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DETECTION OF GIARDIA MURIS AND GIARDIA LAMBLIA CYSTS BY IMMUNOFLUORESCENCE IN ANIMAL TISSUES AND FECAL SAMPLES SUBJECTED TO CYCLES OF FREEZING AND THAWING
Citation:
Erlandsen, S., L. Sherlock, AND W. Bemrick. DETECTION OF GIARDIA MURIS AND GIARDIA LAMBLIA CYSTS BY IMMUNOFLUORESCENCE IN ANIMAL TISSUES AND FECAL SAMPLES SUBJECTED TO CYCLES OF FREEZING AND THAWING. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-90/095 (NTIS PB91171777).
Description:
The effects of freezing and thawing on the detection of selected Giardia spp. cysts were investigated using immunofluorescence, bright field microscopy, and low voltage scanning electron microscopy (SEM). iardia muris cysts were obtained from either animal carcasses, fecal pellets, or isolated cyst preparations; while Giardia lamblia cysts were isolated from fecal samples. hese samples were stained using an immunofluorescence technique after 1 to 3 freezing (-16 C) and thawing (20 C) cycles. ysts were detected successfully by immunofluorescence in all samples. owever, in those samples subjected to freeze-thawing, the cyst walls often became distorted and then were not detectable by bright field microscopy. ow voltage SEM demonstrated that the filaments in the distorted cyst wall underwent rearrangements of interfilament spacing. uantitation of cyst recovery after freezing and thawing demonstrated that a substantial loss occurred after 1 cycle of alternating temperature when low concentrations of cysts were used, but not with high concentrations of cysts. yst recovery, after 3 freezing and thawing cycles, was dramatically lowered irrespective of the initial cyst concentration. hese results demonstrated that immunofluorescence was an effective technique for the detection of Giardia spp. cysts in frozen samples and would suggest that freezing and thawing of fecal samples could prevent the detection of cysts when only bright field microscopy was employed.