--- title: "Waterborne diseases, transmission, prevention" subject: "Water Supply Engineering" chapter: 4 key: "semester_5/water_supply_engineering:water-borne-diseases" source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/water-borne-diseases site: BCT Engineering --- # Waterborne diseases, transmission, prevention Water Supply Engineering · Chapter 4: Quality of Water - Asked in: 2068 Baisakh (old course), 8 marks; 2067 Asar (old course); 2070 Chaitra (old course) (asked 3 times) - Video: [Waterborne diseases | Waterborne Pathogens | Public Health and Water Safety | Prevention & Control](https://www.youtube.com/watch?v=GlTdIRxpxAQ) — tiny Predators - 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-borne-diseases - Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-4 ## Question Describe the different types of water borne diseases transmitted through polluted water, their transmission mechanism and preventive measures/strategies. ## Short answer Water-borne diseases are infections from swallowing water contaminated with faeces, spread by the fecal-oral route. They include bacterial (cholera, typhoid), viral (hepatitis A, polio), protozoal (amoebiasis), helminthic, and chemical diseases. Prevention combines source protection, water treatment, sanitation, hygiene education, monitoring, vaccination, and chemical removal. ## Answer **Water-borne diseases** are infections caused by swallowing drinking water that contains pathogens from human or animal faeces. They spread by the fecal-oral route. #### Types, causes and transmission | Group | Diseases | Causative organism | |---|---|---| | Bacterial | Cholera, typhoid, paratyphoid, bacillary dysentery | Vibrio cholerae, Salmonella typhi, Shigella | | Viral | Hepatitis A and E, poliomyelitis, rotavirus diarrhoea | Hepatitis viruses, polio virus, rotavirus | | Protozoal | Amoebic dysentery, giardiasis, cryptosporidiosis | Entamoeba histolytica, Giardia, Cryptosporidium | | Helminthic | Ascariasis, hookworm infection | Ascaris, hookworm (eggs ingested or skin contact) | | Chemical | Arsenicosis, fluorosis, methaemoglobinaemia | Arsenic, fluoride, nitrate | #### Transmission mechanism An infected person passes the pathogen in stool. Through open defecation, leaking latrines, sewage, or surface run-off, the pathogen reaches rivers, wells and springs. Another person drinks the polluted water or eats food washed in it, gets infected and passes the pathogen again. Poor storage and handling at home can also contaminate water. In Nepal, outbreaks occur mainly during the monsoon. #### Preventive measures 1. Protect sources (fence springs, locate latrines more than 30 m away and downhill of wells). 2. Treat water: filtration, chlorination, boiling, SODIS, and safe storage in covered containers. 3. Provide sanitation: latrines, safe disposal of excreta and sewage treatment. 4. Hygiene education: handwashing with soap, food hygiene. 5. Regular water quality monitoring and testing for E. coli. 6. Vaccination (cholera, typhoid, hepatitis A) and oral rehydration therapy. 7. Remove arsenic and other chemicals by suitable treatment. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Water-borne diseases are caused by: A. too little water for washing B. pathogens in drinking water contaminated by faeces and swallowed C. insects breeding in water D. worms whose host lives in water Answer: B. They spread by the fecal-oral route through swallowed water. (Key point: Definition) 2. Giardiasis and amoebic dysentery are which group? A. Protozoal B. Bacterial C. Viral D. Chemical Answer: A. Giardia and Entamoeba histolytica are protozoa. (Key point: Classification) 3. Arsenicosis, fluorosis and methaemoglobinaemia are caused by: A. Salmonella B. Hepatitis viruses C. chemicals in water (arsenic, fluoride, nitrate) D. Hookworm Answer: C. These form the chemical group. (Key point: Chemical diseases) 4. In Nepal, outbreaks occur mainly in: A. winter, from frozen pipes B. summer droughts only C. spring festivals only D. the monsoon, when run-off carries faecal matter to sources Answer: D. Surface run-off and leaking latrines contaminate sources in the monsoon. (Key point: Transmission) 5. Latrines should be sited from wells at: A. more than 30 m and downhill of the well B. 5 m and uphill C. 10 m and uphill D. 30 m and uphill Answer: A. Downhill and far from the well prevents seepage to it. (Key point: Source protection) 6. Which is a preventive measure for water-borne diseases? A. Drain stagnant ponds only B. Treatment, safe storage, sanitation, hygiene education and vaccination C. Use bed nets only D. Increase water hardness Answer: B. Prevention combines source protection, treatment, sanitation and hygiene. 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