Parasites and the land application of sewage sludge

Parasite ova, mainly Ascaris and Toxocara, were recovered from many Ontario sewage sludges, and from sludged fields. These ova can survive on pasture for several years, are probably destroyed on bare soil within one year and possibly survive only a few weeks when the sludge is mixed with the soil. This information, together with the type of parasites present in Ontario and the numbers found in the digested sludge, make noticeable parasite transmission, via sludge spread on farmland, a remote possibility. Recommendations are made for the use and handling of sludge that will reduce the possibility of transmission even further.