What are the greatest drinking-water and sanitation dangers to human health, and who are the most vulnerable groups?
Infectious disease transmission is the greatest risk after an emergency. The diseases and conditions of ill-health directly associated with water, sanitation and hygiene include infectious diarrhoea (which, in turn, includes cholera, salmonellosis, shigellosis, amoebiasis and a number of other protozoal and viral infections), typhoid and paratyphoid fevers, acute hepatitis A, acute hepatitis E and F, schistosomiasis, trachoma, intestinal helminth infections (including ascariasis, trichuriasis and hookworm infection), dracunculiasis, scabies, dengue, leptopirosis, the filariases (including lymphatic filariasis and onchocerciasis), malaria, Japanese encephalitis, West Nile virus infection, yellow fever and impetigo. Not all these diseases are relevant to all the affected countries. The spread of most of these diseases is of special concern where sanitation systems are disrupted and where excreta has been distributed widely by flooding. The most vulnerable groups are children under five and the elderly. About 90 per cent of the deaths due to diarrhoea occur in children under 5.
Although infectious diseases will pose the greatest health risks, in some cases toxic chemicals may enter water supplies, especially when there has been massive flooding.
Drinking water sources away from sources of chemical or microbial contamination should be used as supplies. If this is not possible, alternative supplies of water may be required (e.g., bottled water or supplies through tanker trucks).