Water for people.pdf - WHO Thailand Digital Repository

1 0 8 / 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 HealthThere is no vaccine against schistosomes, which infect mainlychildren and adolescents, as well as those in frequent and closetouch with contaminated water for occupational reasons, such asirrigation farmers. There is, however, an effective drug, Praziquantl,whose price has come down considerably in recent years.Nevertheless use of the drug has not succeeded in breakingthrough the cycle of water contamination and reinfection. Theremaining prevalence of infection following various rounds of massdrug treatment reflects the state of sanitation facilities, hygienebehaviour and environmental receptivity. Without addressing thesedeterminants through improved irrigation water management, forexample, the economic feasibility of maintaining results of massdrug treatment campaigns is low.Lymphatic filariasisLymphatic filariasis is a mosquito-borne parasitic worm infection,which in its most dramatic form is expressed in the symptoms ofelephantiasis, the accumulation of lymph, usually in the legs. It isnot a killer disease, but causes severe debilitation and social stigma.So while the number of deaths from filariasis is close to zero, theburden of disease value is relatively high, globally estimated at5.6 million DALYs in 2001. Urban populations in Africa and southand South-East Asia are most affected, although some rural cottageindustries also provide conditions that favour the Culex vectors: inSri Lanka, coconut husk pits, where coconut shells are left to rot toharvest the fibre, are notorious breeding places and communitiesengaging in this practice tend to have high infection rates.International efforts are underway to eliminate filariasis as aglobal public health problem. These have become possible thanks togreatly improved diagnostic techniques and dramatic advances intreatment methods – both for controlling the spread of thisinfection and for alleviating its symptoms. Partnerships with thepharmaceutical industry ensure that drugs are available whereverthey are needed.Improvements in urban water management will provide a solidbasis for the progress that is being made through these health sectorefforts. The improvements should focus on the infrastructure forsewage and stormwater drainage and for collection of wastewaterbefore its treatment and possible reuse. Two parasite species causelymphatic filariasis and the one of lesser public health importance(Brughia malayi) is transmitted by mosquitoes of the genus Mansoniawhose breeding is associated with aquatic weeds. Proper managementof reservoirs, i.e. the harvesting or elimination of aquatic weeds, meetsdual objectives: reduced evapotranspiration from the reservoir and aneffective interruption of transmission of this parasite.Arboviral infectionsArboviral infections are acute and have high mortality rates; infectionoutbreaks occur in a cyclical way, and as a result, burden of diseaseestimates vary greatly from one year to another. In 2001, theestimate of the burden of two arboviral diseases (dengue andJapanese encephalitis) combined amounted to about 1.4 millionDALYs.The association with water is disease-specific. The distribution ofJapanese encephalitis is from east to south Asia, with a strong link toflooded rice ecosystems, where the main vectors of the Culextritaeniorrhynchus/gelidus group breed. The Aedes vectors ofdengue breed in small, domestic collections of water (flower vases,dumped car tyres and standing water in solid waste dumps). Thewater management practices to prevent arbovirus transmission andoutbreaks of arboviral diseases are similarly disease- and sitespecific.In some countries, for example India, the provision ofdrinking water supplies in rural areas has contributed to increaseddengue risks. In instances where there is an unreliable supply, peopletend to collect water when it is available and store it in their house.Such domestic water storage may become a prime source of Aedesmosquitoes.Water Management for HealthDrinking water supply and sanitationWater supply, sanitation and hygiene improvements have a longhistory as public health interventions, and the rationale for theirpromotion has mainly relied on the substantial reductions inmorbidity and mortality they can achieve, especially in thedeveloping world. Yet the Global Water Supply and Sanitation 2000Assessment (WHO/UNICEF, 2000) shows that 1.1 billion people lackaccess to improved water supply and 2.4 billion to improvedsanitation. In the vicious poverty-ill-health cycle, inadequate watersupply and sanitation are both the underlying cause and theoutcome: invariably, those who lack adequate and affordable watersupplies are the poorest in society. If improved water supply andbasic sanitation were extended to the present-day ‘unserved’, it isestimated that the burden of infectious diarrhoeas would bereduced by some 17 percent; if universal piped, well-regulatedwater supply and full sanitation were achieved, this would reducethe burden by some 70 percent. Improvements such as these wouldalso lead to reductions in other water-, sanitation- and hygienerelateddiseases, such as schistosomiasis, trachoma and infectioushepatitis.The 2000 Assessment established that most of the unservedpopulations are in Asia and Africa. In absolute terms, Asia has thehighest number of underserved, but proportionally this group is bigger