With respect to Water Pollution, Causes and Effects of Pathogenic Organisms

Causes:
These pathogenic organisms are naturally present in water sources. Also these get contaminated in water due human activities such as disposal of kitchen waste, human and animal excrete near or in the water sources.

Effects:
The majority of waterborne diseases arise as a result of the contamination of water used for drinking with human or animal faeces. The pathogens contained in the faeces of a diseased human or animal are distributed within the water body and may be ingested by others, either directly by drinking or by consuming crops irrigated or washed with the same water. In addition to sewage, pathogens that infect humans have been identified in livestock, fowl, wildlife pets and even fish in contaminated water. This highlights the range of mobility that exists for enteric pathogens and explains the level of concern over faecal pollution.