**2. Influenza pathogenesis**

The pathogenesis of influenza virus infection is associated with two general processes in the human body: (i) local lung damage due to viral replication in the columnar ciliary epithelium of bronchi and bronchioles, which leads to progressive damage of the alveolar cells, bronchopneumonia (viral or combined viral-bacterial), massive bronchitis (including bronchiolitis), and the like, as the major causes of death [4]; (ii) a dramatic inflammatory burst that induces among other processes an increase in reactive oxygen species generation, causing extensive damage in cellular membranes, predominantly in the small vessels, arterioles, and capillaries [5–8]. In addition, extrapulmonary complications affect many organs and tissues, such as heart, brain, middle ear, liver, and endocrines, and even stomach and kidneys, though that is rare [9–14].
