[Occurrence of Giardia and Cryptosporidium in wastewater, surface water and ground water samples in Palermo (Sicily)].

This paper reports the investigation carried out on the occurrence of Cryptosporidium and Giardia (oo)cysts in water samples of two municipal treatment plants, and in surface water and ground water wells of the province of Palermo. The wastewater samples taken before and after treatment process were assayed over the course of one year Giardia cysts were detected in all samples throught the year at higher concentration levels than Cryptosporidium oocysts, with a peak observed in spring. The overall removal efficiency of (oo)cysts in the treatment plants was about of 90%. Their presence were also searched in surface waters (three artificial lakes and one river); (oo)cysts were detected in one lake at very low concentration; on the contrary, both parasites were found at high concentration levels in all the samples collected throught one year from the water of the river. The pattern of occurrence of both parasites appears temporally related to the level of rainfall trend. Cryptosporidium and Giardia were also found in ground water wells; their presence occurred only in waters taken from wells at a depth lower than 31 meters with concomitant presence of faecal bacteria. These results may provide further insight into the possible source of Cryptosporidium and Giardia in natural environmental and stress the potential risk associated with the use of waters for recreational and agricultural purposes.