Recovery of Giardia and Cryptosporidium from water by various concentration, elution, and purification techniques

The performances of different concentration and elution techniques, as well as two purification methods, were evaluated in terms of their recovery eff iciencies of Giardia cysts and Cryptosporidium oocysts from seeded deionize d water, treated water, and raw water samples. Out of the three concentrati on techniques, the Envirochek capsule filtration followed by the membrane f iltration consistently gave the highest recovery efficiencies for both prot ozoan parasites. Although the cartridge filtration is the most suitable tec hnique for handling large quantities of water, it also brought the greatest loss of protozoan parasites. For elution and centrifugation, both the memb rane filter with hand-kneading and Envirochek capsule with wrist-action sha king attained higher recovery efficiencies for cysts and oocysts. Immunomag netic separation (IMS), the purification procedure in Method 1623, had a mu ch higher recovery efficiency for both Giardia and Cryptosporidium than the Percoll-sucrose density gradient purification, which was the notation proc edure of the Information Collection Requirements Rule (ICR) protozoan metho d. Recovery efficiencies of IMS were 78.6% (SD = 13.7%) and 69.3% (SD = 13. 3%) for cysts and oocysts, respectively, in contrast to the 22.7% (SD = 14. 5%) for cysts and 29.9% (SD = 20.3%) for oocysts by using Percoll-sucrose d ensity gradient purification. In general, Giardia cysts attained a higher r ecovery efficiency. The recovery efficiencies of Method 1623, due to the us e of Envirochek capsule filtration combined with the IMS, were 48.0% and 37 .2% higher for Giardia and Cryptosporidium, respectively, than the ICR prot ozoan method for the three types of water.