Classification of Water-related diseases
Water may carry causative agents (pathogens) of communicable diseases of man or provide the right environment for the breeding and propagation of their vectors. Irrigation and drainage projects create great expanses of water and, provided a number of ecological conditions are mer, will lead to the introduction of disease vectors in areas where they did not occur before, or to a rapid increase of their original densities. Wherever a parasite or another disease causing organism is present, and a susceptible human population exists, environmental changes resulting from such projects may have a profound impact on the epidemiology of disease through their effect on vector bionomics. In addition, sometimes the disease agent is introduced by human migration resulting directly from project development. Disease transmission may be particularly rapid in densely populated areas associated with irrigated lands. The adverse effects of irrigation may be related to oversights at the initial planning and construction of the system, or to its mismanagement in the operational phase. Water-related diseases may be avoided or mitigated by good engineering practice and by appropriate water management.
Water-related diseases can be classified into 4 major categories, as follows:
- Water-borne diseases: infections spread through contaminated drinking water (Diarrhoeal Diseases, Typhoid Fever)
- Water-washed diseases: diseases due to the lack of proper sanitation and hygiene (Ascariasis =roundworm infection, Ancylostomiasis (=hookworm infection)
- Water-based diseases: infections transmitted through an aquatic invertebrate organism (Schistosomiasis, (Bilharzia),
- Water-related vector-borne diseases diseases transmitted by insects that depend on water for their propagation (Malaria, Lymphatic filariasis, Onchocerciasis , Japanese encephalitis)