Method 1623

Cryptosporidium and Giardia in Water by Filtration/IMS/FA

This method is for the collection and analysis of Cryptosporidium and Giardia in surface water and is also applicable for other types of water.  The sample is filtered and any oocytes, cysts, and extraneous materials are retained on the filter.  The filter is eluted and the eluate is centrifuged to pellet the oocysts and cysts, and the supernatant fluid is aspirated.  The oocysts and cysts are magnetized by attachment of magnetic beads conjugated to anti-Cryptosporidium and anti-Giardia antibodies. The magnetized oocysts and cysts are separated from the extraneous materials using a magnet, and the extraneous materials are discarded. The magnetic bead complex is then detached from the oocysts and cysts. The oocysts and cysts are stained on well slides with fluorescently labeled monoclonal antibodies and 4',6-diamidino-2-phenylindole (DAPI). The stained sample is examined using fluorescence and differential interference contrast (DIC) microscopy. 

Qualitative analysis is performed by scanning each slide well for objects that meet the size, shape, and fluorescence characteristics of Cryptosporidium oocysts or Giardia cysts. Quantitative analysis is performed by counting the total number of objects on the slide confirmed as oocysts or cysts.

Freezing samples, filters, eluates, concentrates, or slides may interfere with the detection and/or identification of oocysts and cysts. 
This method identifies the genera, Cryptosporidium or Giardia, but not the species. The method cannot determine the host species of origin, nor can it determine the viability or infectivity of detected oocysts and cysts.


(EPA: Office of Water)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   96 hours from sample collection (if shipped as a bulk sample) or filtration (if field filtered).
Preservatives:   Samples that were not collected the same day they were received, and that are received at >20°C or frozen, or samples that the laboratory has determined exceeded >20°C or froze during shipment, must be rejected.
Required Preps:   10L Cubitainer
Collection Method:   Grab sampling
Analytical Methodology:   Fluorescence and differential interference contrast (DIC) microscopy
Documentation:   1623

Analyte List*

Analyte Formula CAS Number Detection Limit

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.