Paul R Hunter School of Medicine, Health Policy and Practice University of East Anglia
Water associated diseases Water-borne diseases Water-washed diseases Water-based diseases Water-related diseases? Water travel diseases
Caused by the ingestion of water contaminated by human or animal faeces or urine containing pathogenic bacteria or viruses; include cholera, typhoid, amoebic and bacillary dysentery and other diarrhoeal diseases. Primarily talking about diarrhoea
Each year people in the world have some 4,000,000,000 to 8,000,000,000 episodes of diarrhoea. That s equal in volume to about 15 minutes flow over the Niagara Falls!!
1.8 million people die every year from diarrhoeal diseases (including cholera); 90% are children under 5, mostly in developing countries. 88% of diarrhoeal disease is attributed to unsafe water supply, inadequate sanitation and hygiene.
In 2002, 1.1 billion people lacked access to improved water sources, which represented 17% of the global population. In 2002, 2.6 billion people lacked access to improved sanitation, which represented 42% of the world s population.
We estimated the disease burden from water, sanitation, and hygiene to be 4.0% of all deaths and 5.7% of the total disease burden (in DALYs) occurring worldwide, taking into account diarrheal diseases, schistosomiasis, trachoma, ascariasis, trichuriasis, and hookworm disease. Annette Prüss, David Kay, Lorna Fewtrell, and Jamie Bartram (EHP 2002)
Scenario Description Min RR Realistic RR I Ideal situation, corresponding to the absence of transmission of diarrhoeal disease through WSH 1 1 II III Population having access to piped water in-house where more than 98% of the population is served by those services; generally corresponds to regulated water supply and full sanitation coverage, with partial treatment of sewage and is typical in developed countries. Piped water in-house and improved sanitation services in countries where less than 98% of the population is served by water supply and sanitation services, and where water supply is likely not to be routinely controlled. 2.5 2.5 2.5 4.5
Scenario Description Min RR Realistic RR IV Vb VI Population having access to improved water supply and improved sanitation in countries where less than 98% of the population is served by water supply and sanitation services and where water supply is likely not to be routinely controlled. Population having access to improved water supply but not served with improved sanitation in countries which are not extensively covered by those services Population not served with improved water supply and no improved sanitation in countries which are not extensively cover by those services (less than 98% coverage), and where water supply is not likely to be routinely controlled 3.8 6.9 4.8 8.7 6.1 11.0
Or is it?
Empowering local communities to better look after their own drinking water systems Identification of community leaders Provision of training Help in supervision Monitoring impact on self-reported diarrhoea At time of intervention Some 15 months later (and comparison with control systems)
In non intervention water systems which are governed by US regulations At least 50% of all cases of diarrhoea due to inadequately treated drinking water Approximately 10% of diarrhoea associated with problems with sewage disposal
High levels are waterborne disease are not necessarily limited to developing countries We do not have to wait until we can afford a system that will deliver water to best quality and safety standards Some water interventions can have social and economic benefits than just disease reduction
Distribution problems and health risk
Intermediary Events in European waterborne outbreaks Event Frequency (N=61) Mean score for positive events Source Water 41 (67%) 50.46 Treatment 41 (67%) 49.00 Distribution 19 (31%) 87.42 Monitoring 16 (26%) 22.56
Distribution Base Freq. (%) (n=19) Events Base Event Mean score (+ve events) Consruct./Repair 4 (6.56) 47.75 Flushing/Cleaning 2 (3.28) 22.5 Ext.Back./X-conn. 9 (14.75) 85.44 Worries about old and failing distribution networks Int.Back./X-conn. Low Pressure Stagnant Water Damaged/Old Main Rsrvr/Str.TnkCont. Regrowth Intermed. Tmt Other Distribution 1 (1.64) 2 (3.28) 1 (1.64) 3 (4.92) 1 (1.64) 1 (1.64) 2 (3.28) 1 (1.64) 95 12.5 45 49.33 100 3 70 100 (-)
Final model in case-control study of self reported diarrhoea Adjusted OR 95% CI P Feeding child under 5 Y N 2.520 1.000 1.045 6.079 0.040 Contact with another case Y N 6.959 1.000 2.296 21.092 0.001 Loss of water pressure at home Y N 12.496 1.000 3.493 44.707 <0.001 How often eat yoghurt / wk 0 1 2 1.000 0.947 0.319 2.815 0.016 3 7 0.283 0.083 0.970 >7 0.186 0.054 0.641 Hunter et al. 2005 Clinical Infectious Diseases
Distribution problems in developing countries
Factors impacting on risk Social class Vulnerability Incompetent management Other transmission pathways Extreme weather events
Caused by poor personal hygiene and skin or eye contact with contaminated water; include scabies, trachoma and flea, lice and tick-borne diseases.
Caused by parasites found in intermediate organisms living in water; include dracunculiasis, schistosomiasis and other helminths.
Caused by insect vectors which breed in water; include dengue, filariasis, malaria, onchocerciasis, trypanosomiasisand yellow fever.
291 cases among 96 860 refugees over 13 months (AR 0.30%) 43 died Outbreak started at reception centre at Pachara after a big influx of refugees and then spread to the rest of the camp Eventually controlled by massive immunisation campaign
Spread of disease followed routes where people had to walk to get water. First study of the protective effect of meningococcal immunisation in refugee populations 83.8%
Parasitic intestinal diseases Chemical contamination e.g. Arsenic Fluoride Micro-nutrients Magnesium Musculoskeletal problems And the rest? Cancers? Birth defects etc
Environmental justice
Estimated diseases burden/ 1000 s DALYS Developing regions Rheumatoid arthritis 3,238 1,520 Osteoarthritis 11,049 5,323 Other musculoskeletal diseases All musculoskeletal diseases 6,789 1,880 21,076 8,723 Developed regions
Very little good data on prevalence of lower back pain in developing countries Very little good data on risk factors for lower back pain in developing countries, especially in children No data on relationship between water carriage and lower back pain
Backpack and back ache Some evidence of an association from US between backpack weight and self-reported back pain in children (Skaggs et al. 2006; Mooreet al. 2007) However evidence is conflicting We really do not have much of an idea how much water carrying contributes to back pain in adults or in children We also do not know the long term impacts of carrying water as a child on subsequent development
An economic analysis of improvements in water and sanitation
Early themes Benefits of water quality/supply improvements more than just impact on diarrhoeal disease Other diseases Wider social benefits Waiting to be able to deliver a system that complies fully with WHO standards is not appropriate. The most cost effective intervention is the first one One of the biggest impacts on cost of intervention is sustainability
An intervention that is not used or which fails prematurely is very costly and has little benefit.
Conclusions
Conclusions Drinking water is essential for health Chemically and microbiologically contaminated drinking water causes both acute and chronic ill health. Adverse health effects of inadequate water and sanitation include more than just diarrhoeal disease
Conclusions Rapid provision of drinking water supplies fully complying with WHO guidelines is unlikely to happen. But this is not an excuse for doing nothing, considerable public health gains are achievable from much more modest interventions