Quantification of helminth eggs in waste water.

Agricultural use of waste water has been regulated mostly by its bacteriological quality. Recently the importance of parasitological criteria for waste water standards was recognized by establishing that waste water containing less than 1 intestinal Nematode egg per liter is released for unrestricted use of effluents. At present, most of the techniques borrowed from parasitological coprology are only qualitative. In this report different protocols for helminth egg quantitation were compared. Three flotation techniques (Janeckso-Urbanyi, Faust, Arther) and two sedimentation techniques (Bailenger, Ritchie) and their performances were evaluated. Although all the techniques were based on the same number of on the whole positive samples, significant differences were observed in both the number of species identified and in the type of egg preferentially concentrated. Among the flotation methods tested, the Janeckso-Urbanyi modality offers undeniable advantages in efficiency and in the variety of species concentrated, but it is relatively costly. Among the sedimentation techniques, the one described by Bailenger is relatively inexpensive and concentrates all the types of eggs normally found in waste water samples, except for the relatively rare Enterobius with globally satisfactory yields.