The detection of protozoa such asCryptosporidiumoocysts is carried out by the process of concentrating a large amount of water samples (10L or more), and separating and purifying the oocysts/ cysts (density gradient centrifugation method), to detect the protozoa. The concentration of the water samples is a time-consuming process, which at the same time defines the detection sensitivity (recovery rate) . In general, the concentration process is carried out by filtration with a filter, or by centrifugal precipitation method. However, there are some drawbacks in each of these means such that there is a limitation in the retaining ability of the residue in the filtration with a filter, and that the centrifugal precipitation method is not suitable for a large volume sample.
The present study has remarked on a small continuous flow concentrator, and in order to achieve improvement in the concentration accuracy and speeding up the concentration process, improvements on the miniaturization of a small continuous flow centrifugation rotor (internal volume 80ml) . The samples concentrated by this continuous flow rotor could be immediately applied to a subsequent sucrose flotation method, whereby contributing the reduction of required time period and improvements in the recovery rate by the simplification in the concentration process. The recovery rate in the recovery test using the actualCryptosporidiumoocysts was also sufficient, so that the present method could be an effective choice for the concentration of samples.

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