---
title: "Water-based diseases"
subject: "Water Supply Engineering"
chapter: 4
key: "semester_5/water_supply_engineering:water-based-diseases-define"
source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/water-based-diseases-define
site: BCT Engineering
---

# Water-based diseases

Water Supply Engineering · Chapter 4: Quality of Water

- Asked in: 2081 Baisakh, 2 marks; 2080 Baisakh, 2 marks (asked 2 times)
- Video: [57. Water borne diseases || Water supply Engineering](https://www.youtube.com/watch?v=SQYACBLQetc) — NITIANS ACADEMY
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/water_supply_engineering/water-based-diseases-define
- Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-4

## Question

Define water-based diseases (with examples).

## Short answer

Water-based diseases are caused by parasitic worms that spend part of their life cycle in an aquatic intermediate host, such as snails or Cyclops. Examples include schistosomiasis (snail host), guinea worm disease (Cyclops), and liver fluke infections. Control involves avoiding infested water, filtering/treating water, and snail control.

## Answer

**Water-based diseases** are diseases caused by pathogens (usually parasitic worms) that spend a part of their life cycle in a water-dwelling animal (an intermediate host such as a snail or crustacean). A person is infected by contact with, or by swallowing, the infected water.

#### Examples
| Disease | Cause | Intermediate host | Transmission |
|---|---|---|---|
| Schistosomiasis (bilharzia) | Schistosoma worms | Freshwater snail | Larvae penetrate skin when bathing or wading |
| Guinea worm disease (dracunculiasis) | Dracunculus medinensis | Cyclops (water flea) | Drinking water with infected Cyclops |
| Fascioliasis, clonorchiasis | Liver flukes | Snails, fish, water plants | Eating raw water plants or fish |

Control: avoid contact with infested water, filter or treat drinking water, control snails, and provide safe piped or hand-pump water.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Water-based diseases involve pathogens that:
   A. spend part of their life cycle in a water-dwelling intermediate host
   B. are carried by mosquitoes only
   C. spread through lack of washing water
   D. come only from chemical pollutants
   Answer: A. The host may be a snail or Cyclops. (Key point: Definition)

2. Schistosomiasis is transmitted when:
   A. Cyclops are swallowed
   B. larvae from freshwater snails penetrate the skin during bathing or wading
   C. mosquitoes bite
   D. hands are unwashed
   Answer: B. The snail is the intermediate host. (Key point: Schistosomiasis)

3. The intermediate host of guinea worm is:
   A. Freshwater snail
   B. Anopheles mosquito
   C. Cyclops (water flea)
   D. Housefly
   Answer: C. People are infected by drinking water containing infected Cyclops. (Key point: Guinea worm)

## Related in Water Supply Engineering

- [Water washed diseases and prevention](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Awater-washed-diseases) — Water Supply Engineering, chapter 4, asked 2×
- [Water vector diseases](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Awater-vector-disease) — Water Supply Engineering, chapter 4
- [Waterborne diseases, transmission, prevention](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Awater-borne-diseases) — Water Supply Engineering, chapter 4, asked 3×