will enable tracking of isolates during outbreak situa-tions.[15]

Little is known about the infection characteristics of different species and genotypes in humans and no clear clinical symptoms have been defined for any of the genotypes. New studies in humans and animal models are starting to shed light on the infection characteristics of the different C. parvum and C. hominis genotypes.[1'15]


The Cryptosporidium genome is ~ 10.4 Mb, contained in eight chromosomes ranging in size from 0.9 to 1.54 Mb. The C. parvum genome contains ~5000 genes, very few introns, less than 1% repeat sequences, and is 68% and 65% AT-rich, for genotypes 1 and 2, respectively.[3,15] Two genome projects, close to completion, are sequencing the genomes from two commonly used isolates of Cryp-tosporidium: strain H representing the human genotype 1 (C. hominis) and the Iowa strain representing the bovine genotype 2 (C. parvum). A new database, CryptoDB (, contains the genome data and public sequences and is a very useful tool for obtaining genomic data for Cryptosporidium.[16]

Gene Expression Analysis

There is currently no system for transfection of C. parvum for gene analysis. A recent study analyzed expression of the C. parvum Cpgp40/15 invasion glycoprotein through transfection of the tachyzoite stage of a related Apicom-plexan parasite, Toxoplasma gondii.[17] The first use of microarrays to analyze gene expression in epithelial cells infected with C. parvum demonstrated up-regulation and down-regulation of 236 genes out of a panel of 12,600. These included genes encoding heat-shock proteins, pro-inflammatory cytokines and chemokines, and structural genes, demonstrating considerable changes in host biochemical pathways.[18] In addition, a number of unknown genes were modulated, presenting new avenues of investigation.

MOLECULAR TESTING Clinical Diagnosis

The gold standard for diagnosis of C. parvum is detection of oocysts in clinical samples using microscopy and indirect immunofluorescence (IF). Several enzyme immu-noassay kits for detection of soluble stool antigens are available such as the Prospect T Cryptosporidium and Crypto CELISA. New and very rapid tests on the market are the ImmunoCard STAT! and ColorPAC solid-phase immunochromatographic immunoassays. Molecular techniques such as PCR are in development and provide a higher degree of sensitivity of detection than microscopy. One clinical trial demonstrated 83.7% sensitivity and 98.9% specificity using microscopy as compared to 100% sensitivity and specificity with PCR.[19] In another study,

Table 2 Molecular

assays for detection of C. parvum

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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