Water borne diseases

Water borne diseases are endemic to many parts of the world. Many common ailments are transmitted via water by unhygienic or unsanitary practices. It is well known that simple cleanliness, particularly having clean hands whenever they come in contact with stored or

transported water is very important. Myriad bacteria are transferred from dirty hands to water to mouth and gut to develop into one or another form of enteric infection. These infections can be manifest in the form of a slight reduction in an individuals normal comfort level, to the other extreme of serious illnesses such as cholera, typhoid, hepatitis, dysentery or one of many other potentially deadly diseases. These problems become more serious as water becomes more scarce because there is then thought to be less water available for washing. The opposite is true. As the resource becomes more precious the need for cleanliness, and in particular for hand washing before any contact with water becomes imperative. Where water is very scarce this precautionary behaviour is rarely practiced and as a result stomach upsets, and worse, are part of the daily expectations, which significantly lower enjoyment of life and eventually shorten it. Prevention of these problems is quite possible but it needs education and discipline.

Education concerning water consumption and hygiene needs to begin with the very young at home, and should be reinforced by continual reminders in all school curricula, beginning in the first days of school attendance.

Any form of water resource development causes changes in natural conditions. Many of these changes offer opportunities for multiplication of numerous disease vectors, which may have produced little or no problems under natural conditions, but with the changes could have devastating effects. An example would be development of a tube-well to raise water to the surface. When the water is temporarily held in a surface tank or reservoir it provides opportunity for breeding of mosquitoes and flies. These opportunities were not available when the water was stored only in the aquifer. In regions where malaria, dengue fever or similar insect transmitted diseases are endemic, storage of water on the surface needs to be accompanied by precautionary measures to prevent the surface water becoming a breeding site for these disease transmitters.

In the tropics, almost all water resources development tends to increase the opportunities for some type of undesirable, and in many cases deadly, disease vector. This means that an integral part of any tropical water resource development plan, particularly in areas of water scarcity, needs to be an overt, up-front plan to prevent any increase in these preventable diseases. This means that planners must investigate what diseases could possibly increase with the development and then implement measures for their prevention.

In most cases this will mean changing the method of implementation of the scheme and probably raise the cost of the project. But with innovative ideas the changes and extra costs need not be large. Failure to do this results in people’s lives being changed for the better by increased availability of water, but for the worse by increased morbidity. In some earlier developments the increase in disease and shortening of life expectancy has been (and continues to be) so large that even now it would probably be better if the developments were abandoned. Examples are to be found in power production reservoirs, and in many irrigation developments in regions where river blindness and schistosomiasis are endemic.

The more common preventable insect transmitted diseases resulting from water resources development, mainly in the tropics, are malaria, dengue, encephalitis, river blindness, and schistosomiasis. All of these can be kept in check by a combination of biological/entomological understanding and engineering works and management. It is beyond the scope of this book to discuss preventive measures, but these are available in many other references. However it is important that planners, decision makers and

financiers include disease prevention as an integral part of any water resource development project.

5.6. Conclusion

In regions where water is scare the small local population has usually been effective in deriving the water it needs for an acceptable lifestyle. However as populations increase there is often a need to

ƒ Make better (optimal) use of the usual water sources.

ƒ Find more water.

ƒ Carefully protect all the water.

Protection is needed to prevent, or at least minimise evaporation and seepage of stored water and to prevent physical, chemical and biological contamination. The principles of how to collect more water, how to make better use of what is collected and how to protect it from spoilation have been discussed in this chapter and some examples have been given of practical ways of conserving water supplies. Some of the principles involve cultural practices and beliefs, and hence change to these, requiring sensitivity and understanding, will only occur slowly. The majority of issues where change could be worthwhile involve only simple common sense and logic, and it should be possible, with some determination and will to quickly implement these anywhere.