What caused to this disease? = What caused this disease? What led to this disease? = OK

We can not always know what caused a disease. So you can account for multiple answers or possibilities within your question. What usually causes this? What may have brought this on? What are the types of things that may have lead to this? What do you think made this happen? What may have been the catalyst for this? What do you think we could have done to prevent this? What is usually the main factor that leads to this?

1. What caused this disease? 2. What led to this disease? Also you may also say: - what is the reason of this disease? -what caused this illness? ;)

Merhaba! What caused this disease or What led to this disease both work.