(d) Influenza
Influenza is a viral infection that attacks your respiratory system. It is caused by the influenza virus or flu virus.
Influenza spreads through direct contact, air/droplet transmission or fomite borne.
A viral disease or a viral infection occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles attach to and enter susceptible cells.
Example: Dengue, AIDS, Influenza, Polio, Measles etc.