theory of disease causation

https://www.ted.com/talks/rishi_manchanda_what_makes_us_get_sick_look_upstream?language=en

What are your thoughts about Disease Causation?  Explain your position on this subject through the use of peer reviewed scholarly sources from MedLine, Ebsco, Proquest, and/or Google Scholar.  Use the eCollin Library available at your fingertips.  You must provide at least three additional sources to the video.  

Please write a 300 to 500 word essay adhering to APA 7th Edition formatting guidelines