Water for people.pdf - WHO Thailand Digital Repository

1 1 4 / C H A L L E N G E S T O L I F E A N D W E L L - B E I N GBasic Needs and the Right to HealthThe relative importance of water in adequate quantities, as comparedto water quality, sanitation and hygiene, has been the subject ofdebate for many years, yet so far, no international norms forminimum domestic water quantities have been formally proposed.International targets, including the Millennium Development Goals,tend to omit this aspect. Domestic water is defined as water used forall usual household purposes including consumption, bathing andcooking, yet it must be borne in mind when interpreting andapplying minimum values for water quantity, that some of these usesoccur at home, while others (for example, laundry and bathing)occur away from the home. Some household-level use may also gobeyond the conventional concept of what is domestic, and enter inthe productive sphere: horticulture, livestock watering, constructionand wholesale preparation of food and beverages. These homeproducts may be essential for the livelihood of poor households.It has been suggested that poor hygiene may, in part, be tracedback to lack of water in sufficient quantity (Cairncross and Feachem,1993), but reviews of numerous studies on various different singleand multiple water and sanitation interventions have beeninconclusive on the relative contribution of water quantity, and havesometimes detected contradictory results. Early studies seem tosuggest that increased water quantity has an edge over waterquality in its effectiveness to reduce diarrhoeal disease incidence, butlater studies contradict this and in fact seem to indicate that neitherquality nor quantity improvements result in significant health gainswithout concomitant sanitation improvement. From the variability andinconsistencies observed, the most tenable conclusion is that allinterventions potentially have a significant impact and that the scaleand relative impact of a single intervention depends strongly on theexposure route that is predominant under local conditions at aspecific point in time. The complex exposure routes of most faecaloralinfections (see figure 5.1) make it hard to predict whichintervention, whether single or a combination of measures, will bemost effective. For some infections, however, the exposure pathwayis simple. This is the case of the Guinea worm infection (see box 5.3)for which the exposure pathway is singular (although biologicallycomplex) and has permitted the success of the Guinea wormeradication programme. In this case, however, interruptingtransmission is not a matter of quantity but of quality.There is evidence that the public health gains derived from useof increased volumes of water typically occur in two majorincrements. The first increment occurs when the total lack of basicaccess is overcome, leading to the availability of volumes adequateto support basic personal hygiene. A further significant health gainoccurs when water supply becomes available at the household level(Howard and Bartram, in prep.). Some studies indicate that thehealth gains of increased water quantities are greater for some agegroups than for others. Studies from India suggest that waterquality is more critical for the health of children under three, whilewater quantity becomes a crucial health determinant above the age ofBox 5.3: The role of improved water supply in the eradication of Guinea worm infectionGuinea worm (Dracunculus medinensis) is a parasiticworm that causes an infection called dracunculiasis orGuinea worm disease. The disease eradication efforts ofthe past decade or so dramatically demonstrate the powerof water supply interventions.Water is fundamental in the dracunculiasis transmissioncycle. People get the infection from drinking water withinfected intermediate hosts of the genus Cyclops. Thelarvae develop into long parasitic worms that lodge in thejoints, particularly the knees, where they cause a blister.From the blister, eggs are released, develop into larvae andcomplete the cycle in the Cyclops intermediate host.Dracunculiasis is a disabling disease with a seasonalpattern, often peaking at times in the agricultural yearwhen labour is in maximum demand. For this reasondracunculiasis is also known as the ‘empty granary’ disease.The unique ecology of the Drancunculus parasitemake the provision of an improved water supply asingular, critical intervention to interrupt transmission. Theevidence for the impact of improved water supplies ondracunculiasis is clear in, for example, India, where it wasresponsible for a 80 to 98 percent reduction in annualincidence (adapted from Cairncross et al., 2002).The Guinea worm eradication campaign started in 1989and it is lead primarily by WHO, UNICEF and the CarterCenter. Before the beginning of the campaign more thanthree million cases were estimated worldwide (Watts,1987). Since then, WHO has certified 151 countries asGuinea worm disease-free and five more are in precertificationphase. Among the certified countries, Indiaand Pakistan achieved interruption of transmission after thebeginning of the global eradication campaign in the 1980s.Nowadays only thirteen nations still have the disease andreported a total of 60,000 cases in 2001 (WHO, 2002a).Sources: Cairncross et al., 2002; Watts, 1987; WHO, 2002a.