RE: Cryptosporidia

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From:"Victor A. Tobias" <>
To:"Kellar, Eric" <kellarec@MSX.UPMC.EDU>
Date:Wed, 21 Jul 1999 08:09:37 -0700 (PDT)
Content-Type:TEXT/PLAIN; charset=US-ASCII

To all,

My brain was thinking of a different crypto when I suggessted a
mucicarmine. I agree with Eric that a giemsa is the best stain.


On Wed, 21 Jul 1999, Kellar, Eric wrote:

> Cryptosporidium parvum is an obligate intracellular parasite and has a
> monoxenous life cycle. The infective stage is a resistant oocyst, about
> 3.5-5 Ám in diameter, which can remain viable in water at 4C for over 6
> months.  Following ingestion and passage into the small intestine the oocyst
> ruptures to release 4 sporozoites. which immediately penetrate the apical
> epithelial cells or enterocytes of the intestinal villi. Once inside they
> undergo multiple fission, merogony (schizogony), to produce 8 Type I
> merozoites. The meronts eventually rupture releasing merozoites which
> reinfect other enterocytes. These type I meronts can cycle in the host
> indefinitely. After a number of generations, a second type of meront, type
> II, are formed. The trigger for this is not known. The type II meronts only
> have 4 merozoites. 
> These merozoites appear to form the gametes, upon penetrating into the
> enterocytes again. Some of the merozoites form a single female 
> macrogametocyte and others divide to form 16 motile, but non-flagellated,
> male microgametocytes. The microgametocytes rupture from the host cell and 
> locate and fuse with a macrogametocyte to form a zygote. This is the only
> diploid stage of the life cycle. Meiosis then follows, giving rise to 4 
> haploid sporozoites within the oocyst.. The oocyst breaks out of the cell
> and is passed out in the host feces. The prepatent period is generally about
> 4 
> days with patency lasting 6-10 days. The reproductive cycle can be very
> rapid, between 12-24 hrs leading to a rapid increase in the population
> In normal immunocompetent hosts, the infection is acute and self limiting.
> Surface proteins and glycoproteins are highly immunogenic and therefore
> leads to rapid elimination of the parasite.  In immunocompromised hosts the
> infection it is chronic and the numbers of parasites can soar resulting in
> the invasion of secondary sites such as the duodenum, large intestine,
> stomach, biliary and pancreatic ducts and respiratory tract and if untreated
> can result in death.
> The presence of the sporozoites results in changes in the host villi
> including, blunting of villi, crypt hyperplasia, cellular infiltration of
> the lamina propriaand the release of pro-inflammatory cytokines - IL6, IL8,
> and/or TNF-a and an increase in cellular permeability.
> Detection methods consist of finding oocysts in the stool or tissue with an
> H&E or occasionally after formalin fixation with a modified Ziehl-Neelsen
> method. I have had the best results with a Giemsa, PTAH and the
> Auramine-rhodamine fluorescent technique.
> Eric C. Kellar
> 	----------
> 	From:
> []
> 	Sent:  Tuesday, July 20, 1999 2:07 PM
> 	To:
> 	Subject:  Cryptosporidia
> 	Does anyone have a special stain to demonstrate cryptosporidia ?
> 	I have tried PAS, Grocott and Kinyoun's Acid Fast. The Parasitology
> Lab. got
> 	very good results on smears but it's difficult to stain them after
> routine
> 	processing.
> 	Any suggestions would be greatly appreciated !!
> 	Thanks.
> 	Marilyn Johnson
> 	Animal Health Labs.
> 	Edmonton, Alberta, Canada.

Victor Tobias
Manager Tissue Processing Lab
Washington Animal Disease Diagnostic Lab
Washington State University
Pullman Washington 99164-7034
(509) 335-5590
(509) 335-7424 fax

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