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

The performances of different concentration and elution tecniques, as well as two purification methods, were evaluated in terms of their recovery efficiencies of Giardia cysts and Cryptosporidium oocysts from seeded deionized water, treated water, and raw water samples. Out of the three concentration techniques, the Envirochek capsule filtration followed by the membrane filtration consistently gave the highest recovery efficiencies for both protozoan parasites. Although the cartridge filtration is the most suitable technique for handling large quantities of water, it also brought the greatest loss of protozoan parasites. For elution and centrifugation, both the membrane filter with hand-kneading and Envirochek capsule with wristaction shaking attained higher recovery efficiencies for cysts and oocysts. Immunomagnetic separation (IMS), the purification procedure in Method 1623, had a much higher recovery efficiency for both Giardia and Cryptosporidium than the Percoll-sucrose density gradient purification, which was the flotation procedure of the Information Collection Requirements Rule (ICR) protozoan method. 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 density gradient purification. In general, Giardia cysts attained a higher recovery efficiency. The recovery efficiencies of Method 1623, due to the use of Envirochek capsule filtration combined with the IMS, were 48.0% and 37.2% higher for Giardia and Cryptosporidium, respectively, than the ICR protozoan method for the three types of water.