Abstract
The steps of two immunofluorescent-antibody-based detection methods were evaluated for their efficiencies in detecting Giardia cysts and Cryptosporidium oocysts. The two methods evaluated were the American Society for Testing and Materials proposed test method for Giardia cysts and Cryptosporidium oocysts in low-turbidity water and a procedure employing sampling by membrane filtration, Percoll-Percoll step gradient, and immunofluorescent staining. The membrane filter sampling method was characterized by higher recovery rates in all three types of waters tested: raw surface water, partially treated water from a flocculation basin, and filtered water. Cyst and oocyst recovery efficiencies decreased with increasing water turbidity regardless of the method used. Recoveries of seeded Giardia cysts exceeded those of Cryptosporidium oocysts in all types of water sampled. The sampling step in both methods resulted in the highest loss of seeded cysts and oocysts. Furthermore, much higher recovery efficiencies were obtained when the flotation step was avoided. The membrane filter method, using smaller tubes for flotation, was less time-consuming and cheaper. A serious disadvantage of this method was the lack of confirmation of presumptive cysts and oocysts, leaving the potential for false-positive Giardia and Cryptosporidium counts when cross-reacting algae are present in water samples.
Full Text
The Full Text of this article is available as a PDF (203.9 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Hansen J. S., Ongerth J. E. Effects of time and watershed characteristics on the concentration of Cryptosporidium oocysts in river water. Appl Environ Microbiol. 1991 Oct;57(10):2790–2795. doi: 10.1128/aem.57.10.2790-2795.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Heimer G. V., Taylor C. E. Improved mountant for immunofluorescence preparations. J Clin Pathol. 1974 Mar;27(3):254–256. doi: 10.1136/jcp.27.3.254. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LeChevallier M. W., Norton W. D., Lee R. G. Occurrence of Giardia and Cryptosporidium spp. in surface water supplies. Appl Environ Microbiol. 1991 Sep;57(9):2610–2616. doi: 10.1128/aem.57.9.2610-2616.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ongerth J. E., Stibbs H. H. Identification of Cryptosporidium oocysts in river water. Appl Environ Microbiol. 1987 Apr;53(4):672–676. doi: 10.1128/aem.53.4.672-676.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Riggs J. L., Dupuis K. W., Nakamura K., Spath D. P. Detection of Giardia lamblia by immunofluorescence. Appl Environ Microbiol. 1983 Feb;45(2):698–700. doi: 10.1128/aem.45.2.698-700.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sauch J. F. Use of immunofluorescence and phase-contrast microscopy for detection and identification of Giardia cysts in water samples. Appl Environ Microbiol. 1985 Dec;50(6):1434–1438. doi: 10.1128/aem.50.6.1434-1438.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]