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ISOSPORA BELLI - Coggle Diagram
ISOSPORA BELLI
LAB DIAGNOSIS
. Oocysts can be observed in wet preparations, iodine stained preparations or acid-fast stained smears of concentrated stool specimens.
Isospora belli oocysts are acid fast and will also stain positive using the auramine o protocol commonly used to detect mycobacteria
. The sporont and sprobast fluoresce green when a fluorescent microscope is used to examine stool smears after auramine o staining.
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Oocysts can be observed in wet preparations, iodine stained preparations or acid-fast stained smears of concentrated stool specimens
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LIFE CYCLE
At time of excretion, the immature oocyst contains usually one sporoblast (more rarely two)The number 1. In further maturation after excretion, the sporoblast divides in two (the oocyst now contains two sporoblasts); the sporoblasts secrete a cyst wall, thus becoming sporocysts; and the sporocysts divide twice to produce four sporozoites each
The number 2. Infection occurs by ingestion of sporocysts-containing oocysts: the sporocysts excyst in the small intestine and release their sporozoites, which invade the epithelial cells and initiate schizogony
Trophozoites develop into schizonts which contain multiple merozoites. After a minimum of one week, the sexual stage begins with the development of male and female gametocytes
- Fertilization results in the development of oocysts that are excreted in the stoolThe number
The number 3. Upon rupture of the schizonts, the merozoites are released, invade new epithelial cells, and continue the cycle of asexual multiplication
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PATHOGENESIS
I. belli can cause marked villous atrophy, and crypt hyperplasia in the small intestine. Infection of the biliary tract by I. belli is also possible.
Inflammatory infiltrates in the lamina propria include eosinophils, neutrophils, lymphocytes and plasma cells.
The precise mechanism causing these changes is unknown, but they result in steatorrhea and malabsorption.
The parasite can complete it’s life cycle in the biliary tract and oocysts can be observed in bile (4). Stages are located in the bile duct epithelium (3).
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MORPHOLOGY
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The oocyst matures after excretion: the single sporoblast divides in two sporoblasts, which develop cyst walls, becoming sporocysts, which eventually contain four sporozoites each
When excreted, they are immature and contain one sporoblast
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