Preventing Waterborne Diseases: Principles and Practices

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

  Classification:

• - 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)

Pathogens:
- 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)

Prevention:

• - 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