key responses – water water supply priorities in cholera / awd response session 3.1 wash cholera /...

Key responses – Water

Water supply priorities in cholera / AWD response

Session 3.1 WASH Cholera / AWD EP&R training

WASH cholera / AWD EP&R training

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Learning objectives

By the end of the session the participants will be able to• explain cholera / AWD transmission risks associated

with most common water sources and possible ways to intervene if sources are identified as contaminated

• describe priorities for provision of water in cholera / AWD response

• list most common field tests used for water quality analysis

• compare appropriateness of most common HHWT methods in cholera / AWD response

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Water sources

Consider that water might be contaminated with

vibrio cholerae where there is contact with:

• People who have cholera (remember they may be asymptomatic)

• Contaminated articles such as buckets, cups and clothes e.g. washing of patients beddings and clothes

• Faecal material e.g. when latrines are close to wells


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Surface waterWater source Risk of faecal

contamination

Rivers High to very high

Lake High to very high

Rainfall Low to high


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GroundwaterWater source Risk of faecal

contamination

Protected spring Nil or very low

Closed dug well Low

Open dug Well Medium to high

Borehole Nil or very low


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Other ways of accessing water

• Vendors• Water trucking• Standpipe


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Water trucking• Provides immediate supply

• Water source and quality

can be controlled

Considerations:

• Number of trucks to ensure

adequate water supply

• Cost very high

• Requires close monitoring

• Offloading to storage facility


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Importance of proper assessment • Have the different sources of contaminated water been

identified?• Can and have these sources been disinfected?• If not; are there any measures taken to ensure safe

water at household level, or have other water sources been provided?

• If wells are chlorinated is monitoring of residual chlorine levels taking place?

• Is there any system to provide safe water to high risk areas during an outbreak?

• Does population receive at least 15l of water /person /day?

• If chlorine tablets are provided at HH level does the population know how to use them properly?


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Water Quality vs. Quantity

You see a card in 3 corners of this room

Walk around and decide which would be

your priority for water in cholera / AWD

response


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Blocking of transmission of cholera by water interventions

Cholera (Faeces

and vomit)

Fluids (water

sources)

Soil

Hands

FoodNew Host

Sanitation

Hand washing

Water Quantity

Water Quality


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Transmission routes and prevention strategies Transmission

routeInfection Prevention strategies

Water-borne Diarrhoeas and dysenteries, including choleraHepatitis A

Improve quality of drinking water usedPrevent casual use of unprotected sourcesImprove sanitation Improve hygiene

Water-washed

Infectious skin and eye diseasesLouse-borne typhus

Increased quantity of water usedImproved accessibility & reliability of supplyImprove hygiene

Water-based SchistosomiasisGuinea worm

Reduce need for contact with infected waterControl snail populationsReduce contamination of surface waters

Water-related insect vector

FilariasisMalariaRiver blindnessYellow fever

Improve surface water management Destroy breeding sites of insects Reduce need to visit breeding sites Use mosquito netting Source Cairncross & Feacham (1999, 2nd edn)

Environmental Health Engineering

in the Tropics


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Water quantity

Source The Sphere Project (2004)


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Water Quality

•Physical E.g. turbidity, colour•ChemicalE.g. iron, arsenic•Microbiological and biological

E.g. bacteria, protozoa


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During a cholera outbreak the most significant parameter to follow up are the bacteriological parameter


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Sphere key indictors for water quality

• Turbidity (cloudiness index) - less than 5 NTU

• Faecal coliform - 0 FC/ 100 ml

• Residual chlorine (if water is disinfected) – 0.5 mg/l (for piped systems and during outbreaks)


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Turbidity

• Refers to clarity of water i.e. the greater the amount of total suspended solids the higher the turbidity

• Affects disinfection: high turbidity protects micro-organisms from the action of disinfectants


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How to test turbidity ?

• Turbidity tube

(most common

field method)

• Secchi disk

• Electronic devises


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Microbiological and Biological Water Quality

• E-coli is used as an indicator for faecal contamination

• Testing for E-coli is not always required if the water is going to be treated anyway

• SPHERE key indicator Faecal coliform - 0 FC/ 100 ml

Recommendation is to treat (chlorinate) all

drinking water and water used for cooking

during a cholera outbreak


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How to test microbiological quality in the field

• DelAqua kit• Wagtech

• H2S

• No field tests

to detect V.C

from water source


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Use of DelAgua

4 – 6 hours

16hrs incubation

ON

source Medair Madagascar


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• An on-site testing method for microbial quality of drinking water

• Faeces contain a high concentration of hydrogen sulphide (H2S) producing bacteria so water contaminated with faeces will react

Hydrogen Sulphide (H2S) tests

Result:

Yes / no (presence/ absence)

Turns black when it comes in

contact with hydrogen

sulphide

Eric Fewster, BushProof


Common Household Water Treatment Methods

• Chemical e.g. Chlorination• UV disinfection• Boiling• Filtration

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0 10 20 30 40 50

% reduction in diarrhoea

Water Supply (quality& quantity)

Water Quality Source

Water QualityHousehold

Sanitation

Hand washing

Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis, Fewtrell et al

(2005)

Data leads to some controversy, partly of the difficulty of splitting impacts of interventions. For example:

* Hand-washing is not possible without a water supply, so ‘hand-washing’ is in fact ‘water supply and hand-washing’

** Water quality at household will also have involved some hygiene promotion when setting up the household water treatment processes

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Let’s think of appropriateness of different HHWT methods in a cholera / AWD outbreak response

Filtering Boiling

UV disinfection

Chemical

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Water storage

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Water storage

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Learning objectives

By the end of the session the participants will be

able to• explain cholera / AWD transmission risks associated

with most common water sources and possible ways to intervene if sources are identified as contaminated

• describe priorities for provision of water in cholera / AWD response

• list most common field tests used for water quality analysis

• compare appropriateness of most common HHWT methods in cholera / AWD response

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key responses – water water supply priorities in cholera / awd response session 3.1 wash cholera /...

Documents

hygiene water

safe water

provision of water

common water sources

cholera awd response

water quality analysis

quality of drinking

water person day