Giardia Cysts Cryptosporidium Oocysts and Ascaris Eggs in Bean Sprouts and Other Vegetables

Isolationand Enumeration of Giardia Cysts, Cryptosporidium Oocysts, and Ascaris Eggs fromFruits and Vegetables

June 2000
Journal of Food Protection
Vol. 63, No. 6, pp. 775­778.
L. J. Robertson And B. Gjerde

Published techniques for recovering parasites from fruit and vegetables aregenerally inadequate, with low and variable recovery efficiencies. Here wedescribe an improved methodology for analyzing fruit and vegetables for Giardiacysts, Cryptosporidium oocysts, and Ascaris eggs. The method includes washingprocedures, sonication, and, for Giardia and Cryptosporidium, immunomagneticseparation.

Identificationis by immunofluorescence (Giardia and Cryptosporidium) or brightfield microscopy(Ascaris). Recovery efficiencies from lettuce, Chinese leaves, and strawberrieswere found to be approximately 67% for Giardia, 42% for Cryptosporidium, and 72%for Ascaris.

Recoveryefficiencies from bean sprouts tended to be more variable and lower. Thiscould be due to material removed with the parasites during the washingprocedures, which, in turn, appeared related to the age of the bean sprouts. Itis therefore recommended that fruit and vegetables should be as fresh aspossible when analyzed for parasites.