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Giardia tx info needed

ctfaulkn at utkvx.utk.edu ctfaulkn at utkvx.utk.edu
Mon Sep 5 03:01:26 EST 1994

In Article <34b7cv$hut at www.interramp.com>
knunan at .interramp.com writes:
>Can anyone tell me what the best treatment in terms of %erad-
>ication is for Giardia? And if the med side effects are worse
>than the infection or not.

The best treatment for eradication of Giardia is interruption of the
lifecycle by reducing fecal contamination of the environment.  This is 
a difficult proposition if you are talking about a kennel environment with
a number of infected hosts, especially if they are all in different stages
of the prepatent period (7 to 14 days).  A number of compounds have been
shown to be effective in killing the cysts in the environment (Zimmer et al
1988, Jour Amer Anim Hosp Assn 24: 379-385).  Roccal, used at the 
manufacturer's recommended concentration was effective at killing the cysts
with 1 minute of contact time at room temperature.  The efficacy of the
Quaternary Ammonium compounds is reduced in the presence of fecal matter, so
all feces should be removed from the floor prior to treatment.  Aqueous Iodine
is also effective, but it will stain the treated surface.  Iodine tablets are
also available for treatment of drinking water, but I believe the various
filtering devices on the market are more popular, and when used properly are
probably just as effective in preventing infection. 
It seems that most of the approved compounds for treating Giardiasis have been 
associated with side effects which vary in severity by individuals taking them.
I have no personal experience with Metronidazole, but friends who have taken 
it say "its worse than the infection".  Other compounds are reviewed in 
Barr and Bowman (1994, Compendium Contin Edu for the Pract Vet 16:603-609)
and Amer Med Assn (1993, Drug Evaluations pp 1649-1689).  Barr's paper is 
useful because the relative efficacy of each of the compounds is reviewed. 
In practice, Metronidazole (the drug of choice by the AMA) is less than 100%
efficacious. I have subjected my own pet to some rather rigorous regimens 
(25mg bid/ 5 days, and 14 days) without success.  Barr's recent work with 
Albendazole is promising (see above reference for citations of work in animals 
and humans).  The authors claim it is 50x more effective than Metronidazole, 
and 10 to 40x than Quinicrine hydrochloride. There were no side effects in
animals treated at 25mg bid/2 days. They note, however, that Albendazole is
suspected as being teratogenic and should not be given to pregnant animals. 
This drug has real promise for work in 3rd world countries where intestinal 
helminthiasis is often compounded by coinfections with Giardia.  The doses 
outlined should be effective against all of the parasites in a relatively 
short regimen, and the lack of side effects should result in a high degree of 
household compliance.  

Hope this is helpful.

*      Charles T. Faulkner       *
*  Univ of Tennessee, Knoxville  *
*   (ctfaulkn at utkvx.utk.edu)     *

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