Define immediate cause and contributory cause.

The immediate cause of a disease is the primary factor causing a disease, ie organisms like bacteria, viruses.
Contributory causes are factors, which do not cause the disease themselves but provide conditions for the disease to occur. It includes

(i) poor health due to lack of nourishment.
(ii)poor hygienic condition, ie lack of freshwater, unhealthy food.
(iii)genetic differences may also cause.
Eg: A virus causing diarrhea is the immediate cause. Contaminated drinking water and lack of resistance due to under-nourishment are the contributory causes.