Influenza A virus and related secondary bacterial infections

Influenza infection is considered to be a serious respiratory disease in human. Annually, epidemics or even pandemics give rise to the frequent antigenetic variations of virus surface receptors, throughout the world. Bacterial infections followed by influenza are the biggest medical concerns associated with elevated mortality rates. These high morbidity and mortality rates, have become a priority in terms of health. Likewise, economic aspects of the issue have special importance also. In the present study, several articles have been investigated with regards to main key words including influenza A, secondary bacterial infections and pandemics. Then, attempts have been made to summarize the information in concise figures (was graphically visualized) and tables in addition to main literature. Until this date, a number of influenza pandemics have taken place with varying morbidity and mortality rates because of secondary bacterial infections followed by influenza. However, the 1918 pandemic had the highest death rate recorded. According to investigative studies, Streptococcus pneumoniae and Staphylococcus aureus are the most common isolated bacteria in patients with secondary infections. Other bacteria, such as Haemophilus influenza, Streptococcus pyogenes, and to a lesser degree Legionella spp., are involved in these infections as well. Currently, it is known that various protease enzymes intensify the influenza virus infectivity. Another important aspect of influenza occurs in the Hajj pilgrimage season and many vaccines have been made to deal with its consequences. These vaccines decrement the mortality rate, however, some have minor side effects.