Causative

Explanatory SectionDr. Zhang Wei, Chief Physician of the Pulmonary Diseases Department at the Affiliated Hospital of Shandong University of Traditional Chinese Medicine:Influenza A differs from common colds in terms of causative virus type, clinical symptoms, and contagiousness; mild cases can recover on their own, while severe ones require special attention.What is influenza A? Influenza A, also known as Type A flu, is caused by influenza viruses. There are four types of influenza viruses: A, B, C, and D. Among these, Type A (mainly subtypes H1N1 and H3N2) and Type B (Yamagata and Victoria lineages) are more widespread in human populations. The incubation period for H1N1 influenza is generally longer than that of regular influenza and avian influenza, typically ranging from 1 to 7 days.How does it spread? The primary transmission route for influenza A is via respiratory droplets. It can also spread through direct or indirect contact with respiratory secretions, bodily fluids, and objects contaminated with the virus. Children are the main infected population, with no significant gender difference. They acquire immunity to the same strain within a short time after infection but are prone to recurrent episodes.How is it diagnosed? After being infected with influenza A, patients may experience…