You are being redirected because this document is part of your ASTM Compass® subscription.
    This document is part of your ASTM Compass® subscription.


    A Comparison of Indirect Fluorescence, Modified Reference(Non-Acidified), and Modified Reference(Acidified) Techniques for Giardia Detection in Northeastern Waters

    Published: 0

      Format Pages Price  
    PDF (124K) 10 $25   ADD TO CART
    Complete Source PDF (9.4M) 597 $76   ADD TO CART


    Pennsylvania Gas & Water Company's Water Quality Laboratory has continuously monitored the company's watersheds since an outbreak of giardiasis in December, 1983. Twenty-five reservoirs are sampled monthly; approximately 3100 filters to date. Two techniques are employed; the reference method and an immunofluorescence technique (IFT). The reference method has been modified to obtain higher percent recoveries for routine monitoring. Samples were obtained from watersheds known to be positive and analyzed by IFT, Modified Reference (MR-N), and Modified Reference (MR-A, Final pH <2.0). Variations and drawbacks for each technique will be discussed, as well as statistical analyses. Thirtyone samples were analyzed and the greatest number of cysts were detected with IFT. The MR-A technique yielded the highest percentage of positive samples. Northeastern waters have excessive organic debris present which effects all three methods. However, the MR-A proved to be the method least affected by turbidity. Although recovery when monitoring the environment cannot be measured accurately, the MR-A seems to be the more efficient method for routine monitoring of Giardia cysts in northeastern waters.


    modified reference, immunofluorescence, turbidity, recovery, Giardia, cysts

    Author Information:

    McFarlane, SA
    Microbiologists, Pennsylvania Gas & Water Co., Scranton, Pa.

    Roberts, GB
    Microbiologists, Pennsylvania Gas & Water Co., Scranton, Pa.

    Committee/Subcommittee: D19.24

    DOI: 10.1520/STP17619S