Influenza Virus: Evolution, Pandemics, and Modern Therapeutic Strategies

Influenza is a highly contagious respiratory illness caused by influenza viruses, which undergo continuous genetic evolution through antigenic drift and antigenic shift. These changes enable the emergence of seasonal epidemics and global pandemics that have had profound public health consequences throughout history. Influenza infection can range from mild upper respiratory symptoms to severe complications such as viral pneumonia and secondary bacterial infections.

This chapter discusses the classification, structure, evolution, and epidemiology of influenza viruses, along with the historical significance of major pandemics. It also reviews current preventive and therapeutic strategies, including vaccination and antiviral agents such as Oseltamivir and Zanamivir, emphasizing advances in modern influenza management.