Preventing Waterborne Diseases: Principles and Practices

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2. The transportable diseases potentially spread by drinking water, prevention them; principles and practice of disinfection of the water

Water-Associated Diseases

  • - Most of the disease agents contaminating water are biological and communicable and come from animal and human feces

  • - They include bacteria, viruses, protozoa, and helminths and are ingested with water


  • - Waterborne diseases: arise from the contamination of water by human or animal feces or urine infected by pathogenic bacteria or viruses – direct transmission into organism

  • - Water–based diseases: water provides the habitat for intermediate host organism, some parasites pass part of their life cycle →helminthic diseases in people

  • - Water–related diseases: water may provide a habitat for water–related insect vectors of diseases (e.g. mosquitoes)

  • - Water–dispersed infections: their agents can proliferate in freshwater and enter the human body through the respiratory tract (some freshwater amoebas → warm water amoebas → fatal meningitis or pneumonia, etc...

    PathogenEnteric fevers (typhoid and para-thyphoid)





Diarrhoeal diseases (salmonellosis, shigellosis, campylobacteriosis, E. coli)

Rotavirus Poliomyelitis

Amoebiasis Trypanosomiasis (water-related) Malaria (water-related) Dengue Fever (water-related)

Schistosomiasis Guinea worm

- Protozoal:

  • Entamoeba histolytica – from sewage, non-treated drinking water

  • Cryptosporidium parvum – from water filters and membranes that cannot be disinfected

  • Giardia lamblia – untreated water, poor disinfection, pipe breaks, leaks, groundwater contamination

    - Parasitic:

  • Schistosomiasis – freshwater contaminated

  • Taenia and Enterobiasis – drinking water contaminated with eggs

  • Echinococcosis and Ascariasis – drinking water contaminated with feces

    - Bacterial:

  • Clostridium botulinum, Campylobacter jejuni, Vibrio cholera, E. coli – gastroenteritis with diarrhea with mucus, abdominal pain, and vomiting

  • Dysentery (Shigella, Salmonella) – bloody diarrhea

  • Legionella – Pontiac fever or atypical pneumonia

    - Viral:

  • Gastroenteritis – astrovirus, norovirus, rotavirus, adenovirus

  • HAV, HEV

  • Poliovirus

Trachoma (washing)


  • - Nails should be cut short

  • - Only filtered/branded bottle water should be consumed

  • - Wash hands with soap and water before consuming food

  • - If there’s no water purification system, water should be drunk after boiling and cooling

  • - Consult a doctor as soon as symptoms start, drink oral-rehydration solution (ORS)

  • - Check the expiry date of all packed vegetables and drinks before consumption

  • - Drinking water container should be washed every day

  • - Only warm and freshly cooked food should be consumed

  • - Avoid the consumption of food and drinks from roadside vendors

  • - Avoid half-cooked or raw food

  • - Avoid sharing utensils while consuming food

  • - Do not expose food and beverages to flies

    Water disinfection:

- Definition: removal, deactivation, or killing of pathogenic microorganisms resulting in the termination of growth and reproduction • ≠ Sterilization, where all present microorganisms are killed including their spores (both harmful and harmless)

- Types:

  • Chemical (e.g. chlorine – Cl2, chlorine dioxide ClO2, ozone – O3, iodine – I, metals, alcohols, soaps and detergents, hydrogen peroxide, acids or bases)

  • Physical (e.g: UV light, electronic radiation, gamma rays, ultrasound, heat)

    Safe water requires a combination of the following water purification steps:

  • - Oxidation – chemical oxidants remove both organic and inorganic compounds

  • - Coagulation – facilitates the removal of suspended solids and colloid particles

  • - Settling

  • - Disinfection

  • - Filtration

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