Multiple choice general knowledge Name the causative agent for Swine flu? H1N1 H1S1 culex virus none Reveal answer Fill a bubble to check yourself A Correct answer Explanation Swine flu is caused by the H1N1 influenza virus (Influenza A virus subtype H1N1). This specific strain was responsible for the 2009 swine flu pandemic. H1N1 is the correct and internationally recognized designation for this virus.