In the following, which water pollutant is a source of the water-borne disease Cholera ?

Question

Accepted Answer

The correct option is (2):
Sewage is the most significant and direct source of the water-borne disease Cholera because it is the main vehicle for the causative agent, the bacterium *Vibrio cholerae*. Cholera is transmitted primarily through the fecal-oral route, which means the disease spreads when an individual consumes food or water contaminated with the feces of an infected person. Inadequate or non-existent sewage treatment facilities lead to the discharge of raw municipal wastewater, which contains human feces, directly into rivers, lakes, or groundwater used for drinking. This fecal contamination introduces the *Vibrio cholerae* bacteria into the public water supply, leading to rapid and widespread outbreaks, especially in densely populated areas with poor sanitation.

The incorrect option is (1):
Animal waste, such as manure, is a known water pollutant that can carry various pathogens, including bacteria, viruses, and parasites. However, Cholera is caused by *Vibrio cholerae*, which is considered a human-specific pathogen, meaning it is spread predominantly from human feces to humans. While animal waste can certainly contaminate water and cause other diseases, it is not the primary or most direct source of the *Vibrio cholerae* bacterium that drives human cholera epidemics.

The incorrect option is (3):
Mercury is a heavy metal, making it a type of inorganic chemical pollutant, typically entering the water supply from industrial effluent or mining operations. This pollutant poses a serious health risk, as it is a neurotoxin that bioaccumulates in the food chain and can cause severe neurological damage upon ingestion. Since cholera is a disease caused by a living bacterium, *Vibrio cholerae*, the chemical substance Mercury cannot be the source of this specific biological infection.

The incorrect option is (4):
Fertilizers are classified as nutrient pollutants, containing high levels of compounds like nitrates and phosphates. Their primary negative impact on water quality is triggering eutrophication, which is the excessive growth of algae that starves the water body of oxygen. While high nitrate levels in drinking water can cause methemoglobinemia ('blue baby syndrome') in infants, fertilizers themselves do not contain or transmit the *Vibrio cholerae* bacteria, and thus are not the source of a cholera outbreak.