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diagnostic kits for Giardia

Charles T. Faulkner ctfaulkn at UTKUX1.UTK.EDU
Tue Nov 14 09:39:31 EST 1995

On Tue, 14 Nov 1995, colin semple wrote:

> Here is the abstract of a paper just in the final stages:
> During a seven month period 16,888 sodium acetate-acetic
> acid-formalin (SAF) fixed stool specimens were examined for
> the presence of parasites.  

	[stuff deleted]

> Contrary to some papers, this study suggests that in
> specimens with small numbers of Giardia cysts, commercially
> produced kits may not be any more sensitive than
> conventional microscopic examination of multiple specimens
> by experienced staff.
	Glad to see your work. Please keep me informed of your progress
as I would like to reference it when it becomes available. Your results 
are similar to some of the work we did in the early days of the ELISA 
development and marketing.  We found that while a positive result was not 
dependent on having cysts present in the stool, the relative sensitivity 
on a single exam was not much better than a single flotation exam.  We 
have recently completed a similar study w/ 2 of the ELISA tests in a 
canine population and hope to submit it for publication in the next year.

	Another question that is rarely addressed by advocates of the 
immunoassay approach concerns the predictive values of positive and 
negative test results.  When these tests are adopted for diagnostic use, 
practioneers need to keep in mind that the PPV is dependent on the 
prevalence of the parasite. Thus, it is important to differentiate between 
high risk...."skiers drinking from streams near Aspen" and low risk 
"other folks with GI signs and symptoms" patients prior to employing these
tests as diagnostic measures of the probability an individual is infected 
with Giardia/Cryptosporidium. I expect to see this problem get worse 
before it gets better given the future plans to couple these tests 
together for detction of Giardia/Crypto/E. histolytica, and increasing 
interest of hospital administrators to contain costs for diagnostic 
parasitologic examinations.  Just some wild and not so random thoughts.

*      Charles T. Faulkner       *   Get your facts first and then you
*  Univ of Tennessee, Knoxville  *   can distort them as much as you please.
*     (ctfaulkner at utk.edu)       *                Mark Twain

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