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- 2068 Baisakh (old course) · 8 marks
- 2067 Asar (old course)
- 2070 Chaitra (old course)
Waterborne diseases, transmission, prevention
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.
Describe the different types of water borne diseases transmitted through polluted water, their transmission mechanism and preventive measures/strategies.
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
- Protect sources (fence springs, locate latrines more than 30 m away and downhill of wells).
- Treat water: filtration, chlorination, boiling, SODIS, and safe storage in covered containers.
- Provide sanitation: latrines, safe disposal of excreta and sewage treatment.
- Hygiene education: handwashing with soap, food hygiene.
- Regular water quality monitoring and testing for E. coli.
- Vaccination (cholera, typhoid, hepatitis A) and oral rehydration therapy.
- Remove arsenic and other chemicals by suitable treatment.
✓ Answer checked by Claude Opus 5.5 (high effort)
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