Esteban et al. (2002) describe the serious human fascioliasis problem in a high-altitude area of Peru which they claim is associated with man-made irrigation systems colonized by lymnaeid snails. Therefore, as one of the outcomes of their study, they question the rationality of the ongoing construction of new irrigation schemes. This recommendation is surprising in view of the statement in the same paper that ‘inhabitants obtain water from irrigation canals and drainage channels for all their needs (drinking, cooking, personal hygiene, cleaning and washing)’ and that 97.9% of the inhabitants obtain their drinking water from the irrigation resources.
This suggests that the irrigation system provides important health benefits by making water available for domestic use. If the amounts of water are in excess of what the inhabitants would have available without the irrigation canals, a reduction of hygiene-related diarrhoeal, skin and eye diseases could be expected. We have documented the importance of irrigation canal water for human health in Pakistan (Van der Hoek et al. 2001). In addition to the potential health benefits, irrigation could generate better livelihoods by improving socio-economic and nutritional standards. Irrigation should not be banned because of the risks associated with fascioliasis. Instead, a health impact assessment should be compulsory for all new irrigation projects (Birley & Lock 1999), which should take all potential negative as well as positive health consequences into consideration and make sure that mitigating measures are incorporated into any new project or rehabilitation process. This means that after identifying the risks, a fascioliasis control effort should be implemented and the capacity of protective agencies improved as part of any project in the area. Also, special ecological risks associated with the cultivation practices or infrastructure should be addressed. Only then, with this more balanced approach, can the health sector be a serious partner in intersectoral decision-making and contribute to the overall cost-benefit analysis of development projects.
Wim van der Hoek , Flemming Konradsen and Feliz Amerasinghe
International Water Management Institute, Colombo, Sri Lanka
Department of International Health, University of Copenhagen, Copenhagen, Denmark