vvEPA
United States
Environmental Protection
Agency
Office of Research
and Development
Cincinnati OH 45268
EPA815-K-99-62-
March 1999
CRITERIA FOR EVALUATION
OF PROPOSED PROTOZOAN
DETECTION METHODS
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CRITERIA FOR EVALUATION OF
PROPOSED PROTOZOAN DETECTION
METHODS
Alfred P. Dufour1
Maryann Feige2
H.D. Alan Lindquist1, Editor
Michael Messrier2
Stig RegH2
Crystal Rodgers2
Frank W. Schaefer1, III
Steven Schaub2
James Sinclair2
Larry J. Wymer1
'Office of Research and Development
2Office of Water
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CRITERIA FOR EVALUATION OF PROPOSED PROTOZOAN DETECTION
METHODS
Introduction:
Currently, the only EPA approved method for detection and quantitation of protozoan
cysts and oocysts in source and drinking water, is the "ICR Protozoan Method for Detecting
Giardia Cysts and Cryptosporidium Oocysts in Water by a Fluorescent Antibody Procedure (ICR
Microbial Laboratory Manual, Section VII, EPA/600/R-95/178, April 1996). Experience with
the ICR protozoan method has shown that it usually underestimates the levels and occurrence of
Giardia sp. and Cryptosporidium sp., the two protozoan parasites that it was designed to detect.
False positives and false negatives have been found during testing in a number of laboratories.
The ICR method has also been criticized for being complex and difficult to perform, yielding
highly variable results, demonstrating differential response in a variety of water matrices, and
being costly (Clancy, et al. 1997, Schaefer, 1997). To address these issues, alternate methods
have been proposed and preliminarily tested. Not all of the alternatives are complete methods.
Some are method components meant to substitute for the sampling, processing, staining or
detection steps used in the ICR method.
The result of the development of methods and method components has been a profusion
of procedures that have not been tested in a consistent manner. Many of these methods have not
been validated in a multi-laboratory, round robin format. A mechanism must be developed to
evaluate these proposed methods and method components. The recent development of draft EPA
method 1622 (SEP 98 DRAFT - Method 1622: Cryptosporidium in Water by Filtration/IMS/FA
(270 KB) -(EPA 821-R-98-010) may provide a useful guideline for evaluating proposed
methods. Method 1622 is a performance based method that includes multiple options for
sampling and processing that may be selected.
The problem in evaluating methods is that great variances exist in the testing of the
proposed methods. There are significant variations in the water matrices, the concentration of
protozoan cysts, or oocysts, and the method for enumeration of these protozoan spikes, the
quality of the spike material, and even the descriptions of the methods that have been provided
by developers. As a result, there is little comparability in the data that have been developed for
each proposed technique or method.
To evaluate the prospective utility of proposed methods and techniques it is necessary to
establish a logical paradigm for categorization and preliminary evaluation to determine if further
testing or investigation is warranted. Within the framework proposed, method replacements for
the ICR method may be expeditiously screened. This framework is designed to be robust enough
to allow comparison of widely divergent methods. This paradigm allows fair evaluation of a
number of prospective proposals, allowing those with a demonstrated likelihood of being better
than the ICR method to be tested further, while providing a set of necessary benchmarks for
method and technique developers to accomplish before consideration for further testing. This
framework will include a table that may be filled in by evaluators listing important characteristics
of proposed methods. Knowing this framework will allow method developers to focus their
energies on collecting the relevant data, and will guide them in the future research on method
improvements.
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The technical criteria for evaluation of performance of each method is based on testing in
a defined water matrix with defined oocyst populations, at a specified spiking rate, based on a
standardized method of spike enumeration. All of these criteria are reasonably obtainable.
Methods selected by this framework should be further tested under a yet to be developed
protocol using performance evaluation criteria, and a variety of water matrices. Description of
this type of testing is beyond the scope of this protocol.
Although C. parvum and G. lamblia are specifically addressed in the criteria for
evaluating methods proposed here, it should be possible to use these criteria to evaluate methods
proposed for detection of other protozoa. Adaptation of this method for other protozoa will have
to be thoughtful. Any adaptation to include further species should include species specific
parameters for preparation of seed for spiking experiments, and may require modification in
other criteria as well.
It is also not possible to include in any single document, or set of criteria, all of the
nuances of the application of those criteria. Evaluation of methods is ultimately an exercise in
decision making, which involves factors other than a strictly technical evaluation of the methods.
These criteria are intended only to help ensure that each method has an opportunity for a
scientifically sound evaluation of its respective technical merit.
Finally, these criteria are designed to evaluate entire methods. Individuals wishing to
have specific components of a method evaluated by the criteria outlined in this document must
include those components in the context of a complete method. Any method component,
however promising, does not exist independently of the entire method in which it is used. This
does not preclude re-assortment of method components at a future date to develop a better
method..
Technical criteria:
Statistical performance of method:
A variety of statistical measures are required to evaluate each method. These measures
must be reported on the basis of having run the entire method from sampling to the detection and
identification. In this way, the statistical measures will have validity and be useful for
comparison. Spiked sample sets must include blanks to determine if false positive results occur.
The only acceptable method for running spiked samples is to obtain a sufficient quantity
of reagent water for a typical application of the method, and to seed this quantity of water at a
variety of concentrations with cysts and oocysts from known sources maintained in defined
conditions. These must be counted by hemocytometer count (EPA 821-R-98-010, September
1998), or by another method demonstrated to give results of equal or greater precision and
accuracy to hemocytometer counting.
All parameters in the statistical performance of the method must be based on at least 10
spiked samples and one blank sample prepared in reagent grade water being run through the
entire method. Spike material must be obtained from a documented source of laboratory animal
derived cysts and oocysts, purified by at least three levels of purification with the final method
being cesium chloride purification (Arrowood and Donaldson, 1996) or equivalent. Cysts of G.
lamblia should be 2 weeks old or less and should have at least 90% phase bright (highly
birefringent) organisms, and oocysts of C. parvum must be less than three months old and have
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at least 80% phase bright organisms. The cysts and oocysts should not be preserved, but should
be stored in a medium for decontamination, for example water containing antibiotics. Care
should be taken to avoid influencing the viability or infectivity of test organisms during
purification and storage.
Spike material must be counted using a bright line hemocytometer using appropriate
technique (EPA 821-R-98-010, September 1998). A suitable aliquot is then added to the sample
of reagent grade water. Reagent grade water has a resistivity of 18 megaohms or greater, and is
substantially free from bacterial contamination by filtration through a 0.2 micron pore sized
filter. Sterility of this water must be checked at regular intervals by culture. The final spike dose
is to be 10 cysts and oocysts per liter, and the minimum sample volume should be 10 liters,
although larger volumes may be tested if the method design is intended for use with larger
volume applications. Spiked water samples must be used within 12 hours of enumeration of the
spike material. After spiking a carboy with a seed of organisms, an inoculum of equal volume to
the volume of oocyst stock spiked into the water sample must be enumerated by a method other
than the initial method of counting. This may include staining the oocysts in this inoculum and
counting stained cysts and oocysts, or some other method of enumeration. This is to ensure the
accuracy of the spike dose.
The hemocytometer counts must be recorded in a signed and dated laboratory notebook,
available for inspection at the time a method is presented. Failure to present this data shall result
in a score of 0 for all statistical parameters. In addition, for every 10 samples run through the
complete method, at least one blank must be run. Blanks may be used for statistical significance
only if at least ten blanks are run. Although blanks may be run at a higher rate than one in
eleven, care must be taken to intersperse blanks and positive samples to attempt to blind the
analysis. All samples and the blank should be prepared by an investigator other than the
individual analyzing the data, in an attempt to operate the test in a blind fashion. In the event
that the spike for any sample is prepared by an individual who is the analyst for that sample, the
fact that the test was not run in a blind fashion must be reported.
This procedure is not designed for the specific testing of method components. If method
components are to be tested, they should be included in a complete method. An example of this
would be to include a new processing step into Method 1622, using one of the recommended
filtration devices, the new method component for processing, and one of the Method 1622
analysis protocols.
Specific Criteria
A set of criteria defining significant technical parameters and characteristics to be used as
evaluation measures for proposed methods was developed to determine if further testing of
proposed methods should be undertaken. These parameters were separated into criteria with
each criterion being assigned a number of response levels designed to be inclusive of the possible
set of responses. It is understood that it may not be possible to account for every contingency
when designing a comprehensive set of responses to a variable, and that good scientific
judgement should be used when assigning appropriate scores to methods that fall outside the
parameters of the response set for any criterion.
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Requirements for Data Generation to Measure the Statistical Performance
A variety of statistical measures are required to evaluate each method. They must be
reported on the basis of having conducted the entire method from sampling to detection and
identification to have validity or usefulness for comparison. All parameters in the statistical
performance of the method must be based on at least 10 spiked samples and one blank sample
prepared in accordance with the following guidelines.
All spiked samples and blanks are to be prepared using reagent grade water with a
resistivity of 18 milliohms or greater, and is substantially free from bacterial contamination by
filtration through a 0.2 micron pore sized filter. Sterility of this water must be checked at regular
intervals by culture. The sole exception to the use of distilled water is the case wherein the
absence of particulates is an interference to the correct operation of the proposed method In this
case, chemically defined particulate may be added at a defined rate to allow the method to work.
Spike material must be obtained from a traceable source of laboratory animal derived
cysts and oocysts. A traceable source of oocysts should be reasonably available to all qualified
researchers, should maintain documentation of the species of animal from which the parasites
were initially isolated, the species of laboratory animals within which the parasites have been
passed, and the methods used in propagation of the parasite. Parasite spike material should be
purified to a nearly homogeneous population of monodispersed parasites with final processing
method of cesium chloride purification (Arrowood, and Donaldson, 1996) or equivalent Cysts of
d°^ TSt bC l6SS than 3 W6eks °ld ^ °6cysts ofC Parvum must be le*s than six months
old. While these organisms should not be preserved, they should be stored in a medium designed
to retard the growth of bacteria, for example, reagent grade water containing antibiotics.
All protozoan cysts or oocysts must be enumerated by hemocytometer count or by
another method demonstrated to give results of equal or greater precision and accuracy than
hemocytometer counting. Enumeration by hemocytometer refers to material being counted using
a bright line hemocytometer designed for phase optics. After the hemocytometer chamber is
filled with an appropriate volume and the hemocytometer placed on the microscope stage it must
be allowed to settle for 2 minutes, then protozoa are counted using phase contrast optics at no
less than 200 x total magnification. Estimates are made by counting the four, 1 mm2 comers of
the hemocytometer grid etched into the platform. Cysts or oocysts touching either the top or
bottom, and either the right or left line are included, those touching the opposite line are
excluded. At least 50, and not more than 120, cysts and oocysts must be counted per
hemocytometer platform. If cysts and oocysts are not monodispersed, then the cyst or oocyst
preparation must be treated to provide for monodispersion (i.e. by addition of 0.01% (v/v) Tween
20 and vortexing for 2 minutes) and recounted. The average of 6 hemocytometer platforms
counted in this way is taken and used to calculate the dilution required to prepare a concentration
of 10 cysts and/or oocysts per 1 liter. A suitable portion is then added to the sample of reagent
grade water. The final spike dose is calculated to be 10 cysts and/or oocysts per liter, and the
minimum sample volume should be 10 liters, although larger volumes may be tested'if the
method design is intended for use with larger volume applications. Spiked water samples must
be used within 12 hours of enumeration of the spike material.
Well documented raw data should be available for inspection at the time a method is
presented. If this type of data is not available, the evaluation of statistical parameters will not be
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possible.
In addition, for every 10 samples analyzed by the complete method, at least one blank
must be included. Blanks may be used for statistical significance only if at least ten blanks are
used. Care must be taken to intersperse blanks and positive samples. If possible, all samples and
the blank should be prepared by an investigator other than the individual analyzing the data in an
attempt to operate the test in a blind fashion. In the event that the spike for any sample is
prepared by an individual who is the analyst for that sample, the fact that the test was not
conducted in a blind fashion must be reported.
This procedure is not designed for the specific testing of method components If method
components are to be tested, they should be included in a complete method. An example of this
would be to include a new processing step into Method 1622, using one of the recommended
filtration devices, the new method component for processing, and one of the Method 1622
analysis protocols.
Scoring Criteria
Statistical Performance of Method
All of the technical parameters must be adhered to in testing to develop statistical
parameters. Failure to adhere to these guidelines will result in a score of 0 for all technical
statistical parameters.
Percent recovery:
The percent recovery is the percent of the initial spike dose recovered at the end of a method
trial In order for percent recovery to be valid, it must be noted as a method percent recovery in
which the spike was added to a water sample, and the entire method performed, from initial
concentration to final sample enumeration. A spiked sample that is used to test the efficacy of a
method component may provide a component percent recovery, but not a method percent
recovery.
Percent recovery:
Not reported or 0%
<25%:
25-<50%
50-<75%
75- 100%
Rank
0
Limit of detection:
The number of cysts and oocysts that may be reliably detected per unit volume reported as #
cysts and oocysts per liter by species is the limit of detection.
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Limit of Detection:
Rank
Not reported or >10,000/1
10,000->1,000:
1,000- >100
100- >10
Precision:
Precision relates to repeatability, and is the percent coefficient of variation (standard deviation as
a percent of mean) for the method when performed in its entirety using spiked samples.
Precision:
Rank
Not reported, or > 100%
0
<100-75%
<75- 50%
<50- 25%
<25%
Lower 95% confidence limit:
This confidence limit represents the minimum number of cysts or oScysts that will be detected in
95 of 100 trials if the method were to be performed using the conditions specified in this
document. The limit is calculated from the sample mean using the central limit theorem and is a
single tailed test derived from the percent recovery data. An example calculation of this would
be: the average recovery - [1.645 • (the standard deviation of the recovery/the square root of the
sample size)].
Lower 95% confidence limit
Rank
Not reported, or <0
> 0-25
>25- 50
>50 - 75
>75
0
4
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Specificity:
Specificity is the true negative rate. True negatives can only be determined by using a
confirmatory test. All of the cysts and oocysts in an inoculated sample of reagent grade water
should in fact be cysts and oocysts. Therefore specificity should be a measure of the ability to
confirm the identity of cysts or oocysts. For example, in the ICR method, it may not be possible
to confirm by,differential interference contrast (DIG) all objects that react with the fluorescent
antibody and are therefore only presumed positive. This presumptive nature may confound
analysis of the results of the method. It is the nature of certain test types that confirmation may
be easier or more difficult. This difference may change or be magnified as the matrix becomes
more complex. Many proposed methods will not have addressed the matrix effect or ability to
confirm presumptive objects. When only known positive material is added, the specificity is the
ratio of confirmed to presumptive objects as a percent.
Specificity:
Rank
Not feported, or 0%
0
<25%
25- <50%
50- <75%
75- 100%
False positive rate:
The false positive rate is the apparent detection of cysts and oocysts in known blank samples.
Since, in some samples, less than 100 percent of the sample volume may routinely be analyzed,
this is generally a presence/absence criterion. This is reported as the number of positives
detected in blank trials randomly interspersed with positive trials.
False positive rate:
Not reported, or blank samples not performed, or false positives ;> 20%
False positives present but fewer than 10 blank samples were analyzed
No false positives present, but fewer than 10 blank samples analyzed
More than 10 blanks analyzed, and percent of false positives >5%, and <20%
More than 10 blanks analyzed and percent of false positives < 5%
Rank
0
1
2
3
4
Collaborative testing:
Collaborative multi-laboratory testing is exemplified by the ASTM format (D 2777-96, 1996).
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If possible all statistical measures should be derived from collaborative testing. In the earliest
stages of testing, there should be at least confirmation of methods and results by one or more
independent laboratories. If no independent laboratory testing has been carried out the score for
this category would be zero, however, independent laboratory testing to achieve a 1 or 2 score
need not be in the above described multi-laboratory collaborative format.
Collaborative testing
Rank
No independent laboratory testing undertaken
Independent laboratory confirmation underway
Independent laboratory confirmation undertaken successfully
Collaborative multi-laboratory (ASTM-like) testing begun, not yet finished
Collaborative, multi-laboratory testing completed
Nature of Data Generated:
This is a description of the data provided by the method. It must include the following-
Organism:
This is a taxonomic description of that which is detected by the method. The taxonomic level to
which a target organism is reliably identified and the method of this determination should be
described. Taxonomic status of Giardia sp. cysts and Cryptosporidium sp. oocysts may be
confirmed by examination under DIG microscopy. The use of 4,6-diamidino2-phenyl-indole
dihydrochlonde (DAPI) staining in Method 1622 is also intended as a confirmatory technique
All antibody based methods reported to date have shown some level of cross reactivity with other
species. Because of the difficulty of confirming protozoan presumptive identification and the
lack of specificity of antibody based methods, any proposed complete method must include some
mechanism of confirmation of taxonomic status, beyond antibody recognition Modern
molecular methods offer the possibility of highly specific identification techniques. In the case
of methods incorporating these techniques, it is necessary to ensure that the identification
encompasses all isolates of a species that are infective to humans. Any new, proposed method of
taxonomic confirmation other than enhanced contrast microscopy should be validated against
DIG microscopy in a multi-laboratory study.
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Organism:
The method to identify an organism to genus is not confirmed by multi-laboratory
study, or it does not include a method to confirm the identification of the organism
or the method does not detect all strains of the target species known to be infective
to humans
Identification to genus of the organism(s) is by non-selective methods
Organisms of interest are identified to genus with a selective test (that selectively
identifies target organisms of interest from background particles), and an
independent confirmatory test
Two independent testing mechanisms, at least one is valid to species level
identification, and at least one is a selective test
Organisms of interest identified, and confirmed by an independent test as a strainfs)
significant to human health
Rank
0
1
2
Viability:
Viability should always be described in terms of evolutionary significance. In this sense a
viable organism has the ability to pass genetic material on to the next generation A '
demonstration of the ability to excyst represents excystation ability. The ability to infect a cell is
fJe!rr? , ^^ A tCSt ^ demonstrates ** « organism hasfce ability to
infect and cause clinical disease has shown clinical infectivity. A test demonstrating the
r.tThTrf , arger nrber °f ViaWe CyStS °r °6cyStS than was Present in the inactive dose, or
a test that directly correlates with this is a viability test. The reference method for demonstrating
viability is parasite proliferation via infecting susceptible animals resulting in cyst or oocy "
havt nSrat cr tf ' * ^ * **"** Pr°liferation> or det-tion of infective forms that
have proliferated m the appropriate tissue on necropsy. Surrogate viability indicators are tests
hat have been tested alongside the reference method and have been found to be correlated wih
the reference method. Most surrogate viability indicators, may be found to deviate from this
correlation under certain specific conditions. If the method is not designed to give viability
information, then this column should be left blank.
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Viability:
Rank
Viability data indicated by a surrogate viability indicator that has not been validated
against the reference standard (animal infectivity model)
Surrogate viability indicator tested against one defined set of conditions and poorly
correlated to reference standard, or found to be poorly correlated to the reference
standard under conditions expected in the type of sample analyzed
Surrogate viability indicator data validated against reference standard, under one
defined set of conditions
Surrogate viability indicator data validated against reference standard using
numerous conditions, correlating well with the reference standard in several of these
conditions
Surrogate viability indicator data validated against reference standard, high
correlation between the test and animal infectivity found in all of a broad range of
conditions tested, or method includes the reference test
Method Description
The description of the method must be thorough enough to allow evaluation of the completeness
availability and practicality of the method.
General description:
The general description should be sufficient to allow a scientist or technician, unfamiliar with the
method, but with relevant experience to perform the method and achieve results comparable to
those reported by the developers. The format used is to be determined by the method developer
but should include: scope and application, summary of method, definitions, interferences safety
equipment and supplies, reagents and standards, sample collection, preservation and storage '
quality control, calibration and standardization procedure, data analysis and calculations me'thod
performance, pollution prevention, waste management, references, tables, diagrams flowcharts
and validation data. The description should serve as a complete, self contained instruction set for
evaluating a source or drinking water sample, from sampling through analysis, interpretation and
reporting of results. Failure to include any of these steps will result in a finding that the method
description is incomplete.
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General description:
Rank
Incomplete, not given
0
Well described but not complete
Apparently complete enough to allow independent testing
Complete, tested by one independent laboratory
Complete, tested by independent laboratories, and it is written in a format recognized
by the U.S. Environmental Protection Agency, or by an international consensus
methods validation organization (such as the American Society for Testing and
Materials or AOAC International)
3
4
Sampling:
The section on sampling must include information as to the range of sample volumes within
which the method will perform as described including sample holding times and preservation
techniques, ability to filter sample at sampling location, or at the laboratory. Other special
limitations on sampling should be described here.
Sampling:
Not described, or described in general terms, or described with no test data
presented, or well described but would not allow testing in suitable range of water
types/volumes for practical use
Not completely described, some test data presented, full
range of parameters unknown
Well described would allow water testing in an acceptable range of conditions
Tested by multiple laboratories, demonstrated to be effective with either source or
drinking water
Tested in a collaborative multi-laboratory study demonstrating that sampling of both
source and drinking water yields similar statistical recovery results
Rank
1
2
3
4
Managerial Criteria:
This element is intended to encompass the range of managerial concerns that may arise during
the implementation of methods, either in a collaborative multi-laboratory effort, or during actual
implementation of a method. These managerial considerations should be addressed within the
methods description, however, since these considerations may exceed the requirements of the
methods description format chosen by the developer, they may be included in a separate
document. This information is to include a full description of: personnel required for method
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performance including skill levels as well as training requirements for the personnel performing
the method broken down by technique where appropriate, a list of equipment and supply
providers and whether these providers meet industry quality assurance standards, and the open
market availability for any critical or proprietary components.
Managerial Criteria:
Rank
If none of this information is given or it is not documented
0
If this information is partially complete, or any supporting documentation is only
partially available
If all points are addressed, but some of the information is given in non-quantitative
fashion, or .includes general or anecdotal evidence
If all points are covered, but there is no evidence of independent confirmation of the
information of some of the information
If all points are thoroughly addressed, and supported by independent confirmation,
and all critical method components are readily available on the open market
Likely candidates for future research:
Certain methods or method components may not be available for immediate use, but might be
likely candidates for future use. These may include methods wherein the current
equipment/supply sources are limited in some way, but may become available in the future or
methods providing particular promise but still lacking critical elements that would allow a '
decision for further evaluation to be made. These candidates should be denoted by a non-
numenc symbol. This denotation indicates that the method is unsuitable for use as an alternative
to existing method/methods at this time.
A value of 0 in any of the reporting categories except viability would result in the method
being sent to its originator for further information, revision, or further testing. All methods that
have scored in each category are then compared for numerical score. The numerical score should
have relevance to both the suitability of the method for use and for the state of preparedness of
the method at the time of scoring. The higher the numerical score, the better the likelihood that
the method is prepared to a sufficient state of readiness to be tested against the current reference
method.
It may also be desirable to include a narrative section with a method rating, that addresses
such issues as: market availability, comparative assessments with existing methods, overall cost,
adaptability of the test for other organisms, etcetera, that were not addressed directly in the
numerical ranking. A narrative section would provide an opportunity to specifically state any
exceptional features of a proposed method, either positive or negative. Care should be taken to
address both positive and negative aspects of each test being evaluated in any attached narrative
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Literature Cited:
61 FR 24354 (Information Collection Rule) - National Primary Drinking Water Regulations-
Monitoring Requirements for Public Drinking Water Supplies; Final Rule.
Arrowood, M.J., and Donaldson, K. 1996. Improved purification methods for calf-derived
Cryptosporidium parvum oocysts using discontinuous sucrose and cesium chloride
gradients. J. Eukaryot Microbiol 43(5) p89S.
Clancy, JL., Hargy, T.M., and Schaub, S. 1997. Improved Sampling Methods for the Recovery
ofGmrdia and Cryptosporidium from Source and Treated Water. In: 1997 International
Symposium on Waterborne Cryptosporidium proceedings, March 2-5 1997 Newport
Beach California. Fricker, C.R., J.L. Clancy, and P.A. Rochelle, Eds. American Water
Works, Denver CO. pp: 79-86.
D 2777;*6' 1996' Standard Practice for Determination of Precision and Bias of Applicable Test
Methods of Committee D-19 on Water. Annual Book of ASTM Standards Vol 11 01
ASTM West Conshohocken, PA. ' ' '
EPA 821-R-98-010 September 1998 DRAFT, Method 1622: Cryptosporidium in water by
Filtration/IMS/FA. United States Environmental Protection Agency, Office of Water
Washington, DC 20460.
Fout, G., Schaefer, III, F.W., Messer, J.W., Dahling,D.R., and Stetler, R.E. April 1996 ICR
Microbial Laboratory Manual. EPA/600/R-95/178. United States Environmental
Protection Agency, Office of Research and Development, Washington, DC 20460.
Schaefer,III, F.W. 1997. Detection of Protozoan Parasites in Source and Finished Drinking
Waters. In: Manual of Environmental Microbiology. Hurst, C.J., G.R Knudsen MJ
Mclnerney, L.D. Stetzenbach, and M.V. Walter. Eds. ASM Press. Washington D C pp
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Appendix A
Table to filled in by evaluators, containing evaluation results for the method identifiers 1-4 as
referenced in the text.
I
D
%
R
D
L
P
R
C
L
S
P
F
P
L
T
DATA
O
R
^=
V
I
•g*"' —
MDSC
G
D
S
M
I
N
E
S
M
C
F
U
T
Max
C
0
M
56
Method identifier: M ID
Statistical performance: SPER
Percent recovery: %R
Limit of detection: DL
Precision: PR
Lower 95% Confidence Limit:
CL
Specificity: SP
False positive rate: FP
Collaborative testing: CT
Nature of data generated: DATA
Organism: OR
Viability: VI
Method description: MDSC
General description: GD
Sampling: SM
Interferences: IN
Equipment and supplies: ES
Managerial criteria: MC
Likely candidates for future: FUT
Comments: COM
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