[Water as a vector for infectious stages of parasites in livestock]

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