, it also destroys tissue barriers, thus facilitating the aggression of tissue resident flora.


Facts about Seasonal Influenza - the Flu (2010). Retrieved 6 August 2010, from

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