What are the immediate and contributory causes of diseases? Explain it with the example of a child suffering from diarrhoea.

Diarrhoea is caused by viral or bacterial infection. So viral infection is immediate cause of disease. 

Even though a virus can be the immediate cause of a disease, other associated causes might allow the entry of the virus into the body. These causes are known as contributory causes.  Like Unhealthy condition: Infectious agents like virus and bacteria enter the body through contaminated food or water. Thus, the consumption of contaminated food or water can be another cause of disease.