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Category: Environmental Microbiology
Detection of Protozoan Parasites in Source and Finished Drinking Water, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815882/9781555813796_Chap21-1.gif /docserver/preview/fulltext/10.1128/9781555815882/9781555813796_Chap21-2.gifAbstract:
This chapter deals primarily with human enteric protozoa and more specifically Giardia and Cryptosporidium. Presently, Giardia and Cryptosporidium are of great concern to the water treatment industry, because they are known to be the etiologic agents responsible for a number of episodes of waterborne gastroenteritis. In many cases the only way to accurately identify some free-living protozoans to genus and species is to collaborate with experts in the field. Giardia lamblia is one of the most frequently reported parasitic water-borne pathogens. Detection of G. lamblia and C. parvum in source and finished water has been and continues to be of great interest. It is an immunofluorescence detection procedure performed after concentration of protozoans from large volumes of water. A section assumes use of a microscope, capable of epifluorescence and differential interference contrast (DIC) microscopy or Hoffman modulation optics, with stage and ocular micrometers and 20× (numerical aperture = 0.6) to 100× (numerical aperture = 1.3) oil immersion objectives. Microscopic examination also assumes that the ocular micrometer has been calibrated. The fluorescence in situ hybridization (FISH) assay can also be evaluated with a standard epifluorescence microscope. The major advance in using this approach is that the occurrence of false positives is reduced and that the need for DIC optics is eliminated. Depending upon the source or expert consulted, B. hominis either may or may not be classified as a pathogen.
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Giardia cysts and Cryptosporidium oocysts were stained by immuno-FA and DAPI and were also viewed by Nomarski DIC microscopy. (A) Immuno-FA-stained G. lamblia cyst. (B) DAPI-stained G. lamblia cysts. Nu, nucleus. (C) Nomarski DIC photomicrograph of G. lamblia cysts. Mb, median body; Ax, axonemes. (D) Immuno-FA-stained C. parvum oocysts. (E) DAPI-stained C. parvum oocysts. (F) Nomarski DIC photomicrograph of C. parvum oocyst. S, sporozoite (three showing). Bars = 5 μm. (Photomicrographs courtesy of Michael W. Ware, U.S. Environmental Protection Agency.)
Water sampling apparatus.
Methods for scanning a well slide.
QC acceptance criteria for Cryptosporidium
QC acceptance criteria for Giardia