Health Aspects of Water Supply Flashcards
(48 cards)
Two major qualities of water
Chemical (generally of lower importance; more time for remedial action)
MIcrobiological (outbreaks and epidemics; may have immediate adverse health effects)
Water related diseases are related to
impurities in water
*infectious/non-infectious
Disease transmitted through ingestion of contaminated water leading to diarrheal disease (cholera, typhoid fever, hepatitis, amoebiasis, cryptosporidiosis)
Water-borne diseases
Transmissions of water-borne diseases
Classical Water-borne infection cycle (demonstrates role of water contamination in transmission of water-borne diseases)
Fecal-oral route (exhibits the actors that contribute to transmission)
Water-borne infection cycle
Infected person > pathogens in excreta > contaminated water source > consumption of untreated water > susceptible person >
Ways by which individuals acquire disease
Ingestion of contaminated water
Hand-to-mouth habit
Why are children most vulnerable to fecal-oral route of transmission of water-borne diseases
- Consistent hand-to-mouth habit
2. Unwariness of what they are eating/drinking
why undertaking studies on the health impact of improvements in water supply quality is difficult
Infection have several and multiple routes
Prevention strategies for water-borne diseases
- Improve drinking wate quality through treatment
- Prevent use of unprotected sources (by discouraging use of springs, traditional wells, and open ponds)
- Proper disposal of human waste
Treatment of drinking water
• Coagulation • Flocculation • Sedimentation • Filtration • Disinfection → Must be ensured → Only process that directly addresses problems in microbiological quality
Low-risk water sources
→ Fully enclosed or protected (capped) and no surface water can run directly into it
→ People do not step into the water while collecting it
→ Latrines are located as far as possible, preferably not on higher ground
(Waters may leech by means of gravity)
→ Solid waste pits, animal excreta, and other pollution sources are located as far as possible
→ No stagnant water within 5 meters from the source
→ Wells: buckets are kept clean and off the ground, or a handpump is used
One of the principal ways of breaking the fecal-oral cycle
Safe disposal of feces
A critical barrier to disease transmission
Adequate sanitation
T or F: In water-washed diseases, transmission depends on quantity of water used rather than quality
True
Two main types of water-washed diseases
→ Infection of the eyes and skin (scabies, fungal infections, trachoma)
→ Infection carried by lice (louse-borne epidemic typhus)
What causes scabies?
Sarcoptes scabiei
common symptoms of scabies
intense itching and a pimple-like skin rash
• Usually spread by direct skin-skin contact with a person who has scabies
→ Scabies can spread rapidly under crowded conditions where close body contact is frequent
What causes trachoma?
*repeated infection = scarring
Chlamydia trachomatis (spread p to p through discharge from infected child's eyes) *blindness does not happen until adulthood
louse-born epidemic typhus is caused by
Rickettsia prowazekii
How is louse-borne epidemic typhus transmitted?
- Transmitted by body lice and cannot persist on people who regularly wash their clothes
- Can be due to limited access to water for regular bathing
Disease prevented by increasing water quantity used and improving accessibility and reliability of domestic water supply
Louse-born epidemic typhus
- Pathogen spends part of its life-cycle in water (e.g. snail or other aquatic animals)
- Parasitic worms require intermediate hosts to complete their life cycles
Water-based diseases
A water-based disease which is a major public health problem wherein miracidium enters snail in water
Schistosomiasis
How is schistosomiasis acquired?
when people come in contact with fresh water infested with larval forms (cercariae) of parasitic blood flukes, known as schistosomes
