Factors affecting recovery efficiency in isolation of Cryptosporidium oocysts and Giardia cysts from vegetables for standard method development

While recently published techniques for recovering parasites from fruits an d vegetables demonstrate a marked increase in efficiency and utility, there is still scope for further improvement in developing a standard method, pa rticularly with difficult, but important, sample matrices such as bean spro uts. Herein, a number of parameters used in published techniques are invest igated more closely. While sample size reduction may improve recovery effic iency because of a range of factors, it is important to keep the sample lar ge enough for detection of low-level contamination. Age of sample is also i mportant, and samples should be as fresh as possible. Elution procedures ma y contribute to losses of Giardia and should be more thoroughly investigate d. Improved immunomagnetic separation techniques currently coming onto the market also have the potential to increase recovery efficiency substantiall y, even with difficult samples such as aged bean sprouts. However merely in creasing magnetic strength of the capturing magnet does not affect recovery efficiency, which must be reliant on a superior bead system, buffering sys tem, or both.