الفهرس 
Introduction
Historical BackgroundOnly 14 pages are availabe for public view
 |  | from | 143 |  |  |
| | | from | 143 | | |
Abstract
Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals .The word Influenza comes from the Italian language meaning”influence” and refers to the cause of the disease. In virus classification influenza viruses are RNA viruses that make up three of the five genera of the family Orthomyxoviridae: Influenza virus A ,Influenza virus B and Influenza virus C. The type A viruses are the most virulent human pathogens among the three influenza types and cause the most severe disease. The influenza A virus can be subdivided into different serotypes based on the antibody response to these viruses. Symptoms of influenza may include fever, cough , nasal congestion ,body aches, especially joints and throat ,fatigue ,headache and irritated, watering eyes .In children, gastrointestinal symptoms such as diarrhea and abdominal pain may be severe especially with influenza B. The most frequent complication of influenza is secondary bacterial pneumonia, while primary influenza pneumonia the most severe. In addition, mixed viral and bacterial pneumonia frequently occurs during outbreaks. Influenza may exacerbate heart or lung diseases or other chronic conditions.