Water as a vector for infectious stages of parasites in lifestock.

Water is a key factor in the life cycle of many parasite species. The devel opment of the free-living generation (oocysts, cysts, eggs, larvae) and the longevity of the resulting infectious stages are extremely dependent on th e availability of water. Damp stables are principally associated with an in creased risk of parasite infection. Infectious stages may accumulate in dir ty watering equipment and in pools of water on pasture. Utilization of surf ace water, especially when contaminated with sewage or effluent from sewage plants, imposes an increased risk of parasite infection on farm animals. F looding of pastures with water containing parasite stages can lead to exten sive contamination. Rainfall, flooding or inadequate land disposal of manur e may contaminate surface water with parasite stages of animal origin from adjacent agricultural areas.