What are water-related diseases? Waterrelated diseases and their control – options for integration Prof. Thor Axel Stenström, SARChI, Durban University of Technology, Durban, South Africa.

International Seminar on Integrated Water-Related Disease Control 12-14 May 2014, Norwegian University of Life Sciences (NMBU), Ås, Norway

Water-related diseases • Waterborne diseases, i e cholera, typhoid, and dysentery, are caused by faecal-oral transmission (drinking water, recreational water) containing infectious microorganisms, mainly from human or animal waste. • Water-washed diseases, such as skin and eye infections, are caused by lack of clean water for washing. • Water-based diseases, such as schistosomiasis, are spread by organisms that develop in water (intermediate hosts) and then become human parasites (skin penetration, ingestion). They are spread by contaminated water and by eating insufficiently cooked fish. • Water-related insect vectors, such as mosquitoes, breed in or near water and spread diseases, including dengue and malaria. This category is not directly related to water supply or quality. • Additional: • Aerosol related (i e Legionella, endotoxins) • Water – food related (i e irrigation of crops, faecal-oral) • Nosocomial.

Water-related diseases (WHO) • Water, sanitation and hygiene have important impacts on both health and disease. • Water-related diseases include: • • • • •

those due to micro-organisms and chemicals in water people drink; diseases like schistosomiasis which have part of their lifecycle in water; diseases like malaria with water-related vectors; drowning and some injuries; and others such as legionellosis carried by aerosols containing certain micro-organisms. • Water also contributes to health, for example through hygiene.

Relationship Between Exposure, Level of Protection and Microbial Risk

= Confidence Region or Interval

Risk 

Exposure  Quantity Multiple Barriers Level of Technological /Handling Control

Risk reduction strategies WHO’s multiple barrier approach from “Farm to Fork”

Wastewater generation

Wastewater treatment

Farmer/ Consumer Producer

Safe Safe Irrigation produce Practices

Traders/ Retailers

Hygienic Handling Practices

Street food kitchens

Safe food washing and preparation

Policy recognition, safer farm land, tenure security, market incentives, safe-food labelling,…

Consumer Awareness … creation to create demand for safe produce

DALYs as unit measures for health • Conceptually simple: – health loss = N x D x S • N = number of affected persons • D = duration of adverse health effect • S = measure for severity of the effect

• Disability Adjusted Life Years – mortality: years of life lost (YLL) – morbidity: years lived with disability (YLD) – DALY = YLL + YLD

Acute and Chronic Outcomes Associated with Microbial Infections (previous lecture) Microbe Campylobacter E. coli O157:H7 Helicobacter Sal., Shig., Yer. Coxsackie B3 Giardia Toxoplasma

Acute Outcomes Diarrhea Diarrhea Gastritis Diarrhea Encephalitis, etc. Diarrhea Newborn Syndrome

Chronic Outcomes Guillain-Barre Syndrome Hemolytic Uremic Syn. Ulcers & Stomach Cancer Reactive arthritis Myocarditis & diabetes Failure to thrive; joint pain Mental retardation, dementia, seizures

Norway

Global Burden of Diseases (Country perspective)

Rank and Disease YLL (1990) x 1000

YLL (2010) x 1000

Change (%)

1 Ischemic heart disease 2 Stroke

180 (25.1%)

86 (15.0%)

-54

67 (9.4%)

39 (6.9%)

-42

3 Lung cancer

31 (4.4%)

36 (6.4%)

27

4 Lower respiratory infections

29 (4.0%)

17 (3.0%) (rank 7)

-45

5 Self-harm

28 (3.9%)

22 (3.9%) (rank 6)

-22

Colombia Global Burden of Diseases (Country perspective)

Rank and Disease

YLL (1990) x 1000

YLL (2010) x 1000

Change (%)

1 Interpersonal violence 2 Lower respiratory infections

1,404 (19.8%)

1,118 (16.0%)

-23

476 (6.7%)

328 (4.7%) (Rank 5)

-32

3 Ischemic heart disease

461 (6.5%)

554 (7.9%) (Rank 2) 3 Now HIV/AIDS 456 (6.5%)

20 2,164 up

4 Preterm birth complications

393 (5.6%)

289 (4.1%) (Rank 8) 4 Now Road injury 342 (4.9%)

-27 11

5 Diarrheal diseases

371 (5.2%)

105 (1.5%) (Rank 16)

-72

South Africa Global Burden of Diseases (Country perspective)

Rank and Disease

YLL (1990) x 1000

YLL (2010) x 1000

Change (%)

1 Diarrheal diseases

1,413 (12.2%)

1,138 (4.9%) (Rank 2) 1 Now HIV/AIDS11,201 (48%)

-20 4,962

2 Lower respiratory infections

1,083 (9.3%)

873 (3.7%) (Rank 4)

-20

3 Tuberculosis 4 Interpersonal violence 5 Preterm birth complications

668 (5.8%) 692 (6.0%)

760 (3.3%) (Rank 5) 1,018 (4.4%) (Rank 3)

15 32

524 (4.5%)

500 (2.1%)

-4

Surveillance systems • Public health surveillance has been defined as "the ongoing and systematic collection, analysis and interpretation of health data to describe and monitor a health event" (Klaucke, 1992). • Information from surveillance systems is used to plan public health interventions and monitor whether they have been effective in improving public health.

WHAT IS A WSP?

 A way to ensure safe drinking-water by:  Knowing the system thoroughly  Identifying where and how problems could arise  Multibarrier approach - Putting barriers and management systems in place to stop the problems before they happen  Making sure all parts of the system work properly

 A comprehensive risk assessment and risk management approach that encompasses all steps in water supply from catchment to consumer  Fits within a framework for safe drinking-water

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Prepare WSP Describe water supply system

WSP DOCUMENTATION

Prioritize risks

Determine existing control measures

Identify additional or improved control measures

Control hazards Implement and manage control measures Define monitoring of control measures

Prepare management procedures

Verify and audit WSP

Improvement and upgrade plan

Identify hazards

PLANNED PERIODIC REVIEW

System assessment

Water Safety Plan

OVERVIEW OF WATER SAFETY PLANS

incident

Revise WSP following incident (Module 11)

Assemble team (Module 1)

Identify the hazards & assess the risks (Module 3)

Plan & carry out periodic WSP review (Module 10) Preparation System assessment

Develop supporting programmes (Module 9)

Describe the water supply system (Module 2)

Monitoring Management & communication Feedback

Prepare management procedures (Module 8) Verify the effectiveness of the WSP (Module 7)

Determine & validate control measures, reassess & prioritize risks (Module 4) Develop, implement & maintain an improvement plan (Module 5)

Define monitoring of control measures (Module 6)

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LINKING CATCHMENT MANAGEMENT AND WSP Identify key catchment stakeholders Verify effectiveness of catchment controls Promote catchment risk mitigate measures

Develop catchment warning and response procedures

Develop catchment partnerships Flood and drought information is needed Implement risk based raw water monitoring

Map and characterise catchments

Identify hazards and hazardous activities

Assess risks which could compromise treated water quality

Balance between need for enhanced treatment and likely effectiveness of catchment controls Assess need for improved treatment to reduce risk

Infectious Disease Transmission Model at the Population Level: Dynamic Model • Risk estimation depends on transmission dynamics and exposure pathways. Example: Water

Model Development: Household-level Model of Pathogen Transmission from Water

Poor public health (high morbidity and mortality)

Dengue fever

Diarrhoeal diseases Effect

Adverse impacts Poor of temperature immunity & & rainfall health status

High mosquito density

Cause

Nutrients for mosquito larvae

Contaminated water (pathogen load)

Non-functioning community participation

Poor solid waste disposal

Poor mosquito control

Open sewers

Lack of political will & initiative

Inadequate sanitation and waste management

Open defecation

Animal feaces present

Poor household water management

Poor storage practices and bad containers

Economical constraints

Poor water collection practices

Poor water transport practices

Poor immunity & health status

Poor hygiene (e.g. hand washing)

Poor domestic water use practices

Lack of knowledge, poor education in community

Dirty water breeding mosquitoes − Culex spp: vectors of FILARIASIS

Risk prioritization Semi-quantitative risk matrixes • Risk is calculated by multiplying ‘Likelihood’ by ‘Severity’ • Likelihood or frequency: – How often or likely will a hazardous event occur?

• Severity or consequence: – What will be the consequences for public health or the consumer acceptance?

Risk prioritization

LIKELYHOOD CATEGORIES: A Daily to weekly B Monthly to quarterly (seasonally) C Yearly or above RISK CATEGORIES: H High M L

Moderate Low

LIKELYHOOD

SEVERITY / CONSEQUENCES SEVERITY CATEGORIES: RISK MATRIX I No impact I (1) II (2) III (3) II Impact on aesthetic quality (i.e. consumer acceptance) OR quantity M (3) H (6) H (9) A (3) III Regulatory impact OR impact on consumer health B (2)

L (2)

M (4)

H (6)

C (1)

L (1)

L (2)

M (3)

Urgent management attention needed (= immidiate action) Management attention needed Routine procedures