Question

Sewage contamination of water is indicated by cysts of:

• A. Escherichia
• B. Entamoeba
• C. Pseudomonas
• D. Leishmania

Answer 1

The correct option is B

Entamoeba

The correct option is option B.

Explanation of the correct option:

1. It is an invasive pathogenic protozoan.
2. It has two stages in its life cycle namely- trophozoite and cyst.
3. The cyst is excreted by faeces and can survive for several weeks.
4. Hence the presence of cysts in freshwater is an indication of sewage contamination.

Explanation of the incorrect options:

Option A:

1. It indicates fecal contamination in fresh water.
2. As these organisms are present in the intestines of humans hence they are used to indicate fecal contamination.

Option C:

1. It is a gram-negative gamma proteobacterium.
2. It is mostly found in the hospital environment.
3. It causes nosocomial infection in hospital patients.

Option D:

1. It is a parasitic protozoan.
2. It causes leishmaniasis.

Final answer: Sewage contamination of water is indicated by cysts of Entamoeba.