Giardia and Cryptosporidium generally occur in very low numbers in aquatic environments (West 1991). Therefore, testing potential drinking water sources requires filtering large volumes of water through small-pore filter cartridges (1µ nominal). The cysts are then extracted from the filters for examination. Methods are complex, inefficient, and imprecise (Isaac-Renton 1995, Reofer et al. 1996). Recovery efficiencies averaged 2.9 percent (range 0.8—22.3 percent) in studies of commercial laboratories (Reofer et al. 1996). The maximum recovery expected with this method is 25 percent (Wallis 1997). No standard methods for Giardia / Cryptosporidium sampling are currently available. This report details a practical field method for Giardia / Cryptosporidium determination in freshwater based on methods used by other agencies (Isaac-Renton 1995) for field surveys.
Lucas, Barbara G. 1997. Field Methods for Giardia and Cryptosporidium Sample Collection. BC Ministry of Environment Lands and Parks
Keywords: giardia, cryptosporidium, drinking water
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