Influenza

Influenza is an acute disease that mainly causes respiratory symptoms and, more rarely, gastrointestinal symptoms. It usually causes mild illness in the general
population, but rarely severe illness in specific groups of the population. 

The outbreak of the disease usually begins in the 45th week of the year, which coincides with the beginning of October, and ends at the end of April.

Influenza viruses are RNA viruses of the Orthomyxoviridae family (Orthomyxoviridae). The genome consists of eight separate RNA strands. The virus is surrounded by a capsid consisting mainly of viral proteins (hemagglutinin and neuraminidase).