Fate of pathogenic parasites in sewage sediments and environmental components

The purpose of the current study was the assessment of the persistence of Ascaris eggs and Giardia cysts in sewage products and environmental components commonly implicated in the transmission of these pathogen parasites. In fact, wastewater and sewage sediments reuse for agricultural purposes has the potential to contaminate water supplies, soil and crops. The ability of parasites cysts to persist in the environment may threaten public health. So, destruction rates of parasite cysts and eggs in stored sediments, crops and soil were examined to help understand the fate of these agents in sewage products and environmental components. In lagoon stored sewage sediments, Ascaris eggs disappeared after approximately 180 days of storage versus 49 days for sediments stored under ambient laboratory conditions, and less than 18 days in dried sediments. Giardia cysts persisted less than one month lagoon-stored sediments, up to 24 days under laboratory conditions and less than 9 days in dried sediments. For parasites persistence on crops, Ascaris eggs persisted on lucerne for 6 days while Giardia cysts have not been detected for longer periods than 3 days after contamination. In soil, Ascaris eggs were not isolated in periods greater than 90 days, while Giardia cysts were not discovered 3 days after contamination induced by wastewater.